An example of create a flutte CICD using gitlabCI

my_flutter_ci_Cd.yml

stages:
    - test
    - build
    - deploy
    - notify

run_test:
    stage: test
    image: cirrusci/flutter:stable
    script:
        - flutter pub get
        - echo "Running unit test..."
        - flutter test

build_android:
    stage: build
    image: cirrusci/flutter:stable
    only:
      - develop
      - staging
      - master
      - merge_requests
    script:
        - echo "Processing branch $CI_COMMIT_REF_NAME"
        - echo "Extracting project version..."
        - source deploy/yaml.sh
        - create_variables pubspec.yaml
        - export PKG_VERSION= $version #Extract from pubspect.yaml
        - echo "Version $PKG_VERSION"
        - echo $PKG_VERSION >> .version #Save the project version to be used in the next job
        - echo "Installing npm modules.."
        - flutter pub get
        - echo "Buildindg APK..."        - 
        - if [ $CI_COMMIT_REF_NAME == "master" ]; then flutter build apk --release; else flutter build apk; fi #Build debug or release version
    artifacts:
        paths:
            - .version
            - android/app/build/outputs/apk/

deploy_android:
    stage: deploy
    only:
      - develop
      - staging
      - master
      - merge_requests    
    image:
        name: amazon/aws-cli
        entrypoint: [""]
    script:
        - echo "Reading project version..."
        - export PKG_VERSION=$(cat .version) #Get version from the artifact file.
        - echo "Uploading to S3..."
        - aws configure set region us-east-1 #Configure region and upload to s3, depending the branch.
        - if [ $CI_COMMIT_REF_NAME == "master" ]; then
            aws s3 cp android/app/build/outputs/apk/release/app-release.apk s3://jupitec-mobile-repository/android/${CI_COMMIT_REF_NAME}/${PKG_VERSION}/flutter/app.apk;
          else
            aws s3 cp android/app/build/outputs/apk/debug/app-debug.apk s3://jupitec-mobile-repository/android/${CI_COMMIT_REF_NAME}/${PKG_VERSION}/flutter/app.apk;
          fi
        - echo "Get download signed URL"
        - export SIGNED_URL=$(aws s3 presign s3://jupitec-mobile-repository/android/${CI_COMMIT_REF_NAME}/${PKG_VERSION}/flutter/app.apk --expires-in 300000)
        - echo $SIGNED_URL
        - echo $SIGNED_URL > .url #Save the signed url in a file to use in the next job.
    artifacts:
        paths:
            - .url

notify_android:
    stage: notify
    only:
      - develop
      - staging
      - master
      - merge_requests
    image:
        name: curlimages/curl
        entrypoint: [""]
    script:
        - echo "Reading download url..."
        - export DOWNLOAD_URL=$(cat .url) #Get download url from file.
        - export PKG_VERSION=$(cat .version) #Get version url from file.
        - echo "Sending to slack..."
        - export MESSAGE="New Flutter APK release available :+1:! - ENV $CI_COMMIT_REF_NAME - version $PKG_VERSION - dowload link $DOWNLOAD_URL"
        - |
          curl -X POST "https://hooks.slack.com/services/xxxx/xxxx/xxxxx" \
            --header "Content-Type: application/json" \
            --data "{\"text\": \"${MESSAGE}\"}"