The Prometheus monitoring module: FAQ

How do I collect metrics from applications running outside of the cluster?

1. Configure a Service similar to the one that collects metrics from your application (but do not set the spec.selector parameter).

2. Create Endpoints for this Service and explicitly specify the IP:PORT pairs that your applications use to expose metrics.

   Port names in Endpoints must match those in the Service.

An example

Application metrics are freely available (no TLS involved) at http://10.182.10.5:9114/metrics.

apiVersion: v1
kind: Service
metadata:
  name: my-app
  namespace: my-namespace
  labels:
    prometheus.deckhouse.io/custom-target: my-app
spec:
  ports:
  - name: http-metrics
    port: 9114
---
apiVersion: v1
kind: Endpoints
metadata:
  name: my-app
  namespace: my-namespace
subsets:
  - addresses:
    - ip: 10.182.10.5
    ports:
    - name: http-metrics
      port: 9114

How do I create custom Grafana dashboards?

Custom Grafana dashboards can be added to the project using the Infrastructure as a Code approach. To add your dashboard to Grafana, create the dedicated GrafanaDashboardDefinition Custom Resource in the cluster.

An example:

apiVersion: deckhouse.io/v1
kind: GrafanaDashboardDefinition
metadata:
  name: my-dashboard
spec:
  folder: My folder # The folder where the custom dashboard will be located.
  definition: |
    {
      "annotations": {
        "list": [
          {
            "builtIn": 1,
            "datasource": "-- Grafana --",
            "enable": true,
            "hide": true,
            "iconColor": "rgba(0, 211, 255, 1)",
            "limit": 100,
...

Caution! System dashboards and dashboards added using GrafanaDashboardDefinition cannot be modified via the Grafana interface.

How do I add alerts and/or recording rules?

The CustomPrometheusRules resource allows you to add alerts.

Parameters:

• groups — is the only parameter where you need to define alert groups. The structure of the groups is similar to that of prometheus-operator.

An example:

apiVersion: deckhouse.io/v1
kind: CustomPrometheusRules
metadata:
  name: my-rules
spec:
  groups:
  - name: cluster-state-alert.rules
    rules:
    - alert: CephClusterErrorState
      annotations:
        description: Storage cluster is in error state for more than 10m.
        summary: Storage cluster is in error state
        plk_markup_format: markdown
      expr: |
        ceph_health_status{job="rook-ceph-mgr"} > 1

How do I provision additional Grafana data sources?

The GrafanaAdditionalDatasource allows you to provision additional Grafana data sources.

A detailed description of the resource parameters is available in the Grafana documentation.

See the datasource type in the documentation for the specific datasource.

An example:

apiVersion: deckhouse.io/v1
kind: GrafanaAdditionalDatasource
metadata:
  name: another-prometheus
spec:
  type: prometheus
  access: Proxy
  url: https://another-prometheus.example.com/prometheus
  basicAuth: true
  basicAuthUser: foo
  jsonData:
    timeInterval: 30s
    httpMethod: POST
  secureJsonData:
    basicAuthPassword: bar

How do I enable secure access to metrics?

To enable secure access to metrics, we strongly recommend using kube-rbac-proxy.

An example of collecting metrics securely from an application inside a cluster

Do the following to set up application metrics protection via the kube-rbac-proxy with the subsequent metrics scraping using Prometheus tools:

1. Create a new ServiceAccount with the following permissions:

   ---
   apiVersion: v1
   kind: ServiceAccount
   metadata:
     name: rbac-proxy-test
   ---
   apiVersion: rbac.authorization.k8s.io/v1
   kind: ClusterRoleBinding
   metadata:
     name: rbac-proxy-test
   roleRef:
     apiGroup: rbac.authorization.k8s.io
     kind: ClusterRole
     name: d8:rbac-proxy
   subjects:
   - kind: ServiceAccount
     name: rbac-proxy-test
     namespace: default
   

   The example uses the d8:rbac-proxy built-in Deckhouse ClusterRole.

2. Create a configuration for the kube-rbac-proxy:

   ---
   apiVersion: v1
   kind: ConfigMap
   metadata:
     name: rbac-proxy-config-test
     namespace: rbac-proxy-test
   data:
     config-file.yaml: |+
       authorization:
         resourceAttributes:
           namespace: default
           apiVersion: v1
           resource: services
           subresource: proxy
           name: rbac-proxy-test
   

   Get more information on authorization attributes in the Kubernetes documentation.

