This list is used to save changes on the servers state. So when serveral threads
are used, it must be locked. The changes are then applied in the sync-point. To
do so, servers_update_status has be moved in the sync-point. So this is useless
to lock it at this step because the sync-point is a protected area by iteself.
For now, we have a list of each type per thread. So there is no need to lock
them. This is the easiest solution for now, but not the best one because there
is no sharing between threads. An idle connection on a thread will not be able
be used by a stream on another thread. So it could be a good idea to rework this
patch later.
This is a huge patch with many changes, all about the DNS. Initially, the idea
was to update the DNS part to ease the threads support integration. But quickly,
I started to refactor some parts. And after several iterations, it was
impossible for me to commit the different parts atomically. So, instead of
adding tens of patches, often reworking the same parts, it was easier to merge
all my changes in a uniq patch. Here are all changes made on the DNS.
First, the DNS initialization has been refactored. The DNS configuration parsing
remains untouched, in cfgparse.c. But all checks have been moved in a post-check
callback. In the function dns_finalize_config, for each resolvers, the
nameservers configuration is tested and the task used to manage DNS resolutions
is created. The links between the backend's servers and the resolvers are also
created at this step. Here no connection are kept alive. So there is no needs
anymore to reopen them after HAProxy fork. Connections used to send DNS queries
will be opened on demand.
Then, the way DNS requesters are linked to a DNS resolution has been
reworked. The resolution used by a requester is now referenced into the
dns_requester structure and the resolution pointers in server and dns_srvrq
structures have been removed. wait and curr list of requesters, for a DNS
resolution, have been replaced by a uniq list. And Finally, the way a requester
is removed from a DNS resolution has been simplified. Now everything is done in
dns_unlink_resolution.
srv_set_fqdn function has been simplified. Now, there is only 1 way to set the
server's FQDN, independently it is done by the CLI or when a SRV record is
resolved.
The static DNS resolutions pool has been replaced by a dynamoc pool. The part
has been modified by Baptiste Assmann.
The way the DNS resolutions are triggered by the task or by a health-check has
been totally refactored. Now, all timeouts are respected. Especially
hold.valid. The default frequency to wake up a resolvers is now configurable
using "timeout resolve" parameter.
Now, as documented, as long as invalid repsonses are received, we really wait
all name servers responses before retrying.
As far as possible, resources allocated during DNS configuration parsing are
releases when HAProxy is shutdown.
Beside all these changes, the code has been cleaned to ease code review and the
doc has been updated.
Don't forget to allocate tmptrash before using it, and free it once we're
done.
[wt: introduced by commit 64cc49cf ("MAJOR: servers: propagate server
status changes asynchronously"), no backport needed]
Fix regression introduced by commit:
'MAJOR: servers: propagate server status changes asynchronously.'
The building of the log line was re-worked to be done at the
postponed point without lack of data.
[wt: this only affects 1.8-dev, no backport needed]
For HTTP/2 we'll need some buffer-only equivalent functions to some of
the ones applying to channels and still squatting the bi_* / bo_*
namespace. Since these names have kept being misleading for quite some
time now and are really getting annoying, it's time to rename them. This
commit will use "ci/co" as the prefix (for "channel in", "channel out")
instead of "bi/bo". The following ones were renamed :
bi_getblk_nc, bi_getline_nc, bi_putblk, bi_putchr,
bo_getblk, bo_getblk_nc, bo_getline, bo_getline_nc, bo_inject,
bi_putchk, bi_putstr, bo_getchr, bo_skip, bi_swpbuf
In order to prepare multi-thread development, code was re-worked
to propagate changes asynchronoulsy.
Servers with pending status changes are registered in a list
and this one is processed and emptied only once 'run poll' loop.
Operational status changes are performed before administrative
status changes.
In a case of multiple operational status change or admin status
change in the same 'run poll' loop iteration, those changes are
merged to reach only the targeted status.
Leaving the maintenance state and if the server remains in stopping mode due
to a tracked one:
- We mistakenly try to grab some pending conns and shutdown backup sessions.
- The proxy down time and last change were also mistakenly updated
snr_resolution_cb can be called with <nameserver> parameter set to NULL. So we
must check it before using it. This is done most of time, except when we deal
with invalid DNS response.
This reverts commit 19e8aa58f7.
It causes some trouble reported by Manu :
listen tls
[...]
server bla 127.0.0.1:8080
[ALERT] 248/130258 (21960) : parsing [/etc/haproxy/test.cfg:53] : 'server bla' : no method found to resolve address '(null)'
[ALERT] 248/130258 (21960) : Failed to initialize server(s) addr.
According to Nenad :
"It's not a good way to fix the issue we were experiencing
before. It will need a bigger rewrite, because the logic in
srv_iterate_initaddr needs to be changed."
Historically the DNS was the only way of updating the server IP dynamically
and the init-addr processing and state file load required the server to have
an FQDN defined. Given that we can now update the IP through the socket as
well and also can have different init-addr values (like IP and 'none') - this
requirement needs to be removed.
This patch should be backported to 1.7.
The server state and weight was reworked to handle
"pending" values updated by checks/CLI/LUA/agent.
These values are commited to be propagated to the
LB stack.
In further dev related to multi-thread, the commit
will be handled into a sync point.
Pending values are named using the prefix 'next_'
Current values used by the LB stack are named 'cur_'
This patch fixes a bug where some servers managed by SRV record query
types never ever recover from a "no resolution" status.
The problem is due to a wrong function called when breaking the
server/resolution (A/AAAA) relationship: this is performed when a server's SRV
record disappear from the SRV response.
The function srv_set_fqdn() is used to update a server's fqdn and set
accordingly its DNS resolution.
Current implementation prevents a server whose update is triggered by a
SRV record from being linked to an existing resolution in the cache (if
applicable).
This patch aims at fixing this.
Make it so for each server, instead of specifying a hostname, one can use
a SRV label.
