Merge pull request #4785 from ti-mo/master

Add documentation for new marathon-sd functionality

docs/configuration/configuration.md

@@ -874,8 +874,12 @@ tls_config:
 
 By default every app listed in Marathon will be scraped by Prometheus. If not all
 of your services provide Prometheus metrics, you can use a Marathon label and
-Prometheus relabeling to control which instances will actually be scraped. Also
-by default all apps will show up as a single job in Prometheus (the one specified
+Prometheus relabeling to control which instances will actually be scraped.
+See [the Prometheus marathon-sd configuration file](/documentation/examples/prometheus-marathon.yml)
+for a practical example on how to set up your Marathon app and your Prometheus
+configuration.
+
+By default, all apps will show up as a single job in Prometheus (the one specified
 in the configuration file), which can also be changed using relabeling.
 
 ### `<nerve_sd_config>`

documentation/examples/prometheus-marathon.yml

@@ -0,0 +1,60 @@
+# A example scrape configuration for running Prometheus on a Marathon
+# (or DC/OS) cluster.
+
+scrape_configs:
+  
+  # Make Prometheus scrape itself for metrics.
+  - job_name: 'prometheus'
+    static_configs:
+    - targets: ['localhost:9090']
+
+  # Discover Marathon services to scrape.
+  - job_name: 'marathon'
+
+    # Scrape Marathon itself to discover new services every minute.
+    marathon_sd_configs:
+      - servers:
+        - http://marathon.mesos:8080
+        refresh_interval: 60s
+
+    relabel_configs:
+
+      # Only scrape targets that have a port label called 'metrics' specified on a port
+      # in their app definitions. Example using a port mapping (container or bridge networking):
+      #
+      #  "portMappings": [
+      #    {
+      #      "containerPort": 9091,
+      #      "name": "prometheus",
+      #      "labels": {
+      #        "metrics": "/metrics"
+      #      }
+      #    }
+      #  ]
+      #
+      # Or, in case your service uses host networking, using a port definition:
+      #
+      #  "portDefinitions" : [
+      #    {
+      #      "port" : 9091,
+      #      "name" : "prometheus",
+      #      "labels": {
+      #        "metrics": "/metrics"
+      #      }
+      #    }
+      #  ]
+
+      # Match a slash-prefixed string either in a portMapping or a portDefinition label.
+      - source_labels: [__meta_marathon_port_mapping_label_metrics,__meta_marathon_port_definition_label_metrics]
+        regex: (\/.+;|;\/.+)
+        action: keep
+
+      # If a portMapping 'metrics' label is set, use the label value as the URI to scrape.
+      - source_labels: [__meta_marathon_port_mapping_label_metrics]
+        regex: (\/.+)
+        target_label: __metrics_path__
+      
+      # If a portDefinition 'metrics' label is set, use the label value as the URI to scrape.
+      - source_labels: [__meta_marathon_port_definition_label_metrics]
+        regex: (\/.+)
+        target_label: __metrics_path__