3. Create Service and Deployment for your application with the kube-rbac-proxy as a sidecar container:

   ---
   apiVersion: v1
   kind: Service
   metadata:
     name: rbac-proxy-test
     labels:
       prometheus.deckhouse.io/custom-target: rbac-proxy-test
   spec:
     ports:
     - name: https-metrics
       port: 8443
       targetPort: https-metrics
     selector:
       app: rbac-proxy-test
   ---
   apiVersion: apps/v1
   kind: Deployment
   metadata:
     name: rbac-proxy-test
   spec:
     replicas: 1
     selector:
       matchLabels:
         app: rbac-proxy-test
     template:
       metadata:
         labels:
           app: rbac-proxy-test
       spec:
         securityContext:
           runAsUser: 65532
         serviceAccountName: rbac-proxy-test
         containers:
         - name: kube-rbac-proxy
           image: quay.io/brancz/kube-rbac-proxy:v0.14.0
           args:
           - "--secure-listen-address=0.0.0.0:8443"
           - "--upstream=http://127.0.0.1:8081/"
           - "--config-file=/kube-rbac-proxy/config-file.yaml"
           - "--logtostderr=true"
           - "--v=10"
           ports:
           - containerPort: 8443
             name: https-metrics
           volumeMounts:
           - name: config
             mountPath: /kube-rbac-proxy
         - name: prometheus-example-app
           image: quay.io/brancz/prometheus-example-app:v0.1.0
           args:
           - "--bind=127.0.0.1:8081"
         volumes:
         - name: config
           configMap:
             name: rbac-proxy-config-test
   

4. Add the necessary resource permissions to Prometheus:

   ---
   apiVersion: rbac.authorization.k8s.io/v1
   kind: ClusterRole
   metadata:
     name: rbac-proxy-test-client
   rules:
   - apiGroups: [""]
     resources: ["services/proxy"]
     verbs: ["get"]
   ---
   apiVersion: rbac.authorization.k8s.io/v1
   kind: ClusterRoleBinding
   metadata:
     name: rbac-proxy-test-client
   roleRef:
     apiGroup: rbac.authorization.k8s.io
     kind: ClusterRole
     name: rbac-proxy-test-client
   subjects:
   - kind: ServiceAccount
     name: prometheus
     namespace: d8-monitoring
   

After step 4, your application’s metrics should become available in Prometheus.

An example of collecting metrics securely from an application outside a cluster

Suppose there is a server exposed to the Internet on which the node-exporter is running. By default, the node-exporter listens on port 9100 and is available on all interfaces. One needs to ensure access control to the node-exporter so that metrics can be collected securely. Below is an example of how you can set this up.

Requirements:

• There must be network access from the cluster to the kube-rbac-proxy service running on the remote server.
• The remote server must have access to the Kubernetes API server.

Follow these steps:

1. Create a new ServiceAccount with the following permissions:

   ---
   apiVersion: v1
   kind: ServiceAccount
   metadata:
     name: prometheus-external-endpoint-server-01
     namespace: d8-service-accounts
   ---
   apiVersion: rbac.authorization.k8s.io/v1
   kind: ClusterRole
   metadata:
     name: prometheus-external-endpoint
   rules:
   - apiGroups: ["authentication.k8s.io"]
     resources:
     - tokenreviews
     verbs: ["create"]
   - apiGroups: ["authorization.k8s.io"]
     resources:
     - subjectaccessreviews
     verbs: ["create"]
   ---
   apiVersion: rbac.authorization.k8s.io/v1
   kind: ClusterRoleBinding
   metadata:
     name: prometheus-external-endpoint-server-01
   roleRef:
     apiGroup: rbac.authorization.k8s.io
     kind: ClusterRole
     name: prometheus-external-endpoint
   subjects:
   - kind: ServiceAccount
     name: prometheus-external-endpoint-server-01
     namespace: d8-service-accounts
   

2. Generate a kubeconfig file for the created ServiceAccount (refer to the example on how to generate kubeconfig for ServiceAccount).

3. Copy the kubeconfig file to the remote server. You will also have to specify the kubeconfig path in the kube-rbac-proxy settings (our example uses ${PWD}/.kube/config).

4. Configure node-exporter on the remote server to be accessible only on the local interface (i.e., listening on 127.0.0.1:9100).

5. Run kube-rbac-proxy on the remote server:

   docker run --network host -d -v ${PWD}/.kube/config:/config quay.io/brancz/kube-rbac-proxy:v0.14.0 --secure-listen-address=0.0.0.0:8443 \
     --upstream=http://127.0.0.1:9100 --kubeconfig=/config --logtostderr=true --v=10
   

6. Check that port 8443 is accessible at the remote server’s external address.

7. Create Service and Endpoint, specifying the external address of the remote server as <server_ip_address>:

   ---
   apiVersion: v1
   kind: Service
   metadata:
     name: prometheus-external-endpoint-server-01
     labels:
       prometheus.deckhouse.io/custom-target: prometheus-external-endpoint-server-01
   spec:
     ports:
     - name: https-metrics
       port: 8443
   ---
   apiVersion: v1
   kind: Endpoints
   metadata:
     name: prometheus-external-endpoint-server-01
   subsets:
     - addresses:
       - ip: <server_ip_address>
       ports:
       - name: https-metrics
         port: 8443
   

How do I add Alertmanager?