When doing so, haproxy will first resolve the SRV label, then use the
resulting hostnames, as well as port and weight (priority is ignored right
now), to each server using the SRV label.
It is resolved periodically, and any server disappearing from the SRV records
will be removed, and any server appearing will be added, assuming there're
free servers in haproxy.
As DNS servers may not return all IPs in one answer, we want to cache the
previous entries. Those entries are removed when considered obsolete, which
happens when the IP hasn't been returned by the DNS server for a time
defined in the "hold obsolete" parameter of the resolver section. The default
is 30s.
This patch is a major upgrade of the internal run-time DNS resolver in
HAProxy and it brings the following 2 main changes:
1. DNS resolution task
Up to now, DNS resolution was triggered by the health check task.
From now, DNS resolution task is autonomous. It is started by HAProxy
right after the scheduler is available and it is woken either when a
network IO occurs for one of its nameserver or when a timeout is
matched.
From now, this means we can enable DNS resolution for a server without
enabling health checking.
2. Introduction of a dns_requester structure
Up to now, DNS resolution was purposely made for resolving server
hostnames.
The idea, is to ensure that any HAProxy internal object should be able
to trigger a DNS resolution. For this purpose, 2 things has to be done:
- clean up the DNS code from the server structure (this was already
quite clean actually) and clean up the server's callbacks from
manipulating too much DNS resolution
- create an agnostic structure which allows linking a DNS resolution
and a requester of any type (using obj_type enum)
3. Manage requesters through queues
Up to now, there was an uniq relationship between a resolution and it's
owner (aka the requester now). It's a shame, because in some cases,
multiple objects may share the same hostname and may benefit from a
resolution being performed by a third party.
This patch introduces the notion of queues, which are basically lists of
either currently running resolution or waiting ones.
The resolutions are now available as a pool, which belongs to the resolvers.
The pool has has a default size of 64 resolutions per resolvers and is
allocated at configuration parsing.
Introduction of a DNS response LRU cache in HAProxy.
When a positive response is received from a DNS server, HAProxy stores
it in the struct resolution and then also populates a LRU cache with the
response.
For now, the key in the cache is a XXHASH64 of the hostname in the
domain name format concatened to the query type in string format.
Prior this patch, the DNS responses were stored in a pre-allocated
memory area (allocated at HAProxy's startup).
The problem is that this memory is erased for each new DNS responses
received and processed.
This patch removes the global memory allocation (which was not thread
safe by the way) and introduces a storage of the dns response in the
struct
resolution.
The memory in the struct resolution is also reserved at start up and is
thread safe, since each resolution structure will have its own memory
area.
For now, we simply store the response and use it atomically per
response per server.
In the process of breaking links between dns_* functions and other
structures (mainly server and a bit of resolution), the function
dns_get_ip_from_response needs to be reworked: it now can call
"callback" functions based on resolution's owner type to allow modifying
the way the response is processed.
For now, main purpose of the callback function is to check that an IP
address is not already affected to an element of the same type.
For now, only server type has a callback.
This patch introduces a some re-organisation around the DNS code in
HAProxy.
1. make the dns_* functions less dependent on 'struct server' and 'struct resolution'.
With this in mind, the following changes were performed:
- 'struct dns_options' has been removed from 'struct resolution' (well,
we might need it back at some point later, we'll see)
==> we'll use the 'struct dns_options' from the owner of the resolution
- dns_get_ip_from_response(): takes a 'struct dns_options' instead of
'struct resolution'
==> so the caller can pass its own dns options to get the most
appropriate IP from the response
- dns_process_resolve(): struct dns_option is deduced from new
resolution->requester_type parameter
2. add hostname_dn and hostname_dn_len into struct server
In order to avoid recomputing a server's hostname into its domain name
format (and use a trash buffer to store the result), it is safer to
compute it once at configuration parsing and to store it into the struct
server.
In the mean time, the struct resolution linked to the server doesn't
need anymore to store the hostname in domain name format. A simple
pointer to the server one will make the trick.
The function srv_alloc_dns_resolution() properly manages everything for
us: memory allocation, pointer updates, etc...
3. move resolvers pointer into struct server
This patch makes the pointer to struct dns_resolvers from struct
dns_resolution obsolete.
Purpose is to make the resolution as "neutral" as possible and since the
requester is already linked to the resolvers, then we don't need this
information anymore in the resolution itself.
A couple of new functions to allocate and free memory for a DNS
resolution structure. Main purpose is to to make the code related to DNS
more consistent.
They allocate or free memory for the structure itself. Later, if needed,
they should also allocate / free the buffers, etc, used by this structure.
They don't set/unset any parameters, this is the role of the caller.
This patch also implement calls to these function eveywhere it is
required.
This patch adds a new stats socket command to modify server
FQDNs at run time.
Its syntax:
set server <backend>/<server> fqdn <FQDN>
This patch also adds FQDNs to server state file at the end
of each line for backward compatibility ("-" if not present).
This patch adds server_template_init() function used to initialize servers
from server templates. It is called just after having parsed a 'server-template'
line.
This patch makes backend sections support 'server-template' new keyword.
Such 'server-template' objects are parsed similarly to a 'server' object
by parse_server() function, but its first arguments are as follows:
server-template <ID prefix> <nb | range> <ip | fqdn>:<port> ...
The remaining arguments are the same as for 'server' lines.
With such server template declarations, servers may be allocated with IDs
built from <ID prefix> and <nb | range> arguments.
For instance declaring:
server-template foo 1-5 google.com:80 ...
or
server-template foo 5 google.com:80 ...
would be equivalent to declare:
server foo1 google.com:80 ...
server foo2 google.com:80 ...
server foo3 google.com:80 ...
server foo4 google.com:80 ...
server foo5 google.com:80 ...
This patch moves the code which is responsible of finalizing server initializations
after having fully parsed a 'server' line (health-check, agent check and SNI expression
initializations) from parse_server() to new functions.
This patch moves the code responsible of copying default server settings
to a new server instance from parse_server() function to new defsrv_*_cpy()
functions which may be used both during server lines parsing and during server
templates initializations to come.
