Add /_admin/metrics/v2 DocuBlock (#14324)

* Add deprecation warning to old metrics endpoint

* Add DocuBlock for /_admin/metrics/v2

* Try to make plain curl examples shortable

* Strip whitespace from line

* Update get_admin_metrics_v2.md

Co-authored-by: Vadim Kondratyev <vadim@arangodb.com>

Documentation/DocuBlocks/Rest/Administration/get_admin_metrics.md

@@ -4,6 +4,13 @@
 
 @RESTHEADER{GET /_admin/metrics, Read the metrics, getMetrics}
 
+@HINTS
+{% hint 'warning' %}
+This endpoint should no longer be used. It is deprecated from version 3.8.0 on.
+Use `/_admin/metrics/v2` instead, which provides the data exposed by this API
+and a lot more.
+{% endhint %}
+
 @RESTQUERYPARAMETERS
 
 @RESTQUERYPARAM{serverId,string,optional}

Documentation/DocuBlocks/Rest/Administration/get_admin_metrics_v2.md

@@ -0,0 +1,46 @@
+
+@startDocuBlock get_admin_metrics_v2
+@brief return the current instance metrics
+
+@RESTHEADER{GET /_admin/metrics/v2, Read the metrics, getMetricsV2}
+
+@RESTQUERYPARAMETERS
+
+@RESTQUERYPARAM{serverId,string,optional}
+Returns metrics of the specified server. If no serverId is given, the asked
+server will reply. This parameter is only meaningful on Coordinators.
+
+@RESTDESCRIPTION
+Returns the instance's current metrics in Prometheus format. The
+returned document collects all instance metrics, which are measured
+at any given time and exposes them for collection by Prometheus.
+
+The document contains different metrics and metrics groups dependent
+on the role of the queried instance. All exported metrics are
+published with the prefix `arangodb_` or `rocksdb_` to distinguish them from
+other collected data.
+
+The API then needs to be added to the Prometheus configuration file
+for collection.
+
+@RESTRETURNCODES
+
+@RESTRETURNCODE{200}
+Metrics were returned successfully.
+
+@RESTRETURNCODE{404}
+The metrics API may be disabled using `--server.export-metrics-api false`
+setting in the server. In this case, the result of the call indicates the API
+to be not found.
+
+@EXAMPLES
+
+@EXAMPLE_ARANGOSH_RUN{RestAdminMetricsV2}
+    var url = "/_admin/metrics/v2";
+    var response = logCurlRequest('GET', url);
+
+    assert(response.code === 200);
+
+    logPlainResponse(response);
+@END_EXAMPLE_ARANGOSH_RUN
+@endDocuBlock

Documentation/Scripts/codeBlockReader.py

@@ -144,7 +144,7 @@ def example_content(filepath, fh, tag, blockType, placeIntoFilePath):
         curlState = CURL_STATE_CMD
       elif curlState == CURL_STATE_CMD and line.startswith("HTTP/"):
         curlState = CURL_STATE_HEADER
-      elif curlState == CURL_STATE_HEADER and line.startswith("{"):
+      elif curlState == CURL_STATE_HEADER and len(line.strip()) == 0:
         curlState = CURL_STATE_BODY
 
       if curlState == CURL_STATE_CMD or curlState == CURL_STATE_HEADER:
@@ -241,8 +241,8 @@ def example_content(filepath, fh, tag, blockType, placeIntoFilePath):
       hideText
       ))
   fh.write("</div>\n")
-    
-  if shortable:    
+
+  if shortable:
     fh.write("<div id=\"%s\" onclick=\"%s\">\n" % (shortTag, shortToggle))
     if blockType != "AQL" and blockType != "EXPLAIN":
       fh.write("<pre>\n")