CodePipelineActions to run CLI commands without a codebuild project?

[Nikola-Milovic]

Hello everyone, I've found myself several times in a situation where there are some pipelines that just do something without any kind of input that usually run CLI commands. For example clearing the s3 bucket, invalidating cloudfront cache and so on. It seems that I am missing a better alternative since these actions always require an input, and I cannot specify an empty input since it will fail.

  clearS3BucketAction(runOrder?: number) {
    const clearS3Project = new codebuild.PipelineProject(this, 'ClearS3Project', {
      buildSpec: codebuild.BuildSpec.fromObject({
        version: '0.2',
        phases: {
          build: {
            commands: [
              // This command will remove all files from the specified S3 bucket
              'aws s3 rm s3://${WEBSITE_BUCKET_NAME} --recursive',
            ],
          },
        },
      }),
      environmentVariables: {
        WEBSITE_BUCKET_NAME: { value: this.websiteBucket.bucketName },
      },
    });

    const emptyInput = new codepipeline.Artifact();
    const clearS3Action = new codepipeline_actions.CodeBuildAction({
      actionName: 'ClearS3',
      project: clearS3Project,
      input: emptyInput,
      runOrder: runOrder,
    });

    return clearS3Action
  }

The alternative would be something like

  clearS3BucketAction(runOrder?: number) {
    const clearS3Function = new lambda.Function(this, 'ClearS3Function', {
      runtime: lambda.Runtime.NODEJS_14_X,
      code: lambda.Code.fromInline(`
            const AWS = require('aws-sdk');
            const s3 = new AWS.S3();

            exports.handler = async function(event, context) {
                const bucketName = process.env.WEBSITE_BUCKET_NAME;
                const listObjects = await s3.listObjectsV2({ Bucket: bucketName }).promise();

                if (listObjects.Contents.length) {
                    await s3.deleteObjects({
                        Bucket: bucketName,
                        Delete: {
                            Objects: listObjects.Contents.map(({ Key }) => ({ Key }))
                        }
                    }).promise();
                }

                return { statusCode: 200, body: 'Bucket cleared!' };
            };
        `),
      handler: 'index.handler',
      environment: {
        WEBSITE_BUCKET_NAME: this.websiteBucket.bucketName
      }
    });

    // Grant the Lambda function permissions to read and write from the S3 bucket
    this.websiteBucket.grantReadWrite(clearS3Function);

    const lambdaInvokeAction = new codepipeline_actions.LambdaInvokeAction({
      actionName: 'ClearS3',
      lambda: clearS3Function,
      runOrder: runOrder
    });

    return lambdaInvokeAction;
  }

Not much simpler and I have to code the logic myself even though it is supported by CLI. (and I believe the Lambda in this state wouldnt work/ never complete)

Another place where I need something like this

  createInvalidationPipelineAction(runOrder?: number) {
    const invalidateBuildProject = new codebuild.PipelineProject(this, `${this.name}InvalidateCloudFrontCacheProject`, {
      buildSpec: codebuild.BuildSpec.fromObject({
        version: '0.2',
        phases: {
          build: {
            commands: [
              // Choose whatever files or paths you'd like, or all files as specified here
              'aws cloudfront create-invalidation --distribution-id ${CLOUDFRONT_ID} --paths "/*"',
            ],
          },
        },
      }),
      environmentVariables: {
        CLOUDFRONT_ID: { value: this.distribution.distributionId },
      },
    });

    const distributionArn = `arn:aws:cloudfront::${this.account}:distribution/${this.distribution.distributionId}`;
    invalidateBuildProject.addToRolePolicy(new iam.PolicyStatement({
      resources: [distributionArn],
      actions: [
        'cloudfront:CreateInvalidation',
      ],
    }));

    const emptyInput = new codepipeline.Artifact();
    return new codepipeline_actions.CodeBuildAction({
      actionName: `InvalidateCache${this.name}`,
      project: invalidateBuildProject,
      input: emptyInput,
      runOrder: runOrder,
    })
  }