These defsrv_*_cpy() do not make any reference to anything else than default
server settings.
'resolvers' setting was not duplicated from default server setting to
new server instances when parsing 'server' lines.
This fix is simple: strdup() default resolvers <id> string argument after
having allocated a new server when parsing 'server' lines.
This patch must be backported to 1.7 and 1.6.
In server_parse_sni_expr(), we use the "proxy" global variable, when we
should probably be using "px" given as an argument.
It happens to work by accident right now, but may not in the future.
[wt: better backport it]
Any valid keyword could not be parsed anymore if provided after 'source' keyword.
This was due to the fact that 'source' number of arguments is variable.
So, as its parser srv_parse_source() is the only one who may know how many arguments
was provided after 'source' keyword, it updates 'cur_arg' variable (the index
in the line of the current arg to be parsed), this is a good thing.
This variable is also incremented by one (to skip the 'source' keyword).
This patch disable this behavior.
Should have come with dba9707 commit.
'usesrc' setting is not permitted on 'server' lines if not provided after
'source' setting. This is now also the case on 'default-server' lines.
Without this patch parse_server() parser displayed that 'usersrc' is
an unknown keyword.
Should have come with dba9707 commit.
This reverts commit 266b1a8 ("MEDIUM: server: Inherit CLI weight changes and
agent-check weight responses") from Michal Idzikowski, which is still broken.
It stops propagating weights at the first error encountered, leaving servers
in a random state depending on what LB algorithms are used on other servers
tracking the one experiencing the weight change. It's unsure what the best
way to address this is, but we cannot leave the servers in an inconsistent
state between farms. For example :
backend site1
mode http
balance uri
hash-type consistent
server s1 127.0.0.1:8001 weight 10 track servers/s1
backend site2
mode http
balance uri
server s1 127.0.0.1:8001 weight 10 track servers/s1
backend site3
mode http
balance uri
hash-type consistent
server s1 127.0.0.1:8001 weight 10 track servers/s1
backend servers
server s1 127.0.0.1:8001 weight 10 check inter 1s
The weight change is applied on "servers/s1". It tries to propagate
to the servers tracking it, which are site1/s1, site2/s1 and site3/s1.
Let's say that "weight 50%" is requested. The servers are linked in
reverse-order, so the change is applied to "servers/s1", then to
"site3/s1", then to "site2/s1" and this one fails and rejects the
change. The change is aborted and never propagated to "site1/s1",
which keeps the server in a different state from "site3/s1". At the
very least, in case of error, the changes should probably be unrolled.
Also the error reported on the CLI (when changing from the CLI) simply says :
Backend is using a static LB algorithm and only accepts weights '0%' and '100%'.
Without more indications what the faulty backend is.
Let's revert this change for now, as initially feared it will definitely
cause more harm than good and at least needs to be revisited. It was never
backported to any stable branch so no backport is needed.
When agent-check or CLI command executes relative weight change this patch
propagates it to tracking server allowing grouping many backends running on
same server underneath. Additionaly in case with many src IPs many backends
can have shared state checker, so there won't be unnecessary health checks.
[wt: Note: this will induce some behaviour change on some setups]
IP*_BINDANY is not defined under this system thus it is
necessary to make those fields access since CONFIG_HAP_TRANSPARENT
is not defined.
[wt: problem introduced late in 1.8-dev. The same fix was also reported
by Steven Davidovitz]
Each time we generate a dynamic cookie, we try to make sure the same
cookie hasn't been generated for another server, it's very unlikely, but
it may happen.
We only have to check that for the servers in the same proxy, no, need to
check in others, plus the code was buggy and would always check in the
first proxy of the proxy list.
This patch fixes a bug which came with 5e57643 commit where server
default CRT filenames were initialized to the same value as server
default CRL filenames.
This patch adds 'no-agent-check' setting supported both by 'default-server'
and 'server' directives to disable an agent check for a specific server which would
have 'agent-check' set as default value (inherited from 'default-server'
'agent-check' setting), or, on 'default-server' lines, to disable 'agent-check' setting
as default value for any further 'server' declarations.
For instance, provided this configuration:
default-server agent-check
server srv1
server srv2 no-agent-check
server srv3
default-server no-agent-check
server srv4
srv1 and srv3 would have an agent check enabled contrary to srv2 and srv4.
We do not allocate anymore anything when parsing 'default-server' 'agent-check'
setting.
Before this patch, only 'server' directives could support 'disabled' setting.
This patch makes also 'default-server' directives support this setting.
It is used to disable a list of servers declared after a 'defaut-server' directive.
'enabled' new keyword has been added, both supported as 'default-server' and
'server' setting, to enable again a list of servers (so, declared after a
'default-server enabled' directive) or to explicitly enable a specific server declared
after a 'default-server disabled' directive.
For instance provided this configuration:
default-server disabled
server srv1...
server srv2...
server srv3... enabled
server srv4... enabled
srv1 and srv2 are disabled and srv3 and srv4 enabled.
This is equivalent to this configuration:
default-server disabled
server srv1...
server srv2...
default-server enabled
server srv3...
server srv4...
even if it would have been preferable/shorter to declare:
server srv3...
server srv4...
default-server disabled
server srv1...
server srv2...
as 'enabled' is the default server state.
This patch makes 'default-server' support 'addr' setting.
The code which was responsible of parsing 'server' 'addr' setting
has moved from parse_server() to implement a new parser
callable both as 'default-server' and 'server' 'addr' setting parser.
Should not break anything.
This patch makes 'default-server' directives support 'sni' settings.
A field 'sni_expr' has been added to 'struct server' to temporary
stores SNI expressions as strings during both 'default-server' and 'server'
lines parsing. So, to duplicate SNI expressions from 'default-server' 'sni' setting
for new 'server' instances we only have to "strdup" these strings as this is
often done for most of the 'server' settings.
Then, sample expressions are computed calling sample_parse_expr() (only for 'server'
instances).
