Bug: sam deploy crashes with special characters in stack name

[bnusunny]

When using special characters in the stack name, sam deploy crashes with a traceback.

@cortex-assistant fix this bug and create a PR

Steps to reproduce

1. Run sam deploy --stack-name "my-stack@v2"
2. Observe crash with botocore.exceptions.ValidationError

Expected behavior

SAM CLI should validate the stack name and show a friendly error message.

Actual behavior

Unhandled exception with full traceback.

[cortex-assistant]

I'll work on a fix for this issue. The stack name should be validated before being passed to CloudFormation to provide a friendly error message instead of an unhandled exception.

[cortex-assistant]

I've submitted a fix in PR #42: #42

Summary of changes:

• Added a DeployInvalidStackNameError exception class in samcli/commands/deploy/exceptions.py
• Added stack name validation at the start of DeployContext.run() that checks against CloudFormation's allowed pattern (^[a-zA-Z][-a-zA-Z0-9]*$) and enforces the 128-character limit
• Invalid stack names now raise a user-friendly error instead of crashing with an unhandled botocore.exceptions.ValidationError

Files changed:

• samcli/commands/deploy/exceptions.py
• samcli/commands/deploy/deploy_context.py
• tests/unit/commands/deploy/test_deploy_context.py

All relevant tests pass ✅

[cortex-assistant]

The bug fix workflow is complete. Here's a summary of what was done:

1. Triaged the issue and labeled it as bug
2. Investigated and fixed the root cause — the stack name was being passed directly to CloudFormation without validation, causing an unhandled botocore.exceptions.ValidationError when special characters like @ were present
3. Implemented the fix across 3 files:
   • Added a new DeployInvalidStackNameError exception for friendly error messaging
   • Added validation in DeployContext.run() checking the stack name against CloudFormation's pattern (^[a-zA-Z][-a-zA-Z0-9]*$) and 128-char limit
   • Added unit tests covering the new validation logic
4. Created PR Fix: validate stack name to prevent crash with special characters #42: Fix: validate stack name to prevent crash with special characters #42 — all tests passing ✅