Setting up Kubernetes Addons

2023/06/11

See the GitHub repo for this post in kengz/k0s-cluster.

After creating a Kubernetes cluster, we would want to add a set of standard cluster addons using Helm for DevOps:

cert-manager: certificate management
cluster-autoscaler: to dynamically autoscale cluster by adding or reducing nodes.
metrics-server: for monitoring and and HPA (HorizontalPodAutoscaler) to work.
kubernetes-dashboard: basic cluster monitoring (if Lens is not available)
Loki (scalable): to aggregate and index all logs in the cluster, with retention policy; the logs are searchable in Grafana. Additionally:
- promtail to aggregate logs
- Note: Elasticsearch charts (hence ELK) have been deprecated in favor of their licensed ECK; plus Loki is much easier to run and maintain
kube-prometheus-stack: for cluster monitoring with many useful preconfigured cluster Prometheus metrics in Grafana dashboards. Additionally:
- prometheus-adapter for custom metrics API, e.g. for HPA to scale using custom-defined metrics.
- prometheus-pushgateway to push application metrics
- prometheus-blackbox-exporter to probe endpoints for uptime monitoring

Additionally, install Lens for GUI monitoring and access to the cluster. Get a free license to use.

Installations

cert-manager

# cert manager
helm repo add jetstack https://charts.jetstack.io
helm upgrade -i cert-manager jetstack/cert-manager -n cert-manager --create-namespace --version 'v1.12.1' --set installCRDs=true

cluster-autoscaler

Helm chart here. This component has some custom settings dependending on which cloud provider is used, but the main gist is:

helm repo add autoscaler https://kubernetes.github.io/autoscaler
helm upgrade -i cluster-autoscaler autoscaler/cluster-autoscaler -n kube-system

metrics-server

Helm chart here. Some kubernetes providers have this preinstalled, but the gist is:

helm repo add metrics-server https://kubernetes-sigs.github.io/metrics-server/
helm upgrade -i metrics-server metrics-server/metrics-server -n kube-system --version '3.10.0'

kubernetes-dashboard

Manifest here - this installs more reliably than its Helm chart. First, prepare manifest to create a service account for dashboard access:

./cluster/dashboard-admin-user.yaml

apiVersion: v1
kind: ServiceAccount
metadata:
  name: admin-user
  namespace: kubernetes-dashboard
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
  name: admin-user
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: cluster-admin
subjects:
  - kind: ServiceAccount
    name: admin-user
    namespace: kubernetes-dashboard

Then run:

kubectl apply -f https://raw.githubusercontent.com/kubernetes/dashboard/v2.7.0/aio/deploy/recommended.yaml
kubectl apply -f ./cluster/dashboard-admin-user.yaml

Preferably, install Lens for GUI monitoring and access to the cluster (it connects using kubeconfig). Get a free license to use.

Loki

Helm chart here. Loki is a Grafana project for log aggregation - it is scalable (to TBs), cheap, and simple to maintain. The logs will show up in Grafana dashboards - which is a must-have for Kubernetes clusters.

Elasticsearch has archived their Helm charts and moved to a licensed model (ECK), I can no longer recommend it. Also, it is quite bloated and fragile just for log aggregation.

First, prepare the Helm override file to:

configure storage for scalable mode (s3/GCP/Azure etc., or use minio to try first)
configure retention

./cluster/loki-values.yaml

# for loki scalable mode https://grafana.com/docs/loki/latest/fundamentals/architecture/deployment-modes/#simple-scalable-deployment-mode
# need to configure storage https://github.com/grafana/loki/blob/main/production/helm/loki/values.yaml#L253
# or try with minio first
minio:
  enabled: true
loki:
  storage:
    type: s3
    s3:
      s3: null
      endpoint: null
      region: null
      secretAccessKey: null
      accessKeyId: null
      s3ForcePathStyle: false
      insecure: false
  # configure retention https://grafana.com/docs/loki/latest/operations/storage/retention/
  # fields: https://grafana.com/docs/loki/latest/configuration/
  compactor:
    shared_store: filesystem
    retention_enabled: true
  limits_config:
    retention_period: 744h
  auth_enabled: false

We'll also install promtail as log aggregating agent.