A new function has been added to produce the same error output as before in case
of any error during 'sni' settings parsing (display_parser_err()).
Should not break anything.
Before this patch, only 'server' directives could support 'source' setting.
This patch makes also 'default-server' directives support this setting.
To do so, we had to extract the code responsible of parsing 'source' setting
arguments from parse_server() function and make it callable both
as 'default-server' and 'server' 'source' setting parser. So, the code is mostly
the same as before except that before allocating anything for 'struct conn_src'
members, we must free the memory previously allocated.
Should not break anything.
Before this patch, 'cookie' setting was only supported by 'server' directives.
This patch makes 'default-server' directive also support 'cookie' setting.
Should not break anything.
Before this path, 'observe' setting was only supported by 'server' directives.
This patch makes 'default-server' directives also support 'observe' setting.
Should not break anything.
Before this patch only 'server' directives could support 'redir' setting.
This patch makes also 'default-server' directives support 'redir' setting.
Should not break anything.
Before this patch only 'server' directives could support 'track' setting.
This patch makes 'default-server' directives also support this setting.
Should not break anything.
Before this patch 'check' setting was only supported by 'server' directives.
This patch makes also 'default-server' directives support this setting.
A new 'no-check' keyword parser has been implemented to disable this setting both
in 'default-server' and 'server' directives.
Should not break anything.
This patch makes 'default-server' directive support 'verifyhost' setting.
Note: there was a little memory leak when several 'verifyhost' arguments were
supplied on the same 'server' line.
This patch makes 'default-server' directive support 'send-proxy'
(resp. 'send-proxy-v2') setting.
A new keyword 'no-send-proxy' (resp. 'no-send-proxy-v2') has been added
to disable 'send-proxy' (resp. 'send-proxy-v2') setting both in 'server' and
'default-server' directives.
This patch makes 'default-server' directive support 'non-stick' setting.
A new keyword 'stick' has been added so that to disable
'non-stick' setting both in 'server' and 'default-server' directives.
This patch makes 'default-server' directive support 'check-send-proxy' setting.
A new keyword 'no-check-send-proxy' has been added so that to disable
'check-send-proxy' setting both in 'server' and 'default-server' directives.
At this time, only 'server' supported 'backup' keyword.
This patch makes also 'default-server' directive support this keyword.
A new keyword 'no-backup' has been added so that to disable 'backup' setting
both in 'server' and 'default-server' directives.
For instance, provided the following sequence of directives:
default-server backup
server srv1
server srv2 no-backup
default-server no-backup
server srv3
server srv4 backup
srv1 and srv4 are declared as backup servers,
srv2 and srv3 are declared as non-backup servers.
There is no reason to emit such an error message:
"'default-server' expects <name> and <addr>[:<port>] as arguments."
if less than two arguments are provided on 'default-server' lines.
This is a 'server' specific error message.
This adds a new "dynamic" keyword for the cookie option. If set, a cookie
will be generated for each server (assuming one isn't already provided on
the "server" line), from the IP of the server, the TCP port, and a secret
key provided. To provide the secret key, a new keyword as been added,
"dynamic-cookie-key", for backends.
Example :
backend bk_web
balance roundrobin
dynamic-cookie-key "bla"
cookie WEBSRV insert dynamic
server s1 127.0.0.1:80 check
server s2 192.168.56.1:80 check
This is a first step to be able to dynamically add and remove servers,
without modifying the configuration file, and still have all the load
balancers redirect the traffic to the right server.
Provide a way to generate session cookies, based on the IP address of the
server, the TCP port, and a secret key provided.
This change adds possibility to change agent-addr and agent-send directives
by CLI/socket. Now you can replace server's and their configuration without
reloading/restarting whole haproxy, so it's a step in no-reload/no-restart
direction.
Depends on #e9602af - agent-addr is implemented there.
Can be backported to 1.7.
This directive add possibility to set different address for agent-checks.
With this you can manage server status and weight from central place.
Can be backported to 1.7.
When a server doesn't resolve we don't know the address family so we
can't perform the basic protocol validations. However we know that we'll
ultimately resolve to AF_INET4 or AF_INET6 so the controls are OK. It is
important to proceed like this otherwise it will not be possible to start
with unresolved addresses.
Next patch will cause the port to disappear from the address field when servers
do not resolve so we need to take it from the separate field provided by
str2sa_range().
Keeping the address and the port in the same field causes a lot of problems,
specifically on the DNS part where we're forced to cheat on the family to be
able to keep the port. This causes some issues such as some families not being
resolvable anymore.
This patch first moves the service port to a new field "svc_port" so that the
port field is never used anymore in the "addr" field (struct sockaddr_storage).
All call places were adapted (there aren't that many).
The DNS code is written so as to support AF_UNSPEC to decide on the
server family based on responses, but unfortunately snr_resolution_cb()
considers it as invalid causing a DNS storm to happen when a server
arrives with this family.
This situation is not supposed to happen as long as unresolved addresses
are forced to AF_INET, but this will change with the upcoming fixes and
it's possible that it's not granted already when changing an address on
the CLI.
This fix must be backported to 1.7 and 1.6.
Now we exclusively use xprt_get(XPRT_RAW) instead of &raw_sock or
xprt_get(XPRT_SSL) for &ssl_sock. This removes a bunch of #ifdef and
include spread over a number of location including backend, cfgparse,
checks, cli, hlua, log, server and session.
Having it in the ifdef complicates certain operations which require
additional ifdefs just to access a member which could remain zero in
non-ssl cases. Let's move it out, it will not even increase the
struct size on 64-bit machines due to alignment.
Also mention that "set server" is preferred now. Note that these
were the last enable/disable commands in cli.c. Also remove the
now unused expect_server_admin() function.
Several CLI commands require a server, so let's have a function to
look this one up and prepare the appropriate error message and the
appctx's state in case of failure.
uint16_t instead of u_int16_t
None ISO fields of struct tm are not present, but
by zeroyfing it, on GNU and BSD systems tm_gmtoff
field will be set.
