From f61fd8b8e0106d25c228f3b4586598f91a23d3b2 Mon Sep 17 00:00:00 2001
From: Guillermo Facundo Colunga <guillermo.facundo.colunga@cern.ch>
Date: Tue, 21 Jan 2025 16:32:49 +0100
Subject: [PATCH] [MONIT-4105] docs/metrics: include documentation about
 relabelings

---
 docs/metrics.md | 40 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 40 insertions(+)

diff --git a/docs/metrics.md b/docs/metrics.md
index ced61aa..938a833 100644
--- a/docs/metrics.md
+++ b/docs/metrics.md
@@ -82,6 +82,46 @@ metrics:
 
 This configuration will create a service in your cluster named `it-monit-metrics-collector-pushgateway`. In this service there is a port named `http` (9091) where you can push your metrics. If you need to push metrics from outside the cluster you only need to enable the ingress and point the corresponding dns records to your cluster ingress nodes.
 
+### E. Metrics Drop and Transformations
+With the recent updates, it is now possible to configure user-provided relabelings for various Kubernetes components monitored by Prometheus. This enhancement provides greater flexibility in transforming, dropping, or modifying metrics based on user-defined criteria.
+
+All the components can be configured as follows, applied under its corresponding key:
+
+```yaml
+relabelings:
+  - action: drop
+    sourceLabels: [__name__]
+    regex: ".*_unwanted_metric"
+  - action: drop
+    sourceLabels: [__name__]
+    regex: ".*_unwanted_metric_two"
+```
+
+Here is the list of components and the YAML key that corresponds to it:
+  - api server: `metrics.apiServer.serviceMonitor.relabelings`
+  - coredns: `metrics.coredns.serviceMonitor.relabelings`
+  - ectd: `metrics.etcd.serviceMonitor.relabelings`
+  - ingress nginx: `metrics.ingress.nginx.serviceMonitor.relabelings`
+  - kube state: `metrics.kubeState.serviceMonitor.relabelings`
+  - kube controller: `metrics.kubeController.serviceMonitor.relabelings`
+  - kubelet: `metrics.kubelet.serviceMonitor.relabelings`
+  - kubeproxy: `metrics.kubeProxy.serviceMonitor.relabelings`
+  - node exporter: `metrics.nodeExporter.serviceMonitor.relabelings`
+  - scheduler: `metrics.kubeScheduler.serviceMonitor.relabelings`
+
+Also, there is a general option that allows you to apply the relabeling option generally. The difference is that with previous options Prometheus will not store locally the metrics (saving memory), but user will need to know which component creates which metric. With the alternate method Prometheus will store the metrics but not forward them. In this case users do not need to know from where the metric is gathered.
+
+```yaml
+metrics:
+  prometheus:
+    server:
+      relabelings:
+        - action: drop
+          sourceLabels: [__name__]
+          regex: ".*_unwanted_metric"
+```
+
+
 ## 4 . Further Customizations
 
 You can further customize metrics collection with the following settings:
-- 
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