Then run:

helm repo add grafana https://grafana.github.io/helm-charts
helm upgrade -i loki grafana/loki -n logging --create-namespace --version '5.6.4' -f ./cluster/loki-values.yaml
helm upgrade -i promtail grafana/promtail -n logging --version '6.11.3'

Grafana dashboard is installed later in kube-prometheus-stack; we will add Loki as a data source to it for log search on Grafana.

kube-prometheus-stack

Helm chart here. This includes kube-state-metrics, node-exporter, and Grafana: they gather kubernetes metrics from all the cluster nodes, and preconfigure many useful cluster metric dashboards.

Prepare the Helm override file to set/change default password, and add Loki as data source for log search in Grafana:

./cluster/prometheus-values.yaml

grafana:
  adminPassword: prom-operator
  # configure anonymous view-access
  grafana.ini:
    auth.anonymous:
      enabled: true
      org_name: Main Org.
      org_role: Viewer
    # auth:
    #   disable_login_form: true

  persistence:
    enabled: true

  ## Configure additional grafana datasources (passed through tpl)
  ## ref: http://docs.grafana.org/administration/provisioning/#datasources
  additionalDataSources:
    - name: Loki
      type: loki
      access: proxy
      url: http://loki-gateway.logging.svc.cluster.local
      version: 1
      isDefault: false

We will also install 3 additional Helm charts. The first is prometheus-adapter for custom metrics API, e.g. for HPA to scale using custom-defined metrics.

The second is Prometheus Pushgateway, e.g. to push application metrics. Specify Helm override file to configure ServiceMonitor with matching label so it is scraped by kube-prometheus-stack:

./cluster/pushgateway-values.yaml

serviceMonitor:
  enabled: true
  additionalLabels:
    release: prometheus

The third is Blackbox Exporter to probe endpoints for uptime monitoring. Specify the Helm override file to configure targets and ServiceMonitor with matching label so it is scraped by kube-prometheus-stack:

./cluster/blackbox-values.yaml

config:
  modules:
    http_2xx:
      prober: http
      timeout: 5s
      http:
        valid_http_versions: ["HTTP/1.1", "HTTP/2.0"]
        follow_redirects: true
        preferred_ip_protocol: "ip4"
        valid_status_codes:
          - 200

serviceMonitor:
  enabled: true
  defaults:
    labels:
      # match kube-prometheus-stack scrape config
      release: prometheus
    interval: 30s
    scrapeTimeout: 30s
    module: http_2xx
  scheme: http

  targets: # lowercase only
    - name: github
      url: http://github.com/status
    - name: gitlab
      url: https://status.gitlab.com

Now, install all of these by running:

helm repo add prometheus-community https://prometheus-community.github.io/helm-charts
helm upgrade -i prometheus prometheus-community/kube-prometheus-stack -n monitoring --create-namespace --version '46.8.0' -f ./cluster/prometheus-values.yaml
# adapter for k8s HPA custom metrics
helm upgrade -i prom-adapter prometheus-community/prometheus-adapter -n monitoring --version '4.2.0'
# pushgateway for app metrics
helm upgrade -i prom-pushgateway prometheus-community/prometheus-pushgateway -n monitoring --version '2.2.0' -f ./cluster/pushgateway-values.yaml
# blackbox exporter for uptime monitoring
helm install blackbox prometheus-community/prometheus-blackbox-exporter -n monitoring --version '7.10.0' -f ./cluster/blackbox-values.yaml

Grafana Dashboards can also be provisioned via ConfigMaps. See the repo linked above for more examples as the ConfigMap file is large.

Accessing Dashboards

After installing the addons, access all the dashboards as follows:

Lens
- just open the app, it will use ~/.kube/config to connect

Kubernetes Dashboard
- get token: kubectl -n kubernetes-dashboard create token admin-user
- run kubectl proxy and visit http://localhost:8001/api/v1/namespaces/kubernetes-dashboard/services/https:kubernetes-dashboard:/proxy/

Grafana for cluster and logging monitoring
- data sources include kube-state-metrics, node-exporter, prometheus, and custom-added loki for logs
- run kubectl port-forward -n monitoring svc/prometheus-grafana 6060:80 and visit http://localhost:6060 to find the preconfigured dashboards
- (one-time) import this Loki Kubernetes Logs and this Blackbox exporter dashboards

Prometheus for cluster monitoring
- run kubectl port-forward -n monitoring svc/prometheus-kube-prometheus-prometheus 9090:9090 and visit http://localhost:9090

See the GitHub repo for this post in kengz/k0s-cluster.

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