It is now possible to filter the metrics on their name, by listing
explicitly metrics to dump or on the opposite to exclude only some metrics
from the dump. To do so, a comma-separated list of metrics must be
specified. If a name is preceded by a minus (-), the metric is excluded from
the dump. If at least one metric is specified to be explicitly dumped, all
metrics are no longer dumped, but only those explicitly listed.
The list is specified via one or more "metrics" parameters in the uri
query-string. For insance:
# Dumped all metrics, except "haproxy_server_check_status"
/metrics?metrics=-haproxy_server_check_status
# Only dump frontends, backends and servers status
/metrics?metrics=haproxy_frontend_status,haproxy_backend_status,haproxy_server_status
Included and Excluded metrics can be mixed. Only the intersection will be
dumped.
This patch should fix the issue #770.
This patch adds a dump loop on the registered modules. It is very similar to
other dump loops. When a module registered, a implicit scope is created with
the module's name. It means a module name must be unique. It also means,
metrics dump of modules can be filtered via the "scope" parameter.
In this patch we add a registration mechanism for modules. To do so, a
module must defined the "promex_module" structure. The dump itself will be
based on 2 contexts. One for all the dump and another one for each metric
time-series. These contexts are used as restart points when the dump is
interrupted.
Modules must also implement 6 callback functions:
* start_metric_dump(): It is an optional callback function. If defined, it
is responsible to initialize the dump context use
as the first restart point.
* stop_metric_dump(): It is an optional callback function. If defined, it
is responsible to deinit the dump context.
* metric_info(): This one is mandatory. It returns the info about the
metric: name, type and flags and descrition.
* start_ts(): This one is mandatory, it initializes the context for a time
series for a given metric. This context is the second
restart point.
* next_ts(): This one is mandatory. It interates on time series for a
given metrics. It is also responsible to handle end of a
time series and deinit the context.
* fill_ts(): It fills info on the time series for a given metric : the
labels and the value.
In addition, a module must set its name and declare the number of metrics is
exposed.