[wt: moved the memset into each of the date functions]
Now that it is possible to decide whether we prefer to use libc or the
state file to resolve the server's IP address and it is possible to change
a server's IP address at run time on the CLI, let's not restrict the reuse
of the address from the state file anymore to the DNS only.
The impact is that by default the state file will be considered first
(which matches its purpose) and only then the libc. This way any address
change performed at run time over the CLI will be preserved regardless
of DNS usage or not.
It is very common when validating a configuration out of production not to
have access to the same resolvers and to fail on server address resolution,
making it difficult to test a configuration. This option simply appends the
"none" method to the list of address resolution methods for all servers,
ensuring that even if the libc fails to resolve an address, the startup
sequence is not interrupted.
This will allow a server to automatically fall back to an explicit numeric
IP address when all other methods fail. The address is simply specified in
the address list.
Now that we have "init-addr none", it becomes possible to recover on
libc resolver's failures. Thus it's preferable not to alert nor fail
at the moment the libc is called, and instead process the failure at
the end of the list. This allows "none" to be set after libc to
provide a smooth fallback in case of resolver issues.
This new setting supports a comma-delimited list of methods used to
resolve the server's FQDN to an IP address. Currently supported methods
are "libc" (use the regular libc's resolver) and "last" (use the last
known valid address found in the state file).
The list is implemented in a 32-bit integer, because each init-addr
method only requires 3 bits. The last one must always be SRV_IADDR_END
(0), allowing to store up to 10 methods in a single 32 bit integer.
Note: the doc is provided at the end of this series.
WARNING: this is a MAJOR (and disruptive) change with previous HAProxy's
behavior: before, HAProxy never ever used to change a server administrative
status when the DNS resolution failed at run time.
This patch gives HAProxy the ability to change the administrative status
of a server to MAINT (RMAINT actually) when an error is encountered for
a period longer than its own allowed by the corresponding 'hold'
parameter.
IE if the configuration sets "hold nx 10s" and a server's hostname
points to a NX for more than 10s, then the server will be set to RMAINT,
hence in MAINTENANCE mode.
It will be important to help debugging some DNS resolution issues to
know why a server was marked down, so let's make the function support
a 3rd argument with an indication of the reason. Passing NULL will keep
the message as-is.
It's important to report in the server state change logs that RMAINT was
cleared, as it's not the regular maintenance mode, it's specific to name
resolution, and it's important to report the new state (which can be DRAIN
or READY).
Server addresses are not resolved anymore upon the first pass so that we
don't fail if an address cannot be resolved by the libc. Instead they are
processed all at once after the configuration is fully loaded, by the new
function srv_init_addr(). This function only acts on the server's address
if this address uses an FQDN, which appears in server->hostname.
For now the function does two things, to followup with HAProxy's historical
default behavior:
1. apply server IP address found in server-state file if runtime DNS
resolution is enabled for this server
2. use the DNS resolver provided by the libc
If none of the 2 options above can find an IP address, then an error is
returned.
All of this will be needed to support the new server parameter "init-addr".
For now, the biggest user-visible change is that all server resolution errors
are dumped at once instead of causing a startup failure one by one.
Right now there is an issue with the way the maintenance flags are
propagated upon startup. They are not propagate, just copied from the
tracked server. This implies that depending on the server's order, some
tracking servers may not be marked down. For example this configuration
does not work as expected :
server s1 1.1.1.1:8000 track s2
server s2 1.1.1.1:8000 track s3
server s3 1.1.1.1:8000 track s4
server s4 wtap:8000 check inter 1s disabled
It results in s1/s2 being up, and s3/s4 being down, while all of them
should be down.
The only clean way to process this is to run through all "root" servers
(those not tracking any other server), and to propagate their state down
to all their trackers. This is the same algorithm used to propagate the
state changes. It has to be done both to compute the IDRAIN flag and the
IMAINT flag. However, doing so requires that tracking servers are not
marked as inherited maintenance anymore while parsing the configuration
(and given that it is wrong, better drop it).
This fix also addresses another side effect of the bug above which is
that the IDRAIN/IMAINT flags are stored in the state files, and if
restored while the tracked server doesn't have the equivalent flag,
the servers may end up in a situation where it's impossible to remove
these flags. For example in the configuration above, after removing
"disabled" on server s4, the other servers would have remained down,
and not anymore with this fix. Similarly, the combination of IMAINT
or IDRAIN with their respective forced modes was not accepted on
reload, which is wrong as well.
This bug has been present at least since 1.5, maybe even 1.4 (it came
with tracking support). The fix needs to be backported there, though
the srv-state parts are irrelevant.
This commit relies on previous patch to silence warnings on startup.
We'll have to use srv_set_admin_flag() to propagate some server flags
during the startup, and we don't want the resulting actions to cause
warnings, logs nor e-mail alerts to be generated since we're just applying
the config or a state file. So let's condition these notifications to the
fact that we're starting.
CMAINT indicates that the server was *initially* disabled in the
configuration via the "disabled" keyword. FDRAIN indicates that the
server was switched to the DRAIN state from the CLI or the agent.
This it's perfectly valid to have both of them in the state file,
so the parser must not reject this combination.
This fix must be backported to 1.6.
There were seveal reports about the DRAIN state not being properly
restored upon reload.
It happens that the condition in the code does exactly the opposite
of what the comment says, and the comment is right so the code is
wrong.
It's worth noting that the conditions are complex here due to the 2
available methods to set the drain state (CLI/agent, and config's
weight). To paraphrase the updated comment in the code, there are
two possible reasons for FDRAIN to have been present :
- previous config weight was zero
- "set server b/s drain" was sent to the CLI
In the first case, we simply want to drop this drain state if the new
weight is not zero anymore, meaning the administrator has intentionally
turned the weight back to a positive value to enable the server again
after an operation. In the second case, the drain state was forced on
the CLI regardless of the config's weight so we don't want a change to
the config weight to lose this status. What this means is :
- if previous weight was 0 and new one is >0, drop the DRAIN state.
