Monitor Policy Controller

Policy Controller uses Prometheus to collect and show metrics related to its processes.

You can also configure Cloud Monitoring to pull custom metrics from Prometheus. Then you can see custom metrics in both Prometheus and Monitoring. For more information, see Using Prometheus.

Scraping the metrics

All Prometheus metrics are available for scraping at port 8675. Before you can scrape metrics, you need to configure your cluster for Prometheus in one of two ways. Either:

Follow the Prometheus documentation to configure your cluster for scraping, or

Use the Prometheus Operator along with the following manifests, which scrape all Anthos Config Management metrics every 10 seconds.

Create a temporary directory to hold the manifest files.
```
mkdir acm-monitor
cd acm-monitor
```
Download the Prometheus Operator manifest from the CoreOS repository. repository, using the curl command:
```
curl -o bundle.yaml https://raw.githubusercontent.com/coreos/prometheus-operator/master/bundle.yaml
```
This manifest is configured to use the default namespace, which is not recommended. The next step modifies the configuration to use a namespace called monitoring instead. To use a different namespace, substitute it where you see monitoring in the remaining steps.

Create a file to update the namespace of the ClusterRoleBinding in the bundle above.

# patch-crb.yaml
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
  name: prometheus-operator
subjects:
- kind: ServiceAccount
  name: prometheus-operator
  namespace: monitoring # we are patching from default namespace

Create a kustomization.yaml file that applies the patch and modifies the namespace for other resources in the manifest.
```
# kustomization.yaml
resources:
- bundle.yaml

namespace: monitoring

patchesStrategicMerge:
- patch-crb.yaml
```
Create the monitoring namespace. You can use a different name for the namespace, but if you do, also change the value of namespace in the YAML manifests from the previous steps.
```
kubectl create namespace monitoring
```

Apply the kustomized manifest using the following commands:

kubectl apply -k .

until kubectl get customresourcedefinitions servicemonitors.monitoring.coreos.com ; \
do date; sleep 1; echo ""; done

The second command blocks until the CRDs are available on the cluster.

Create the manifest for the resources necessary to configure a Prometheus server which scrapes metrics from Anthos Config Management.

# acm.yaml
apiVersion: v1
kind: ServiceAccount
metadata:
  name: prometheus-acm
  namespace: monitoring
---
apiVersion: rbac.authorization.k8s.io/v1beta1
kind: ClusterRole
metadata:
  name: prometheus-acm
rules:
- apiGroups: [""]
  resources:
  - nodes
  - services
  - endpoints
  - pods
  verbs: ["get", "list", "watch"]
- apiGroups: [""]
  resources:
  - configmaps
  verbs: ["get"]
- nonResourceURLs: ["/metrics"]
  verbs: ["get"]
---
apiVersion: rbac.authorization.k8s.io/v1beta1
kind: ClusterRoleBinding
metadata:
  name: prometheus-acm
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: prometheus-acm
subjects:
- kind: ServiceAccount
  name: prometheus-acm
  namespace: monitoring
---
apiVersion: monitoring.coreos.com/v1
kind: Prometheus
metadata:
  name: acm
  namespace: monitoring
  labels:
    prometheus: acm
spec:
  replicas: 2
  serviceAccountName: prometheus-acm
  serviceMonitorSelector:
    matchLabels:
      prometheus: config-management
  podMonitorSelector:
    matchLabels:
      prometheus: config-management
  alerting:
    alertmanagers:
    - namespace: default
      name: alertmanager
      port: web
  resources:
    requests:
      memory: 400Mi
---
apiVersion: v1
kind: Service
metadata:
  name: prometheus-acm
  namespace: monitoring
  labels:
    prometheus: acm
spec:
  type: NodePort
  ports:
  - name: web
    nodePort: 31900
    port: 9190
    protocol: TCP
    targetPort: web
  selector:
    app: prometheus
    prometheus: acm
--- 
  endpoints:
  - port: metrics
    interval: 10s 
---
apiVersion: monitoring.coreos.com/v1
kind: PodMonitor
metadata:
  name: acm-pod
  namespace: monitoring
  labels:
    prometheus: config-management
spec:
  selector:
    matchLabels:
      monitored: "true"
  namespaceSelector:
    matchNames:
    - gatekeeper-system
  podMetricsEndpoints:
  - port: metrics
    interval: 10s

Apply the manifest using the following commands:

kubectl apply -f acm.yaml

until kubectl rollout status statefulset/prometheus-acm -n monitoring; \
do sleep 1; done

The second command blocks until the Pods are running.

You can verify the installation by forwarding the web port of the Prometheus server to your local machine.
```
kubectl -n monitoring port-forward svc/prometheus-acm 9190
```
You can now access the Prometheus web UI at http://localhost:9190.
Remove the temporary directory.
```
cd ..
rm -rf acm-monitor
```

If Policy Controller is enabled on your cluster, you can query the following metrics (all prefixed with gatekeeper_):

Available metrics

Name	Type	Labels	Description
`gatekeeper_audit_duration_seconds`	Histogram		Audit cycle duration distribution
`gatekeeper_audit_last_run_time`	Gauge		The epoch timestamp since the last audit runtime, given as seconds in floating-point
`gatekeeper_constraint_template_ingestion_count`	Counter	status	Total number of constraint template ingestion actions
`gatekeeper_constraint_template_ingestion_duration_seconds`	Histogram	status	Constraint Template ingestion duration distribution
`gatekeeper_constraint_templates`	Gauge	status	Current number of constraint templates
`gatekeeper_constraints`	Gauge	enforcement_action, status	Current number of constraints
`gatekeeper_request_count`	Counter	admission_status	Count of admission requests from the API server
`gatekeeper_request_duration_seconds`	Histogram	admission_status	Admission request duration distribution
`gatekeeper_violations`	Gauge	enforcement_action	Number of audit violations detected in the last audit cycle
`gatekeeper_watch_manager_intended_watch_gvk`	Gauge		How many unique GroupVersionKinds Policy Controller is meant to be watching. This is a combination of synced resources and constraints. Not currently implemented
`gatekeeper_watch_manager_watched_gvk`	Gauge		How many unique GroupVersionKinds Policy Controller is actually watching. This is meant to converge on being equal to gatekeeper_watch_manager_intended_watch_gvk. Not currently implemented
`gatekeeper_sync`	Gauge	kind, status	How many resources have been replicated into OPA's cache
`gatekeeper_sync_duration_seconds`	Histogram		Object sync duration distribution
`gatekeeper_sync_last_run_time`	Gauge		The last time a resource was synced