Reuse the same s3 bucket between stages serverless

Question

Our clients are already registered on our development environment and the management is asking for us to create the production environment without loosing any of the already registered user data.

We are trying to deploy the production environment on ap-southeast-2 and our development environment is already on eu-west-1.

I have made the necessary changes for the deployment to happen on these two regions but the problem is that we are creating cognito and s3 buckets using cloudformation template.

We want to use the same s3 buckets and cognito between these two regions but the problem is when I'm deploying to ap-southeast-2 (production) the stack creation fails because s3 bucket already exists.

Is it possible to reuse the same s3 bucket and cognito between regions and stages? I want the serverless framework to check if these resources exists at the region I choose (in this case eu-west-1). We can't create new buckets because we are at the 100 buckets limit!

Here is the code in how we are creating the s3 buckets. We are using serverless framework with nodejs.

Resources:
  AttachmentsBucket:
    Type: AWS::S3::Bucket
    Properties:
      # Set the CORS policy
      CorsConfiguration:
        CorsRules:
          -
            AllowedOrigins:
              - '*'
            AllowedHeaders:
              - '*'
            AllowedMethods:
              - GET
              - PUT
              - POST
              - DELETE
              - HEAD
            MaxAge: 3000

# Print out the name of the bucket that is created
Outputs:
  AttachmentsBucketName:
    Value:
      Ref: AttachmentsBucket

user_248823 · Answer

I want the serverless framework to check if these resources exists at the region I choose

This is not how Infrastructure as a Code (IaC) works. CloudFormation nor terraform for that matter have any build in tools to "check" if a resource exists or not. The IaC perspective is - if its in a template than only the given template/stack can manage that. There is nothing in between, like it may exist or not.

Having said that, there are ways to re-architect and go around that. The most common ways are:

Since the bucket is common resource, it should be deployed separately from the rest of your stacks, and its name should be passed as an input to the dependant stacks.
Develop a custom resource in the form of a lambda function. The function would use AWS SDK to check for the existence of your buckets, and return that info to your stack for further use.

Reuse the same s3 bucket between stages serverless

1 Answers