gitlab-CI file to build the Docker image and pushes to ECR

gitlab-ci.yml

image: "python:3.6"                         # base dockerimage on which the stages will run. Can be different for each stage.

stages:                                     # each stage runs on a new Docker image. data is not persisted between stages by default.
  - publish_image                           # build docker image and push to registry

build and push docker image:        
  stage: publish_image
  only:                                    # only runs the step when git tag is done and it matches one of the mentioned regex patterns 
    variables:
        - $CI_COMMIT_TAG =~ /^v[0-9]+\.[0-9]+\.[0-9]+-[0-9]+\.[0-9]+\.[0-9]+$/ 
        - $CI_COMMIT_TAG =~ /^v[0-9]+\.[0-9]+\.[0-9]+$/     
  variables:
    DOCKER_REGISTRY: <your-ecr-address>.amazonaws.com                                           # your ECR registry address
    AWS_DEFAULT_REGION: ap-south-1                                                                #region of your ECR repository
    APP_NAME: myapp                                                                               #your repo name for the image
    DOCKER_HOST: tcp://docker:2375
  image: 
    name: amazon/aws-cli
    entrypoint: [""]
  services:
    - docker:dind 
  before_script:
    - echo "$CI_COMMIT_TAG"
    - amazon-linux-extras install docker
    - docker login -u "$CI_REGISTRY_USER" -p "$CI_REGISTRY_PASSWORD" $CI_REGISTRY
  script:
    - docker build -t $DOCKER_REGISTRY/$APP_NAME:$DOCKER_TAG .
    - aws ecr get-login-password | docker login --username AWS --password-stdin $DOCKER_REGISTRY 
    - docker push $DOCKER_REGISTRY/$APP_NAME:$CI_COMMIT_TAG
    - docker push $DOCKER_REGISTRY/$APP_NAME:$DOCKER_TAG