AWS ECS and ECR deployment via Docker and Gitlab CI

.gitlab-ci.yml

image: docker:latest

variables:
  REPOSITORY_URL: <AWS ACCOUNT ID>.dkr.ecr.eu-central-1.amazonaws.com/<ECS REPOSITORY NAME>
  REGION: eu-central-1
  TASK_DEFINTION_NAME: <TASK DEFINITION NAME>
  CLUSTER_NAME: <CLUSTER NAME>
  SERVICE_NAME: <SERVICE NAME>

services:
- docker:dind

before_script:
  - apk add --no-cache curl jq python py-pip
  - pip install awscli
  - $(aws ecr get-login --no-include-email --region "${REGION}")
  - IMAGE_TAG="$(echo $CI_COMMIT_SHA | head -c 8)"

stages:
  - build
  - deploy

build:
  stage: build
  script:
    - echo "Building image..."
    - docker build -t $REPOSITORY_URL:latest .
    - echo "Tagging image..."
    - docker tag $REPOSITORY_URL:latest $REPOSITORY_URL:$IMAGE_TAG
    - echo "Pushing image..."
    - docker push $REPOSITORY_URL:latest
    - docker push $REPOSITORY_URL:$IMAGE_TAG
  only:
    - master

deploy:
  stage: deploy
  script:
    - echo $REPOSITORY_URL:$IMAGE_TAG
    - TASK_DEFINITION=$(aws ecs describe-task-definition --task-definition "$TASK_DEFINTION_NAME" --region "${REGION}")
    - NEW_CONTAINER_DEFINTIION=$(echo $TASK_DEFINITION | python $CI_PROJECT_DIR/update_task_definition_image.py $REPOSITORY_URL:$IMAGE_TAG)
    - echo "Registering new container definition..."
    - aws ecs register-task-definition --region "${REGION}" --family "${TASK_DEFINTION_NAME}" --container-definitions "${NEW_CONTAINER_DEFINTIION}"
    - echo "Updating the service..."
    - aws ecs update-service --region "${REGION}" --cluster "${CLUSTER_NAME}" --service "${SERVICE_NAME}"  --task-definition "${TASK_DEFINTION_NAME}"
  only:
    - master

update_task_definition_image.py

import sys, json, argparse

parser = argparse.ArgumentParser('Replaces image in the task definition')
parser.add_argument('image_uri', metavar='I', type=str, nargs='+',
                   help='The new image URI')

args = parser.parse_args()

definition = json.load(sys.stdin)['taskDefinition']['containerDefinitions']
definition[0]['image'] = args.image_uri[0]
print json.dumps(definition)