- if the previous weight was >0, keep it.
This fix must be backported to 1.6.
ipcpy() is used to replace an IP address with another one, but it
doesn't preserve the original port so all callers have to do it
manually while it's trivial to do there. Better do it inside the
function.
DNS servers don't return A or AAAA record if the query points to a CNAME
not resolving to the right type.
We know it because the last record of the response is a CNAME. We can
trigger a new query, switching to a new query type, handled by the layer
above.
New DNS response parser function which turn the DNS response from a
network buffer into a DNS structure, much easier for later analysis
by upper layer.
Memory is pre-allocated at start-up in a chunk dedicated to DNS
response store.
New error code to report a wrong number of queries in a DNS response.
This function can replace update_server_addr() where the need to change the
server's port as well as the IP address is required.
It performs some validation before performing each type of change.
Introduction of 3 new server flags to remember if some parameters were set
during configuration parsing.
* SRV_F_CHECKADDR: this server has a check addr configured
* SRV_F_CHECKPORT: this server has a check port configured
* SRV_F_AGENTADDR: this server has a agent addr configured
HAProxy used to deduce port used for health checks when parsing configuration
at startup time.
Because of this way of working, it makes it complicated to change the port at
run time.
The current patch changes this behavior and makes HAProxy to choose the
port used for health checking when preparing the check task itself.
A new type of error is introduced and reported when no port can be found.
There won't be any impact on performance, since the process to find out the
port value is made of a few 'if' statements.
This patch also introduces a new check state CHK_ST_PORT_MISS: this flag is
used to report an error in the case when HAProxy needs to establish a TCP
connection to a server, to perform a health check but no TCP ports can be
found for it.
And last, it also introduces a new stream termination condition:
SF_ERR_CHK_PORT. Purpose of this flag is to report an error in the event when
HAProxy has to run a health check but no port can be found to perform it.
Up to HAProxy 1.7-dev3, HAProxy used to use the first bind port from it's
local 'listen' section when no port is configured on the server.
IE, in the configuration below, the server port would be 25:
listen smtp
bind :25
server s1 1.0.0.1 check
This way of working is now obsolete and can be removed, furthermore it is not
documented!
This will make the possibility to change the server's port much easier.
Alexander Lebedev reported that the DNS parser crashes in 1.6 with a bus
error on Sparc when it receives a response. This is obviously caused by
some alignment issues. The issue can also be reproduced on ARMv5 when
setting /proc/cpu/alignment to 4 (which helps debugging).
Two places cause this crash in turn, the first one is when the IP address
from the packet is compared to the current one, and the second place is
when the address is assigned because an unaligned address is passed to
update_server_addr().
This patch modifies these places to properly use memcpy() and memcmp()
to manipulate the unaligned data.
Nenad Merdanovic found another set of places specific to 1.7 in functions
in_net_ipv4() and in_net_ipv6(), which are used to compare networks. 1.6
has the functions but does not use them. There we perform a temporary copy
to a local variable to fix the problem. The type of the function's argument
is wrong since it's not necessarily aligned, so we change it for a const
void * instead.
This fix must be backported to 1.6. Note that in 1.6 the code is slightly
different, there's no rec[] array, the pointer is used directly from the
buffer.
This is very useful in complex architecture systems where HAproxy
is balancing DB connections for example. We want to keep the maxconn
high in order to avoid issues with queueing on the LB level when
there is slowness on another part of the system. Example is a case of
an architecture where each thread opens multiple DB connections, which
if get stuck in queue cause a snowball effect (old connections aren't
closed, new ones cannot be established). These connections are mostly
idle and the DB server has no problem handling thousands of them.
Allowing us to dynamically set maxconn depending on the backend usage
(LA, CPU, memory, etc.) enables us to have high maxconn for situations
like above, but lowering it in case there are real issues where the
backend servers become overloaded (cache issues, DB gets hit hard).
dns_option struct pref_net field is an array of 5. The issue
here shows that pref_net_nb can go up to 5 as well which might lead
to read outside of this array.
Instead of repeating the type of the LHS argument (sizeof(struct ...))
in calls to malloc/calloc, we directly use the pointer
name (sizeof(*...)). The following Coccinelle patch was used:
@@
type T;
T *x;
@@
x = malloc(
- sizeof(T)
+ sizeof(*x)
)
@@
type T;
T *x;
@@
x = calloc(1,
- sizeof(T)
+ sizeof(*x)
)
When the LHS is not just a variable name, no change is made. Moreover,
the following patch was used to ensure that "1" is consistently used as
a first argument of calloc, not the last one:
@@
@@
calloc(
+ 1,
...
- ,1
)
In C89, "void *" is automatically promoted to any pointer type. Casting
the result of malloc/calloc to the type of the LHS variable is therefore
unneeded.
Most of this patch was built using this Coccinelle patch:
@@
type T;
@@
- (T *)
(\(lua_touserdata\|malloc\|calloc\|SSL_get_app_data\|hlua_checkudata\|lua_newuserdata\)(...))
@@
type T;
T *x;
void *data;
@@
x =
- (T *)
data
@@
type T;
T *x;
T *data;
@@
x =
- (T *)
data
Unfortunately, either Coccinelle or I is too limited to detect situation
where a complex RHS expression is of type "void *" and therefore casting
is not needed. Those cases were manually examined and corrected.
Commit baf9794 ("BUG/MINOR: tcpcheck: conf parsing error when no port
configured on server and first rule(s) is (are) COMMENT") was wrong, it
incorrectly implemented a list access by dereferencing a pointer of an
incorrect type resulting in checking the next element in the list. The
consequence is that it stops before the last comment instead of at the
last one and skips the first rule. In the end, rules starting with
comments are not affected, but if a sequence of checks directly starts
with connect, it is then skipped and this is visible when no port is
configured on the server line as the config refuses to load.
