Sample of buildspec.yml for AWS CodeBuild that builds a Docker image from code and push it to ECR to be deployed via CodePipeline

buildspec.yml

# Change the following to your desired values:
#   __ACCOUNT_NUMBER__
#   __ECR_REGION__
#   __ECR_REPOSITORY_NAME__
#   __ECS_CONTAINER_NAME__

version: 0.2
phases:
  install:
    runtime-versions:
      docker: 18
  pre_build:
    commands:
      - echo Logging in to Amazon ECR...
      - aws --version
      - $(aws ecr get-login --region __ECR_REGION__ --no-include-email)
      - REPOSITORY_URI=__ACCOUNT_NUMBER__.dkr.ecr.__ECR_REGION__.amazonaws.com/__ECR_REPOSITORY_NAME__
      - COMMIT_HASH=$(echo $CODEBUILD_RESOLVED_SOURCE_VERSION | cut -c 1-7)
      - IMAGE_TAG=${COMMIT_HASH:=latest}
  build:
    commands:
      - echo Build started on `date`
      - echo Building the Docker image...          
      - docker build -t $REPOSITORY_URI:latest .
      - docker tag $REPOSITORY_URI:latest $REPOSITORY_URI:$IMAGE_TAG
  post_build:
    commands:
      - echo Build completed on `date`
      - echo Pushing the Docker images...
      - docker push $REPOSITORY_URI:latest
      - docker push $REPOSITORY_URI:$IMAGE_TAG
      - echo Writing image definitions file...
      - printf '[{"name”:"__ECS_CONTAINER_NAME__","imageUri":"%s"}]' $REPOSITORY_URI:$IMAGE_TAG > imagedefinitions.json
artifacts:
  files: imagedefinitions.json

@adshrc

$__ECR_REGION__ , $__ACCOUNT_NUMBER__ , $__ECR_REGION__ need to be configured somewhere ?

Yes you can configure them in environment variables in AWS codebuild during creating a new project