Do I need separate state files for each environment?

Usually, yes — you should keep separate state files per environment.

Why

Terraform state tracks the real infrastructure it manages. If you use the same state for:

• dev
• staging
• prod

…you can accidentally:

• overwrite resources in the wrong environment
• mix outputs and dependencies
• make it hard to promote changes safely
• create security and access-control issues

Common approach

Use a separate state file for each environment, for example:

• dev/terraform.tfstate
• staging/terraform.tfstate
• prod/terraform.tfstate

If you use a remote backend like S3, that often means:

• different state keys per environment
• sometimes different backend buckets/accounts for stronger isolation

When one state might be okay

A single state can work only if:

• it’s a very small setup
• environments are not truly separate
• you intentionally manage everything as one stack

But for most real projects, separate state is the safer and cleaner choice.

Best practice

• Separate state per environment
• Separate variable files or folders per environment
• Separate credentials/access if possible, especially for prod

If you want, I can show you a common Terraform folder structure for dev/staging/prod.