Deploying to Kubernetes with Gitlab

This is a step-by-step instruction on how to automate deployment to your Kubernetes cluster with CI/CD pipelines on Gitlab. Another great article on this topic is available here. The full source code is located here.

Prepare an image

In this example, we will deploy a static page served by Nginx.

• Create html folder with and index.html file with the content of your preference.
• Create Dockerfile

FROM nginx
COPY html /usr/share/nginx/html

• Test your image

docker build -t my-nx .

docker run --rm -p 8080:80 my-nx

Then go to http://localhost:8080/ in your browser.

Create .gitlab-ci.yml file

stages:
  - build
  - deploy
build-docker:
  image: docker:latest  
  stage: build  
  services:
    - docker:dind
  variables:
    CONTAINER_IMAGE: ${DOCKER_REGISTRY_USER}/my-nx:${CI_COMMIT_SHORT_SHA}
  before_script:
    - docker login -u "$DOCKER_REGISTRY_USER" -p "$DOCKER_REGISTRY_PASSWORD"
  script: 
    - docker build -t ${CONTAINER_IMAGE} .
    - docker tag ${CONTAINER_IMAGE} ${CONTAINER_IMAGE}
    - docker push "${CONTAINER_IMAGE}"
deploy:
  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
    - sed -i "s/<VERSION>/${CI_COMMIT_SHORT_SHA}/g" deployment.yaml
    - kubectl apply -f deployment.yaml

Add gitlab service account to k8s cluster

Run the following config file gitlab-service-account.yaml

apiVersion: v1
kind: ServiceAccount
metadata:
  name: gitlab-service-account
---
apiVersion: rbac.authorization.k8s.io/v1beta1
kind: ClusterRoleBinding
metadata:
  name: gitlab-service-account-role-binding
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: cluster-admin
subjects:
  - kind: ServiceAccount
    name: gitlab-service-account
    namespace: default

kubectl apply -f gitlab-service-account.yaml

Set Settings/CI/CD/Variables

• DOCKER_REGISTRY_USER — username in docker registry/dockerhub
• DOCKER_REGISTRY_PASSWORD — docker registry password
• SERVER — k8s API endpoint URL, can be found in ~/.kube/config
• CERTIFICATE_AUTHORITY_DATA — found in ~./kube/config under certificate-authority-data section
• USER_TOKEN — can be obtained using the command kubectl describe secret gitlab-service-account-token-*

Now you can run the pipeline, it should build and push docker image and run the deployment to the k8s cluster.