Create a custom resource CustomAlertmanager with type Internal.

Example:

apiVersion: deckhouse.io/v1alpha1
kind: CustomAlertmanager
metadata:
  name: webhook
spec:
  type: Internal
  internal:
    route:
      groupBy: ['job']
      groupWait: 30s
      groupInterval: 5m
      repeatInterval: 12h
      receiver: 'webhook'
    receivers:
    - name: 'webhook'
      webhookConfigs:
      - url: 'http://webhookserver:8080/'

Refer to the description of the CustomAlertmanager custom resource for more information about the parameters.

How do I add an additional Alertmanager?

Create a custom resource CustomAlertmanager with the type External, it can point to Alertmanager through the FQDN or Kubernetes service.

FQDN Alertmanager example:

apiVersion: deckhouse.io/v1alpha1
kind: CustomAlertmanager
metadata:
  name: my-fqdn-alertmanager
spec:
  external:
    address: https://alertmanager.mycompany.com/myprefix
  type: External

Alertmanager with a Kubernetes service:

apiVersion: deckhouse.io/v1alpha1
kind: CustomAlertmanager
metadata:
  name: my-service-alertmanager
spec:
  external:
    service:
      namespace: myns
      name: my-alertmanager
      path: /myprefix/
  type: External

Refer to the description of the CustomAlertmanager Custom Resource for more information about the parameters.

How do I ignore unnecessary alerts in Alertmanager?

The solution comes down to configuring alert routing in the Alertmanager.

You will need to:

1. Create a parameterless receiver.
2. Route unwanted alerts to this receiver.

Below are samples for configuring CustomAlertmanager.

Receive all alerts with labels service: foo|bar|baz:

receivers:
  # The parameterless receiver is similar to "/dev/null".
  - name: blackhole
  # Your valid receiver.
  - name: some-other-receiver
    # ...
route:
  # Default receiver.
  receiver: blackhole
  routes:
    # Child receiver.
    - matchers:
        - matchType: =~
          name: service
          value: ^(foo|bar|baz)$
      receiver: some-other-receiver

Receive all alerts except for DeadMansSwitch:

receivers:
  # The parameterless receiver is similar to "/dev/null".
  - name: blackhole
  # Your valid receiver.
  - name: some-other-receiver
    # ...
route:
  # default receiver
  receiver: some-other-receiver
  routes:
    # Child receiver.
    - matchers:
        - matchType: =
          name: alertname
          value: DeadMansSwitch
      receiver: blackhole

A detailed description of all parameters can be found in the official documentation.

Why can’t different scrape Intervals be set for individual targets?

The Prometheus developer Brian Brazil provides, probably, the most comprehensive answer to this question. In short, different scrapeIntervals are likely to cause the following complications:

• Increasing configuration complexity;
• Problems with writing queries and creating graphs;
• Short intervals are more like profiling an app, and Prometheus isn’t the best tool to do this in most cases.

The most appropriate value for scrapeInterval is in the range of 10-60s.

How do I limit Prometheus resource consumption?

To avoid situations when VPA requests more resources for Prometheus or Longterm Prometheus than those available on the corresponding node, you can explicitly limit VPA using module parameters:

• vpa.longtermMaxCPU
• vpa.longtermMaxMemory
• vpa.maxCPU
• vpa.maxMemory

How do I set up a ServiceMonitor or PodMonitor to work with Prometheus?

Add the prometheus: main label to the PodMonitor or ServiceMonitor. Add the label prometheus.deckhouse.io/monitor-watcher-enabled: "true" to the namespace where the PodMonitor or ServiceMonitor was created.

Example:

---
apiVersion: v1
kind: Namespace
metadata:
  name: frontend
  labels:
    prometheus.deckhouse.io/monitor-watcher-enabled: "true"
---
apiVersion: monitoring.coreos.com/v1
kind: ServiceMonitor
metadata:
  name: example-app
  namespace: frontend
  labels:
    prometheus: main
spec:
  selector:
    matchLabels:
      app: example-app
  endpoints:
    - port: web

How do I set up a Probe to work with Prometheus?

Add the prometheus: main to Probe. Add the label prometheus.deckhouse.io/probe-watcher-enabled: "true" to the namespace where the Probe was created.

