How to reuse an AWS S3 bucket for multiple Serverless Framework deployments

Credit: Eduardo Rabelo

When using Serverless Framework, the default behaviour is the creation of a S3 bucket for each serverless.yml file, since they are treated as separated projects.

As described in the documentation, when you run serverless deploy we have the following steps happening:

1. An AWS CloudFormation template is created from your serverless.yml.
2. If a Stack has not yet been created, then it is created with no resources except for an S3 Bucket, which will store zip files of your Function code.
3. The code of your Functions is then packaged into zip files.
4. Serverless fetches the hashes for all files of the previous deployment (if any) and compares them against the hashes of the local files.
5. Serverless terminates the deployment process if all file hashes are the same.
6. Zip files of your Functions’ code are uploaded to your Code S3 Bucket.
7. Any IAM Roles, Functions, Events and Resources are added to the AWS CloudFormation template.
8. The CloudFormation Stack is updated with the new CloudFormation template.
9. Each deployment publishes a new version for each function in your service.