[Infrastructure as Code (IaC)] GitLab Runner, Kubernetes executor and kubectl to deploy manifest to Kubernetes (K8S)

Posted on 2021-10-09 Edited on 2023-09-02 In Infrastructure as Code (IaC) , GitLab , GitLab Runner Views: Word count in article: 2.8k Reading time ≈ 3 mins.

GitLab Runner, Kubernetes executor and kubectl to deploy manifest to Kubernetes (K8S)

GitLab Runner is an application that works with GitLab CI/CD to run jobs in a pipeline.

The Kubernetes executor, when used with GitLab CI, connects to the Kubernetes API in the cluster creating a Pod for each GitLab CI Job.

The Kubernetes command-line tool, kubectl, allows you to run commands against Kubernetes clusters. You can use kubectl to deploy applications, inspect and manage cluster resources, and view logs.

Usages

Creating a Deployment

The following is an example of a Deployment. It creates a ReplicaSet to bring up three nginx Pods:

# nginx-deployment.yaml

apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-deployment
  labels:
    app: nginx
spec:
  replicas: 3
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:1.14.2
        ports:
        - containerPort: 80

Convert kubeconfig file to Base64 format as the Variable.

1	$ base64 -w 0 .kube/config

Use kubectl to deploy manifest to Kubernetes (K8S) in .gitlab.ci.yaml.

kubernetes:
  stage: deploy
  image: bitnami/kubectl:1.22-debian-10
  script:
    - echo ${KUBECONFIG_BASE64} | base64 -d > .kube/config
    - KUBECONFIG=.kube/config kubectl apply -f deployments.yml

Waiting for Pod Running

You can use while loop in shell to waiting for Pod status from Pending to Running.

kubernetes:
  stage: deploy
  script:
    # - APP_LABEL="<Your App Label"
    # - echo ${APP_LABEL}
    # - REPLICAS=3
    # - echo ${REPLICAS}
    - while test `KUBECONFIG=.kube/config kubectl get pods -l ${APP_LABEL} -n default | grep Running | wc -l` -ne ${REPLICAS}; do sleep 5; echo "waiting 5s for pods ${APP_LABEL} ready..."; done

FAQs

base64: invalid input

A likely reason for 76 being the default is that Base64 encoding was to provide a way to include binary files in e-mails and Usenet postings which was intended for humans using monitors with 80 characters width. Having a 76-character width as default made that usecase easier.

-w, --wrap=COLS will wrap encoded lines after COLS character (default 76). Use 0 to disable line wrapping.

1	$ base64 -w 0 .kube/config

Variable value is empty

If the variable is marked as protected, please remember to also mark the corresponding branch as protected, otherwise the obtained variable value is empty.