Example:

---
apiVersion: v1
kind: Namespace
metadata:
  name: frontend
  labels:
    prometheus.deckhouse.io/probe-watcher-enabled: "true"
---
apiVersion: monitoring.coreos.com/v1
kind: Probe
metadata:
  labels:
    app: prometheus
    component: probes
    prometheus: main
  name: cdn-is-up
  namespace: frontend
spec:
  interval: 30s
  jobName: httpGet
  module: http_2xx
  prober:
    path: /probe
    scheme: http
    url: blackbox-exporter.blackbox-exporter.svc.cluster.local:9115
  targets:
    staticConfig:
      static:
      - https://example.com/status

How do I set up a PrometheusRules to work with Prometheus?

Add the label prometheus.deckhouse.io/rules-watcher-enabled: "true" to the namespace where the PrometheusRules was created.

Example:

---
apiVersion: v1
kind: Namespace
metadata:
  name: frontend
  labels:
    prometheus.deckhouse.io/rules-watcher-enabled: "true"

How to expand disk size

1. To request a larger volume for a PVC, edit the PVC object and specify a larger size in spec.resources.requests.storage field.
   • You can only expand a PVC if its storage class’s allowVolumeExpansion field is set to true.
2. If storage doesn’t support online resize, the message Waiting for user to (re-)start a pod to finish file system resize of volume on node. will appear in the PersistentVolumeClaim status.
3. Restart the Pod to complete the file system resizing.

How to get information about alerts in a cluster?

You can get information about active alerts not only in the Grafana/Prometheus web interface but in the CLI. This can be useful if you only have access to the cluster API server and there is no way to open the Grafana/Prometheus web interface.

Run the following command to get cluster alerts:

kubectl get clusteralerts

Example:

# kubectl get clusteralerts
NAME               ALERT                                      SEVERITY   AGE     LAST RECEIVED   STATUS
086551aeee5b5b24   ExtendedMonitoringDeprecatatedAnnotation   4          3h25m   38s             firing
226d35c886464d6e   ExtendedMonitoringDeprecatatedAnnotation   4          3h25m   38s             firing
235d4efba7df6af4   D8SnapshotControllerPodIsNotReady          8          5d4h    44s             firing
27464763f0aa857c   D8PrometheusOperatorPodIsNotReady          7          5d4h    43s             firing
ab17837fffa5e440   DeadMansSwitch                             4          5d4h    41s             firing

Run the following command to view a specific alert:

kubectl get clusteralerts <ALERT_NAME> -o yaml

Example:

# kubectl get clusteralerts 235d4efba7df6af4 -o yaml
alert:
  description: |
    The recommended course of action:
    1. Retrieve details of the Deployment: `kubectl -n d8-snapshot-controller describe deploy snapshot-controller`
    2. View the status of the Pod and try to figure out why it is not running: `kubectl -n d8-snapshot-controller describe pod -l app=snapshot-controller`
  labels:
    pod: snapshot-controller-75bd776d76-xhb2c
    prometheus: deckhouse
    tier: cluster
  name: D8SnapshotControllerPodIsNotReady
  severityLevel: "8"
  summary: The snapshot-controller Pod is NOT Ready.
apiVersion: deckhouse.io/v1alpha1
kind: ClusterAlert
metadata:
  creationTimestamp: "2023-05-15T14:24:08Z"
  generation: 1
  labels:
    app: prometheus
    heritage: deckhouse
  name: 235d4efba7df6af4
  resourceVersion: "36262598"
  uid: 817f83e4-d01a-4572-8659-0c0a7b6ca9e7
status:
  alertStatus: firing
  lastUpdateTime: "2023-05-15T18:10:09Z"
  startsAt: "2023-05-10T13:43:09Z"

Remember the special alert DeadMansSwitch — its presence in the cluster indicates that Prometheus is working.

How do I add additional endpoints to a scrape config?

Add the label prometheus.deckhouse.io/scrape-configs-watcher-enabled: "true" to the namespace where the ScrapeConfig was created.

Example:

---
apiVersion: v1
kind: Namespace
metadata:
  name: frontend
  labels:
    prometheus.deckhouse.io/scrape-configs-watcher-enabled: "true"

Add the ScrapeConfig with the required label prometheus: main:

apiVersion: monitoring.coreos.com/v1alpha1
kind: ScrapeConfig
metadata:
  name: example-scrape-config
  namespace: frontend
  labels:
    prometheus: main
spec:
  honorLabels: true
  staticConfigs:
    - targets: ['example-app.frontend.svc.{{ .Values.global.discovery.clusterDomain }}.:8080']
  relabelings:
    - regex: endpoint|namespace|pod|service
      action: labeldrop
    - targetLabel: scrape_endpoint
      replacement: main
    - targetLabel: job
      replacement: kube-state-metrics
  metricsPath: '/metrics'