Docs metrics configuration (#1850)

docs/developers/metrics-configuration.md

@@ -0,0 +1,79 @@
+## Metrics configuration and how to import metrics of [Prebid server](https://docs.prebid.org/prebid-server/versions/pbs-versions-go.html) to [Grafana](https://grafana.com/) through [Prometheus](https://prometheus.io/) stack.
+     
+#### These are the parameters that are capable for metrics collection 
+
+- PBS_METRICS_PROMETHEUS_PORT=9100 - default is 0.
+
+If PBS_METRICS_PROMETHEUS_PORT is null, your [Prebid server](https://docs.prebid.org/prebid-server/versions/pbs-versions-go.html) won't collect any metrics.
+
+- PBS_METRICS_PROMETHEUS_NAMESPACE=prebid - default is empty.
+
+PBS_METRICS_PROMETHEUS_NAMESPACE - this is responsable for the primary prefix added to your metrics to ensure uniqueness within your cluster.
+
+- PBS_METRICS_PROMETHEUS_SUBSYSTEM=server - default is empty.
+
+PBS_METRICS_PROMETHEUS_SUBSYSTEM - this is a secondary prefix added to metrics to ensure uniqueness.
+
+- PBS_METRICS_DISABLED_METRICS_ADAPTER_CONNECTIONS_METRICS=false - default is true.
+
+PBS_METRICS_DISABLED_METRICS_ADAPTER_CONNECTIONS_METRICS - If this flag is set to true you won't get any bidder http connection adapter metrics (e.g. number of new vs reused connections) but you'll still get other adapter metrics.
+
+#### If you're going to get metrics though [Prometheus](https://prometheus.io/) and [Prometheus](https://prometheus.io/) stack has been already installed, you have several options, please chose one:
+
+- change environments into code (bad way).
+
+- create pbs.yaml if it hasn't been already created (It works, but not flexible).
+
+- input the parameters into global environments (Highly recommend you to use this way also it's reliable).
+
+#### Finally, when you fill in your credentials of metrics, please, run:
+
+ - build your app 
+```bash
+go build .
+```
+ - run the server
+```bash
+./prebid-server
+```
+
+#### Make sure that an application returns any metrics - `http://localhost:9100/`, if not, please check your names of environment and recompile again.
+
+#### Add your host and port into prometheus.yml file on the instance of your [Prometheus](https://prometheus.io/).
+
+```yaml
+global:
+  scrape_interval: 15s
+  evaluation_interval: 15s
+
+  external_labels:
+    monitor: 'docker-host-alpha'
+
+rule_files:
+  - "alert.rules"
+
+scrape_configs:
+  - job_name: 'prometheus'
+    scrape_interval: 10s
+    static_configs:
+      - targets: [ 'prometheus-host:9090']
+
+  - job_name: 'prebidserver-metrics'
+    scrape_interval: 10s
+    static_configs:
+      - targets: ['prebidserver-host:9100' ]
+alerting:
+  alertmanagers:
+    - scheme: http
+      static_configs:
+        - targets:
+            - 'localhost:9093'
+```
+
+#### Import data source as [Prometheus](https://prometheus.io/) into [Grafana](https://grafana.com/)
+
+Just fill in host and port of [Prometheus](https://prometheus.io/)
+
+![img_grafana.png](images/img_grafana.png)
+
+#### In that case [Prebid server](https://docs.prebid.org/prebid-server/versions/pbs-versions-go.html) uses [package](https://github.com/prometheus/client_golang) in our case it works as [Node exporter](https://github.com/prometheus/node_exporter). Therefore, here is described only how to connect [Prebid server](https://docs.prebid.org/prebid-server/versions/pbs-versions-go.html) connection with [Prometheus](https://prometheus.io/). Also, if you are interested in [Prometheus](https://prometheus.io/) and want to dig deep, follow [docs](https://prometheus.io/docs/introduction/overview/).