prometheus_stats: added its details

Signed-off-by: Hofi <hofione@gmail.com>

Author: HofiOne

_data/external_links.yml

@@ -1107,6 +1107,11 @@ postgresql:
   url: https://www.postgresql.org/docs/current/runtime-config-logging.html#RUNTIME-CONFIG-LOGGING-CSVLOG
   title: [ "PostgreSQL" ]
 
+prometheus-scraper:
+  id: prometheus-scraper
+  url: https://prometheus.io/docs/prometheus/latest/getting_started/#configure-prometheus-to-monitor-the-sample-targets
+  title: [ "/[Pp]rometheus [Ss]craper/" ]
+
 qbittorrent:
   id: qbittorrent
   url: https://www.qbittorrent.org/

_data/link_aliases.yml

@@ -99,6 +99,9 @@ adm-about-glossary#bsd-syslog-protocol:
 adm-about-glossary#ietf-syslog-protocol:
   aliases: [ "IETF-syslog protocol", "IETF-syslog" ]
 
+adm-src-prometheus-stats:
+  aliases: [ "prometheus-stats-dont-log()" ]
+
 adm-src-wild:
   aliases: [ "/wildcard-file(?:\\(\\))? source[s]?/" ]
 

_data/navigation.yml

@@ -236,6 +236,11 @@ admin-guide-nav:
       subnav:
       - title: "program() source options"
         url: /admin-guide/060_Sources/130_Program/000_Program_source_options
+    - title: "prometheus-stats"
+      url: /admin-guide/060_Sources/135_Prometheus/README
+      subnav:
+      - title: "prometheus-stats() source options"
+        url: /admin-guide/060_Sources/135_Prometheus/000_prometheus-stats_source_options
     - title: "python"
       url: /admin-guide/060_Sources/140_Python/README
       subnav:

doc/_admin-guide/060_Sources/135_Prometheus/000_prometheus-stats_source_options.md

@@ -0,0 +1,38 @@
+---
+title: prometheus-stats() source options
+id: adm-src-prometheus-stats-opt
+description: >-
+    The prometheus-stats() sources directly can serve the output of syslog-ng-ctl stats and syslog-ng-ctl query to a Prometheus Scraper. Unlike the prometheus-stats-dont-log() that suppresses log messages from incoming scraper requests, the prometheus-stats() logs the unparsed messages, storing incoming scraper HTTP requests in the MSG field.
+---
+
+Technically, both sources are specialized versions of the network() source. See the network() source options for details.
+
+These drivers have the following additional options:
+
+## stat-type()
+
+|Accepted values:| query \| stats |
+|Default:        | stats |
+
+*Description:* The stat type you wish to provide in the response to a Prometheus Scraper request, just like for the syslog-ng-ctl command line tool.
+
+## stat-query()
+
+|Accepted values:| regular expression |
+|Default:        |  |
+
+*Description:* The query regex string that can be used to filter the output of a `query` type request.
+
+## scrape-freq-limit()
+
+|Accepted values:| number |
+|Default:        | 0 |
+
+*Description:* Limits the frequency of repeated scraper requests to the specified number of seconds. Any repeated request within this period will be ignored. A value of 0 means no limit.
+
+## single-instance()
+
+|Accepted values:| yes \| no |
+|Default:        | no |
+
+*Description:* If set to `yes` only one scraper connection and request will be allowed at once.

doc/_admin-guide/060_Sources/135_Prometheus/README.md

@@ -0,0 +1,33 @@
+---
+title: 'prometheus-stats: Providing various statistics information to a Prometheus Scraper'
+short_title: prometheus-stats
+id: adm-src-prometheus-stats
+description: >-
+    The prometheus-stats() and prometheus-stats-dont-log() sources can directly serve the output of
+    syslog-ng-ctl stats and syslog-ng-ctl query to a Prometheus Scraper.
+---
+
+Example usage:
+
+``` config
+@version: 4.9
+@include "scl.conf"
+
+source s_prometheus_stat {
+    prometheus-stats-dont-log(
+        ip("0.0.0.0")
+        port(8080)
+        stat-type("query")
+        stat-query("*")
+        scrape-freq-limit(30)
+        single-instance(yes)
+    );
+};
+
+log {
+    source(s_prometheus_stat);
+};
+```
+
+>**NOTE:** A destination is not required for this to work; the `prometheus-stats()` sources will respond to the scraper regardless of whether a destination is present in the log path.
+{: .notice--info}

doc/_admin-guide/150_Statistics_of_syslog-ng/README.md

@@ -12,8 +12,7 @@ description: >-
 
 ## Recommended: Structured, selective methods
 
-- Using the syslog-ng-ctl
-    query command.
+- Using the syslog-ng-ctl query command.
 
     For further information about using syslog-ng-ctl commands, see
     The {{ site.product.short_name }} manual pages.