codeship-services.yml

my-build:
  build:
    image: 1234.dkr.ecr.us-west-2.amazonaws.com/foo
    dockerfile: Dockerfile

awsdockercfg:
  image: codeship/aws-ecr-dockercfg-generator
  add_docker: true
  encrypted_env_file: env.ecr.encrypted
  environment:
    - AWS_REGION=us-west-2

awsdeployment:
  image: codeship/aws-deployment
  encrypted_env_file: env.dev.encrypted
  environment:
    - AWS_DEFAULT_REGION=us-west-2

codeship-steps.yml

# Tag the master branch with 'latest'
- name: Push_Master_Image_Tag_To_ECR
  service: my-build
  tag: master
  type: push
  registry: https://1234.dkr.ecr.us-west-2.amazonaws.com
  image_name:  1234.dkr.ecr.us-west-2.amazonaws.com/foo
  image_tag: latest
  dockercfg_service: awsdockercfg
  
# This forces ECS to use the new image, built from master
- name: Redeploy_Develop_Environment
  service: awsdeployment
  tag: master
  command: aws ecs update-service --cluster $ECS-CLUSTER-NAME --service $ECS-SERVICE-NAME --force-new-deployment
  

Dockerfile

FROM python:3.6.7-slim-stretch

WORKDIR /opt/app

# Resolve dependencies
COPY requirements.txt ./
RUN pip3 install --no-cache -r requirements.txt

# Copy the rest of the app
COPY . /opt/app

# Clean up to save some space
RUN apt-get clean && rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/*

# Start the application
ENTRYPOINT ["python3", "-u", "/opt/app/main.py"]