Deploy your serverless framework aws lambda function from aws code build

buildspec.yaml

version: 0.2

phases:
  install:
    runtime-versions:
      nodejs: 12
    commands:
      - npm install -g serverless
      - npm install
      - printenv

  pre_build:
    commands:
      # checkout the version that are installed for the build process.
      - npm --version
      - sls --version
      - aws --version
      # - npm run migrate   
      - sls deploy --stage stage # "--stage stage" is optional
  build:
    commands:
      - echo Build started on `date`
      - ls
  post_build:
    commands:
      - echo Build completed on `date`
cache:
  paths:
    - node_modules

You might also have to give few policies (permissions) to the code build role so that the serverless can run the cloud formation and s3 uploads.

       "s3:CreateBucket",
        "s3:DeleteBucket",
        "s3:DeleteBucketPolicy",
        "s3:DeleteObject",
        "s3:DeleteObjectVersion",
        "s3:Get*",
        "s3:List*",
        "s3:PutBucketNotification",
        "s3:PutBucketPolicy",
        "s3:PutBucketTagging",
        "s3:PutBucketWebsite",
        "s3:PutEncryptionConfiguration",
        "s3:PutObject"
        "cloudformation:CancelUpdateStack",
        "cloudformation:ContinueUpdateRollback",
        "cloudformation:CreateChangeSet",
        "cloudformation:CreateStack",
        "cloudformation:CreateUploadBucket",
        "cloudformation:DeleteStack",
        "cloudformation:Describe*",
        "cloudformation:EstimateTemplateCost",
        "cloudformation:ExecuteChangeSet",
        "cloudformation:Get*",
        "cloudformation:List*",
        "cloudformation:UpdateStack",
        "cloudformation:UpdateTerminationProtection"