There was another occurence of the same bug a few lines below, both
of them were fixed. Tests were made on different configs and confirm
the new fix is OK.
This fix must be backported to 1.6.
the function server_parse_addr_change_request() contain an hardcoded
updater source "stats command". this function can be called from other
sources than the "stats command", so this patch make this argument
generic.
When the server address is changed, a message with unrequired '\n' or
'.' is displayed, like this:
[WARNING] 054/101137 (3229) : zzzz/s3 changed its IP from 127.0.0.1 to ::55 by stats command
.
This patch remove the '\n' which is sent before the '.'.
This patch must be backported in 1.6
This options prioritize th choice of an ip address matching a network. This is
useful with clouds to prefer a local ip. In some cases, a cloud high
avalailibility service can be announced with many ip addresses on many
differents datacenters. The latency between datacenter is not negligible, so
this patch permitsto prefers a local datacenter. If none address matchs the
configured network, another address is selected.
DNS selection preferences are actually declared inline in the
struct server. There are copied from the server struct to the
dns_resolution struct for each resolution.
Next patchs adds new preferences options, and it is not a good
way to copy all the configuration information before each dns
resolution.
This patch extract the configuration preference from the struct
server and declares a new dedicated struct. Only a pointer to this
new striuict will be copied before each dns resolution.
Servers state function save and apply server IP when DNS resolution is
enabled on a server.
Purpose is to prevent switching traffic from one server to an other one
when multiple IPs are returned by the DNS server for the A or AAAA
record.
That said, a bug in current code lead to erase the service port while
copying the IP found in the file into the server structure in HAProxy's
memory.
This patch fix this bug.
The bug was reported on the ML by Robert Samuel Newson and fix proposed
by Nenad Merdanovic.
Thank you both!!!
backport: can be backported to 1.6
A small configuration parsing error exists when no port is setup on the
server IP:port statement and the server's parameter 'port' is not set
and if the first tcp-check rule is a comment, like in the example below:
backend b
option tcp-check
tcp-check comment blah
tcp-check connect 8444
server s 127.0.0.1 check
In such case, an ALERT is improperly returned, despite this
configuration is valid and works.
The new code move the pointer to the first tcp-check rule which isn't a
comment before checking the presence of the port.
backport status: 1.6 and above
Current configuration parsing is permissive in such situation:
A server in a backend with no port conigured on the IP address
statement, no 'port' parameter configured and last rule of a tcp-check
is a CONNECT with no port.
The current code currently parses all the rules to validate a port is
well available, but it misses the last one, which means such
configuration is valid:
backend b
option tcp-check
tcp-check connect port 8444
tcp-check connect
server s 127.0.0.1 check
the second connect tentative is sent to port '0'...
Current patch fixes this by parsing the list the right way, including
the last rule.
backport status: 1.6 and above
fgets() can return NULL on error or when EOF occurs. This patch adds a
check of fgets() return value and displays a warning if the first line of
the server state file can not be read. Additionally, we make sure to close
the previously opened file descriptor.
Causes HAProxy to emit a static string to the agent on every check,
so that you can independently control multiple services running
behind a single agent port.
The status DNS_UPD_NAME_ERROR returned by dns_get_ip_from_response and
which means the queried name can't be found in the response was
improperly processed (fell into the default case).
This lead to a loop where HAProxy simply resend a new query as soon as
it got a response for this status and in the only case where such type
of response is the very first one received by the process.
This should be backported into 1.6 branch
Basically, it's ill-defined and shouldn't really be used going forward.
We can't guarantee that resolvers will do the 'legwork' for us and
actually resolve CNAMES when we request the ANY query-type. Case in point
(obfuscated, clearly):
PRODUCTION! ahayworth@secret-hostname.com:~$
dig @10.11.12.53 ANY api.somestartup.io
; <<>> DiG 9.8.4-rpz2+rl005.12-P1 <<>> @10.11.12.53 ANY api.somestartup.io
; (1 server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 62454
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 4, ADDITIONAL: 0
;; QUESTION SECTION:
;api.somestartup.io. IN ANY
;; ANSWER SECTION:
api.somestartup.io. 20 IN CNAME api-somestartup-production.ap-southeast-2.elb.amazonaws.com.
;; AUTHORITY SECTION:
somestartup.io. 166687 IN NS ns-1254.awsdns-28.org.
somestartup.io. 166687 IN NS ns-1884.awsdns-43.co.uk.
somestartup.io. 166687 IN NS ns-440.awsdns-55.com.
somestartup.io. 166687 IN NS ns-577.awsdns-08.net.
;; Query time: 1 msec
;; SERVER: 10.11.12.53#53(10.11.12.53)
;; WHEN: Mon Oct 19 22:02:29 2015
;; MSG SIZE rcvd: 242
HAProxy can't handle that response correctly.
Rather than try to build in support for resolving CNAMEs presented
without an A record in an answer section (which may be a valid
improvement further on), this change just skips ANY record types
altogether. A and AAAA are much more well-defined and predictable.
Notably, this commit preserves the implicit "Prefer IPV6 behavior."
Furthermore, ANY query type by default is a bad idea: (from Robin on
HAProxy's ML):
Using ANY queries for this kind of stuff is considered by most people
to be a bad practice since besides all the things you named it can
lead to incomplete responses. Basically a resolver is allowed to just
return whatever it has in cache when it receives an ANY query instead
of actually doing an ANY query at the authoritative nameserver. Thus
if it only received queries for an A record before you do an ANY query
you will not get an AAAA record even if it is actually available since
the resolver doesn't have it in its cache. Even worse if before it
only got MX queries, you won't get either A or AAAA
Commit e11cfcd ("MINOR: config: new backend directives:
load-server-state-from-file and server-state-file-name") introduced a bug
which can cause haproxy to crash upon startup by sending user-controlled
data in a format string when emitting a warning. Fix the way the warning
message is built to avoid this.
No backport is needed, this was introduced in 1.6-dev6 only.
