update readme

CONTRIBUTING.md

@@ -0,0 +1,13 @@
+# Contributing
+
+To regenerate mocks:
+
+```shell
+mockgen -source=internal/syncer.go -package=internal -destination=internal/syncermock_test.go
+```
+
+To make a release:
+
+```shell
+TAG=x.x.x && git tag -a ${TAG} -m "make ${TAG} release" && git push --tags
+```

README.md

@@ -1,15 +1,86 @@
-# cortex-rule-watcher
+# cortex-rule-watcher <a href="https://hub.docker.com/r/slamdev/cortex-rule-watcher"><img alt="status" src="https://img.shields.io/docker/v/slamdev/cortex-rule-watcher"></a>
 
-Cortex ruler sidecar to sync PrometheusRule resources
+Ruler component in [Cortex](https://github.com/cortexproject/cortex)/[Mimir](https://github.com/grafana/mimir) 
+does not support rules extraction from [PrometheusRule](https://github.com/prometheus-operator/prometheus-operator/blob/main/Documentation/user-guides/alerting.md#prometheusrule-labelling) resources.
 
-To regenerate mocks:
+**cortex-rule-watcher** can help you with that. It can be added as a sidecar container to the ruler deployment and
+will watch for the changes in PrometheusRule resources in the cluster. As soon as it sees a change in PrometheusRule resource,
+it will dump the PrometheusRule spec to the file, that will be synced by ruler component.
 
-```shell
-mockgen -source=internal/syncer.go -package=internal -destination=internal/syncermock_test.go
+[Click to see a full example](example/example.yaml)
+
+Or use this configuration for [mimir helm chart](https://github.com/grafana/helm-charts/tree/mimir-distributed-2.0.7/charts/mimir-distributed):
+
+```yaml
+ruler:
+  extraContainers:
+    - name: cortex-rule-watcher
+      args:
+        - --rule-path=/local-rules
+      image: slamdev/cortex-rule-watcher:latest
+      imagePullPolicy: Always
+      ports:
+        - name: http-health
+          containerPort: 8081
+        - name: http-metrics
+          containerPort: 8082
+      livenessProbe:
+        httpGet:
+          path: /healthz
+          port: 8081
+        initialDelaySeconds: 15
+        periodSeconds: 20
+      readinessProbe:
+        httpGet:
+          path: /readyz
+          port: 8081
+        initialDelaySeconds: 5
+        periodSeconds: 10
+      resources:
+        requests:
+          cpu: 10m
+          memory: 16Mi
+      volumeMounts:
+        - name: rules
+          mountPath: /local-rules
+  extraVolumes:
+    - name: rules
+      emptyDir: { }
+  extraVolumeMounts:
+    - name: rules
+      mountPath: /ruler/fake
+  extraArgs:
+    ruler-storage.backend: local
+    ruler-storage.local.directory: /ruler
 ```
 
-To make a release:
+Besides that you have to have a cluster role and binding:
 
-```shell
-TAG=x.x.x && git tag -a ${TAG} -m "make ${TAG} release" && git push --tags
+```yaml
+apiVersion: rbac.authorization.k8s.io/v1
+kind: ClusterRole
+metadata:
+  name: mimir-distributed-cortex-rule-watcher
+rules:
+  - apiGroups:
+      - monitoring.coreos.com
+    resources:
+      - prometheusrules
+    verbs:
+      - get
+      - list
+      - watch
+---
+apiVersion: rbac.authorization.k8s.io/v1
+kind: ClusterRoleBinding
+metadata:
+  name: mimir-distributed-cortex-rule-watcher
+roleRef:
+  apiGroup: rbac.authorization.k8s.io
+  kind: ClusterRole
+  name: mimir-distributed-cortex-rule-watcher
+subjects:
+  - kind: ServiceAccount
+    name: mimir-distributed
+    namespace: monitoring
 ```