3023e98199
Since the commit dcb696cd3 ("MEDIUM: resolvers: hash the records before
inserting them into the tree"), When several records are found in a DNS
answer, the round robin selection over these records is no longer performed.
Indeed, before a list of records was used. To ensure each records was
selected one after the other, at each selection, the first record of the
list was moved at the end. When this list was replaced bu a tree, the same
mechanism was preserved. However, the record is indexed using its key, a
hash of the record. So its position never changes. When it is removed and
reinserted in the tree, its position remains the same. When we walk though
the tree, starting from the root, the records are always evaluated in the
same order. So, even if there are several records in a DNS answer, the same
IP address is always selected.
It is quite easy to trigger the issue with a do-resolv action.
To fix the issue, the node to perform the next selection is now saved. So
instead of restarting from the root each time, we can restart from the next
node of the previous call.
Thanks to Damien Claisse for the issue analysis and for the reproducer.
This patch should fix the issue #3116. It must be backported as far as 2.6.
HAProxy
HAProxy is a free, very fast and reliable reverse-proxy offering high availability, load balancing, and proxying for TCP and HTTP-based applications.
Installation
The INSTALL file describes how to build HAProxy. A list of packages is also available on the wiki.
Getting help
The discourse and the mailing-list are available for questions or configuration assistance. You can also use the slack or IRC channel. Please don't use the issue tracker for these.
The issue tracker is only for bug reports or feature requests.
Documentation
The HAProxy documentation has been split into a number of different files for ease of use. It is available in text format as well as HTML. The wiki is also meant to replace the old architecture guide.
Please refer to the following files depending on what you're looking for:
- INSTALL for instructions on how to build and install HAProxy
- BRANCHES to understand the project's life cycle and what version to use
- LICENSE for the project's license
- CONTRIBUTING for the process to follow to submit contributions
The more detailed documentation is located into the doc/ directory:
- doc/intro.txt for a quick introduction on HAProxy
- doc/configuration.txt for the configuration's reference manual
- doc/lua.txt for the Lua's reference manual
- doc/SPOE.txt for how to use the SPOE engine
- doc/network-namespaces.txt for how to use network namespaces under Linux
- doc/management.txt for the management guide
- doc/regression-testing.txt for how to use the regression testing suite
- doc/peers.txt for the peers protocol reference
- doc/coding-style.txt for how to adopt HAProxy's coding style
- doc/internals for developer-specific documentation (not all up to date)
License
HAProxy is licensed under GPL 2 or any later version, the headers under LGPL 2.1. See the LICENSE file for a more detailed explanation.