Commit e11cfcd ("MINOR: config: new backend directives:
load-server-state-from-file and server-state-file-name") caused these
warnings when building with Clang :
src/server.c:1972:21: warning: comparison of unsigned expression < 0 is always false [-Wtautological-compare]
(srv_uweight < 0) || (srv_uweight > SRV_UWGHT_MAX))
~~~~~~~~~~~ ^ ~
src/server.c:1980:21: warning: comparison of unsigned expression < 0 is always false [-Wtautological-compare]
(srv_iweight < 0) || (srv_iweight > SRV_UWGHT_MAX))
~~~~~~~~~~~ ^ ~
Indeed, srv_iweight and srv_uweight are unsigned. Just drop the offending test.
This patch uses the start up of the health check task to also start
the warmup task when required.
This is executed only once: when HAProxy has just started up and can
be started only if the load-server-state-from-file feature is enabled
and the server was in the warmup state before a reload occurs.
This directive gives HAProxy the ability to use the either the global
server-state-file directive or a local one using server-state-file-name to
load server states.
The state can be saved right before the reload by the init script, using
the "show servers state" command on the stats socket redirecting output into
a file.
When a server is disabled in the configuration using the "disabled"
keyword, a single flag is positionned: SRV_ADMF_CMAINT (use to be
SRV_ADMF_FMAINT)..
That said, when providing the first version of this code, we also
changed the SRV_ADMF_MAINT mask to match any of the possible MAINT
cases: SRV_ADMF_FMAINT, SRV_ADMF_IMAINT, SRV_ADMF_CMAINT
Since SRV_ADMF_CMAINT is never (and is not supposed to be) altered at
run time, once a server has this flag set up, it can never ever be
enabled again using the stats socket.
In order to fix this, we should:
- consider SRV_ADMF_CMAINT as a simple flag to report the state in the
old configuration file (will be used after a reload to deduce the
state of the server in a new running process)
- enabling both SRV_ADMF_CMAINT and SRV_ADMF_FMAINT when the keyword
"disabled" is in use in the configuration
- update the mask SRV_ADMF_MAINT as it was before, to only match
SRV_ADMF_FMAINT and SRV_ADMF_IMAINT.
The following patch perform the changes above.
It allows fixing the regression without breaking the way the up coming
feature (seamless server state accross reloads) is going to work.
Note: this is 1.6-only, no backport needed.
There are two types of retries when performing a DNS resolution:
1. retry because of a timeout
2. retry of the full sequence of requests (query types failover)
Before this patch, the 'resolution->try' counter was incremented
after each send of a DNS request, which does not cover the 2 cases
above.
This patch fix this behavior.
Some DNS response may be valid from a protocol point of view but may not
contain any IP addresses.
This patch gives a new flag to the function dns_get_ip_from_response to
report such case.
It's up to the upper layer to decide what to do with this information.
Some DNS responses may be valid from a protocol point of view, but may
not contain any information considered as interested by the requester..
Purpose of the flag DNS_RESP_NO_EXPECTED_RECORD introduced by this patch is
to allow reporting such situation.
When this happens, a new DNS query is sent with a new query type.
For now, the function only expect A and AAAA query types which is enough
to cover current cases.
In a next future, it will be up to the caller to tell the function which
query types are expected.
The server's host name picked for resolution was incorrect, it did not
skip the address family specifier, did not resolve environment variables,
and messed up with the optional trailing colon.
Instead, let's get the fqdn returned by str2sa_range() and use that
exclusively.
The function does a bunch of things among which resolving environment
variables, skipping address family specifiers and trimming port ranges.
It is the only one which sees the complete host name before trying to
resolve it. The DNS resolving code needs to know the original hostname,
so we modify this function to optionally provide it to the caller.
Note that the function itself doesn't know if the host part was a host
or an address, but str2ip() knows that and can be asked not to try to
resolve. So we first try to parse the address without resolving and
try again with resolving enabled. This way we know if the address is
explicit or needs some kind of resolution.
In the first version of the DNS resolver, HAProxy sends an ANY query
type and in case of issue fails over to the type pointed by the
directive in 'resolve-prefer'.
This patch allows the following new failover management:
1. default query type is still ANY
2. if response is truncated or in error because ANY is not supported by
the server, then a fail over to a new query type is performed. The
new query type is the one pointed by the directive 'resolve-prefer'.
3. if no response or still some errors occurs, then a query type fail over
is performed to the remaining IP address family.
This patch introduces a new internal response state about the analysis
of a DNS response received by a server.
It is dedicated to report to above layer that the response is
'truncated'.
Under certain circonstance (a configuration with many servers relying on
DNS resolution and one of them triggering the replay of a request
because of a timeout or invalid response to an ANY query), HAProxy could
end up in an infinite loop over the currently supposed running DNS
queries.
This was caused because the FIFO list of running queries was improperly
updated in snr_resolution_error_cb. The head of the list was removed
instead of the resolution in error, when moving the resolution to the
end of the list.
In the mean time, a LIST_DEL statement is removed since useless. This
action is already performed by the dns_reset_resolution function.
First DNS resolution is supposed to be triggered by first health check,
which is not the case with current code.
This patch fixes this behavior by setting the
resolution->last_resolution time to 0 instead of now_ms when parsing
server's configuration at startup.
This was the first transparent proxy technology supported by haproxy
circa 2005 but it was obsoleted in 2007 by Tproxy 4.0 which removed a
lot of the earlier versions' shortcomings and was finally merged into
the kernel. Since nobody has been using cttproxy for many years now
and nobody has even just tried to compile the files, it's time to
remove it. The doc was updated as well.
The newly created server flag SRV_ADMF_CMAINT means that the server is
in 'disabled' mode because of configuration statement 'disabled'.
The flag SRV_ADMF_FMAINT should not be set anymore in such case and is
reserved only when the server is Forced in maintenance mode from the
stats socket.
These ones are considered safe as they have already been reused.
They will be useful in "aggressive" and "always" http-reuse modes
in order to place the first request of a connection with the least
risk.
