App Deployment With GitLabCI

DEPLOYING WITH GITLAB-CI

3 min readFeb 7, 2023

Prerequisites

Gitlab account

A little intro…

Connected to the gitlab instance are runners, which are responsible for executing the pipelines. Here, i’m using a self managed gitlab instance. Following the concept of configuration as code, the pipeline will be written in code and hosted in the applications git repository in a yaml file called .gitlab-ci.yaml.

For this article i’m using a docker container for my execution environment, so the jobs will run inside a container, learn more here. The runner is installed on a machine and on that machine gitlab runner creates docker machines to run the jobs.

.gitlab-ci.yaml

The tasks in a CI/CD pipeline such as running tests, building images, deploying to a server are configured as jobs in a .gitlab-ci.yaml file.

variables:
  IMAGE_NAME: seriki/my-app
  IMAGE_TAG: $CI_PIPELINE_ID

stages:
    - test
    - build
    - deploy

test:
  stage: test
  image:
    name: node:11.10.1
  script:
    - cd app
    - npm install
    - npm run test

build_image:
  stage: build
  image: docker:20
  before_script:
    - echo "$CI_REGISTRY_PASS" | docker login -u $CI_REGISTRY_USER --password-stdin
  script:
    - docker build -t $IMAGE_NAME:$IMAGE_TAG .
    - docker push $IMAGE_NAME:$IMAGE_TAG
    - docker image rm $IMAGE_NAME:$IMAGE_TAG

deploy:
  stage: deploy
  image:
    name: alpine/k8s:1.26.0
    entrypoint: [""]
  before_script:
    - cp $KUBE_CA /tmp/ca.crt
    - cp $KUBE_CLIENT_CERT /tmp/client.crt
    - cp $KUBE_CLIENT_KEY /tmp/client.key
    - curl -s "https://raw.githubusercontent.com/kubernetes-sigs/kustomize/master/hack/install_kustomize.sh"  | bash
    - cd k8s
  script:
    - kubectl config get-contexts
    - kubectl get pods
    - kustomize edit set image $IMAGE_NAME=$IMAGE_NAME:$IMAGE_TAG
    - kubectl apply -k .

Stages

The jobs are configured in stages, without stages our jobs will attempt to run at the same time, this is way to tell the pipeline in what order we want the jobs to run.

stages:
    - test
    - build
    - deploy

Test-Job

A job that will run our tests called “test”, inside the job we configure a script where we tell the job what commands to execute, here the script goes into the app directory, installs npm and runs the test.

test:
  stage: test
  image:
    name: node:11.10.1
  script:
    - cd app
    - npm install
    - npm run test

Build-job

before_script is the same as a script, also has the same syntax, but the runner knows to run the before_script before running the script. Here, i’ll need to log into my docker account before building and pushing the image.

build_image:
  stage: build
  image: docker:20
  before_script:
    - echo "$CI_REGISTRY_PASS" | docker login -u $CI_REGISTRY_USER --password-stdin
  script:
    - docker build -t $IMAGE_NAME:$IMAGE_TAG .
    - docker push $IMAGE_NAME:$IMAGE_TAG
    - docker image rm $IMAGE_NAME:$IMAGE_TAG

Deploy-job

The deploy job is going to deploy the application to kubernetes(minikube cluster) as configured in the script.Here, before the main script runs, there’s also a before script, which is going to copy kubernetes certificates to a temporary location. This way, the job has the permission to carry out the task we are instructing it to in the main script.

deploy:
  stage: deploy
  image:
    name: alpine/k8s:1.26.0
    entrypoint: [""]
  before_script:
    - cp $KUBE_CA /tmp/ca.crt
    - cp $KUBE_CLIENT_CERT /tmp/client.crt
    - cp $KUBE_CLIENT_KEY /tmp/client.key
    - curl -s "https://raw.githubusercontent.com/kubernetes-sigs/kustomize/master/hack/install_kustomize.sh"  | bash
    - cd k8s
  script:
    - kubectl config get-contexts
    - kubectl get pods
    - kustomize edit set image $IMAGE_NAME=$IMAGE_NAME:$IMAGE_TAG
    - kubectl apply -k .