Deployment automation to Kubernetes with Gitlab and Helm

In the previous post, I gave a brief instruction on how to deploy to Kubernetes using kubectl tool. This might be sufficient for a small set of resources but what if there is a need to deploy multiple resources and replace many variables, the script section would become cumbersome. In this article, I’ll introduce using Helm for processing templates of the configuration.

Creating a helm chart

• helm create mynginx
• rm ./mynginx/templates/*
• create ./mynginx/templates/deployment.yaml :

apiVersion: apps/v1
kind: Deployment
metadata:
  name: {{ .Release.Name }}-deployment
  labels:
    app: {{ .Values.app }}
spec:
  replicas: {{ .Values.replicaCount }}
  selector:
    matchLabels:
      app: {{ .Values.app }}
  template:
    metadata:
      labels:
        app: {{ .Values.app }}
    spec:
      containers:
        - name: {{ .Values.app }}
          image: "{{ .Values.image }}:{{ .Values.version }}"
          ports:
            - containerPort: 80
          env:
            - name: ENV
              value: {{ .Values.env }}

• create ./mynginx/templates/NOTES.txt :

Thank you for installing {{ .Chart.Name }}.
Your release is named {{ .Release.Name }}.
To learn more about the release, try:
$ helm status {{ .Release.Name }}
  $ helm get all {{ .Release.Name }}

• create ./mynginx/values.yaml

replicaCount: 1
app: my-nx
image: zjor/my-nx
env: prod

Let’s make it visible that something is changing at runtime when we provide values to the configuration. Change Dockerfile as follows:

FROM nginx
COPY html /usr/share/nginx/html
CMD ["bash", "-c", "echo \"ENV=${ENV}\" && nginx -g \"daemon off;\""]

Change .gitlab-ci.yml to deploy with helm

deploy_with_helm:
  stage: deploy
  image: dtzar/helm-kubectl
  script:
    - kubectl config set-cluster k8s --server="${SERVER}"
    - kubectl config set clusters.k8s.certificate-authority-data ${CERTIFICATE_AUTHORITY_DATA}
    - kubectl config set-credentials gitlab --token="${USER_TOKEN}"
    - kubectl config set-context default --cluster=k8s --user=gitlab
    - kubectl config use-context default
    - helm upgrade --install mynginx-release ./mynginx --set version=${CI_COMMIT_SHORT_SHA}
  only:
    - feature/helm

Apparently kubectl changes the context so that helm can authorize in the cluster.

Full source code