CodeBuild free how to

This can be specified by expanding the Additional Configuration section underneath Environment when you create a build project in the console. For the Compute option, select 3 GB memory, 2 vCPUs, which is the build.general1.small type. https://docs.aws.amazon.com/codebuild/latest/userguide/build-env-ref-compute-types.html

This can also be specified using CloudFormation like:

Project:
  Type: AWS::CodeBuild::Project
  Properties:
    Environment:
      ComputeType: BUILD_GENERAL1_SMALL

https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-codebuild-project.html