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SAM Builds in CodePipeline: A buildspec.yml Deep Dive

SAM Builds in CodePipeline: A buildspec.yml Deep Dive

Deep-dive into configuring your SAM application with CodePipeline and CodeBuild using buildspec.yaml, highlighting key configurations for seamless deployments.

📌 Step-by-Step Configuration:

1️⃣ Add a Proper  buildspec.yaml  File

Your CodeBuild project uses a  buildspec.yaml  to run the AWS SAM commands for packaging and deployment:
YAML
version: 0.2
phases:
  pre_build:
    commands:
      - echo Logging in to SAM build...
      - aws --version
      - sam --version
      - mvn --version
  build:
    commands:
      - echo Build started on `date`
      - cd HelloWorldFunction
      - mvn clean compile install -DskipTests=true
      - cd ..
      - sam validate -t template.yaml --lint
      - echo ${S3_BUCKET} # S3_BUCKET defined in the environment variables of the code build
      - sam package --template-file template.yaml --s3-bucket ${S3_BUCKET} --output-template-file packaged.yaml --no-resolve-s3
  post_build:
    commands:
      - echo Build completed on `date`
artifacts:
  files:
    - HelloWorldFunction/target/HelloWorld-1.0.jar
    - packaged.yaml
  • ✅ Note: The packaged SAM template ( packaged.yaml ) is generated from your original  template.yaml . This  packaged.yaml  is referenced explicitly in your pipeline for deployment.


2️⃣ CodePipeline Configuration with CloudFormation Actions

Ensure your AWS CodePipeline explicitly uses the  packaged.yaml  created during the build stage:
YAML
- Name: Deploy
  OnFailure:
    Result: ROLLBACK
  Actions:
    - Name: CreateChangeSet
      ActionTypeId:
        Category: Deploy
        Owner: AWS
        Provider: CloudFormation
        Version: '1'
      InputArtifacts:
        - Name: BuildOutput
      Configuration:
        ActionMode: CHANGE_SET_REPLACE
        StackName: !Sub "${StackName}-${AWS::AccountId}-${AWS::Region}"
        Capabilities: CAPABILITY_IAM,CAPABILITY_AUTO_EXPAND,CAPABILITY_NAMED_IAM
        ChangeSetName: !Sub "CodePipelineChangeSet-${AWS::AccountId}-${AWS::Region}"
        TemplatePath: "BuildOutput::packaged.yaml"
        RoleArn: !GetAtt CodePipelineRole.Arn
      RunOrder: 1

    - Name: ExecuteChangeSet
      ActionTypeId:
        Category: Deploy
        Owner: AWS
        Provider: CloudFormation
        Version: '1'
      InputArtifacts:
        - Name: BuildOutput
      Configuration:
        ActionMode: CHANGE_SET_EXECUTE
        StackName: !Sub "${StackName}-${AWS::AccountId}-${AWS::Region}"
        Capabilities: CAPABILITY_IAM,CAPABILITY_AUTO_EXPAND,CAPABILITY_NAMED_IAM
        ChangeSetName: !Sub "CodePipelineChangeSet-${AWS::AccountId}-${AWS::Region}"
        TemplatePath: "BuildOutput::packaged.yaml"
        RoleArn: !GetAtt CodePipelineRole.Arn
      RunOrder: 2
  • ✅ Note: The  OnFailure: ROLLBACK  ensures that failed deployments automatically roll back to the last known stable configuration.


3️⃣ Configuring AWS CodeBuild with Environment Variables

The AWS CodeBuild environment explicitly specifies the artifact bucket ( S3_BUCKET ) as an environment variable:
YAML
CodeBuildProject:
  Type: AWS::CodeBuild::Project
  Properties:
    Name: CodeBuildMaven
    LogsConfig:
      CloudWatchLogs:
        Status: ENABLED
        GroupName: !Ref CodeBuildLogGroup
    Source:
      Type: CODEPIPELINE
      BuildSpec: "buildspec.yaml"
    Environment:
      ComputeType: BUILD_GENERAL1_SMALL
      Image: "aws/codebuild/amazonlinux-x86_64-standard:5.0"
      Type: LINUX_CONTAINER
      EnvironmentVariables:
        - Name: S3_BUCKET
          Type: PLAINTEXT
          Value: !Ref ArtifactBucketName
    ServiceRole: !GetAtt CodeBuildRole.Arn
    Artifacts:
      Type: CODEPIPELINE
  • ✅ Tip: This setup ensures secure and easy management of environment-specific configurations.


4️⃣ Utilizing Correct Artifact Paths in SAM Templates

Your SAM  template.yaml  should correctly reference the artifact files created during the build:
YAML
HelloWorldFunction:
  Type: AWS::Serverless::Function
  Properties:
    CodeUri: HelloWorldFunction/target/HelloWorld-1.0.jar
    Handler: helloworld.App::handleRequest
    Runtime: java11
    Architectures:
      - x86_64
    MemorySize: 512
    Environment:
      Variables:
        PARAM1: VALUE
        JAVA_TOOL_OPTIONS: -XX:+TieredCompilation -XX:TieredStopAtLevel=1
    Events:
      HelloWorld:
        Type: Api
        Properties:
          Path: /hello
          Method: get
  • ✅ Important: The  CodeUri  path aligns precisely with the artifacts specified in  buildspec.yaml .


🎯 Putting It All Together:

This robust SAM build and deployment setup allows seamless integration into your CI/CD workflow, ensuring consistent, automated deployments and rollbacks.
For a complete walk-through on the AWS CodePipeline automatic rollback integration, refer to my detailed blog:
📖  Implementing AWS CodePipeline Automatic Rollback with SAM & CloudFormation 

🔖 Summary & Key Takeaways:
  • Clearly configure your build and deploy stages with  buildspec.yaml .
  • Use environment variables effectively for secure, maintainable pipelines.
  • Ensure precise artifact referencing to avoid deployment inconsistencies.
  • Automatically roll back to maintain application stability.
Now you're ready to build more resilient, serverless applications with AWS SAM and CodePipeline! 🚀

🎉 About the Author PBKN is a 12x AWS Certified (AWStronaut) & Official AWS SME & Community Builder
Follow on -  https://www.linkedin.com/in/pbkn/   
# aws-sam# codepipeline# codebuild# cicd# java
Any opinions in this article are those of the individual author and may not reflect the opinions of AWS.
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