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In this guide, we’ll extend our GitLab CI/CD pipeline by adding a docker_push job that uploads your built image to Docker Hub. By the end, you’ll have a fully automated workflow—from unit tests to containerization and Docker pushes.

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1. Existing Pipeline Overview

Here’s the current .gitlab-ci.yml with four jobs: unit_testing, code_coverage, docker_build, and docker_test. We run these on the main branch or any feature/* branch, including merge requests. 
name: Solar System NodeJS Pipeline

rules:
  - if: $CI_COMMIT_BRANCH == 'main' || $CI_COMMIT_BRANCH =~ /^feature/
    when: always
  - if: $CI_MERGE_REQUEST_SOURCE_BRANCH_NAME =~ /^feature/ && $CI_PIPELINE_SOURCE == 'merge_request_event'
    when: always

stages:
  - test
  - containerization

variables:
  DOCKER_USERNAME: siddharth67
  IMAGE_VERSION: $CI_PIPELINE_ID

unit_testing:
  # …

code_coverage:
  # …

docker_build:
  # …

docker_test:
  # …

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2. Adding the docker_push Job

We’ll append a fifth stage, docker_push, under containerization. This job will:
  • Depend on docker_build and docker_test via needs
  • Leverage Docker-in-Docker (dind) for pushing images
  • Load the previously saved artifact
  • Authenticate to Docker Hub using CI/CD variables
  • Push the image tagged with $IMAGE_VERSION
docker_push:
  stage: containerization
  needs:
    - docker_build
    - docker_test
  image: docker:24.0.5
  services:
    - docker:24.0.5-dind
  script:
    # 1. Load the saved Docker image artifact
    - docker load -i image/solar-system-image-$IMAGE_VERSION.tar

    # 2. Authenticate with Docker Hub
    - docker login --username=$DOCKER_USERNAME --password=$DOCKER_PASSWORD

    # 3. Push the image to Docker Hub
    - docker push $DOCKER_USERNAME/solar-system:$IMAGE_VERSION
Ensure your DOCKER_PASSWORD is masked and protected in GitLab. Never hard-code credentials in your .gitlab-ci.yml.

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3. Defining CI/CD Variables

Navigate to Settings → CI/CD → Variables in your GitLab project and add:
Variable NameValueMaskedDescription
DOCKER_USERNAMEsiddharth67NoYour Docker Hub username
DOCKER_PASSWORD<your_password>YesYour Docker Hub password or access token
M_DB_PASSWORD<mongodb_pass>YesMongoDB connection password (if needed)
The image shows a GitLab CI/CD settings page displaying variables, including masked keys like "DOCKER_PASSWORD" and "M_DB_PASSWORD." The sidebar contains navigation options for various settings and features.
You can also set pipeline-level variables via the GitLab API or include them in a protected group for reuse across multiple projects.

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4. Pipeline Visualization

After pushing the updated .gitlab-ci.yml, GitLab will display five jobs in sequence. The docker_push job runs last, once image build and tests complete.
The image shows a GitLab CI/CD pipeline interface for a NodeJS project, displaying the status of various jobs like code coverage, unit testing, and Docker processes.

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5. Sample docker_push Logs

Below is an example of a successful Docker push in your CI logs: 
$ docker load -i image/solar-system-image-123.tar
Loaded image: solar-system:123

$ docker login --username=siddharth67 --password=$DOCKER_PASSWORD
Login Succeeded

$ docker push siddharth67/solar-system:123
The push refers to repository [docker.io/siddharth67/solar-system]
6bb3b914256b: Pushed
27ef56b51525: Pushed
cd949f4c979d: Pushed
f37b283f479c: Pushed
d324172c3753: Pushed
617df26c92eb: Pushed
ec438b31218: Pushed
1159613137: digest: sha256:55191c68759f6b36e12b0d3667c1b629d2947b25b297c7e05aed021971c09df5 size: 1997
Cleaning up project directory and file based variables
Job succeeded
Once the job completes successfully, visit your Docker Hub repository (siddharth67/solar-system) to confirm the newly pushed tags.

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Further Reading

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