Write to samconfig.toml sooner

[ljacobsson]

Describe your idea/feature/enhancement

Currently when using sam deploy --guided and the final steps fail for various reasons, the samconfig.toml file won't get written to.

This is really annoying, especially for stacks with parameters.

Here's an example of me running sam deploy --guided with an expired SSO token. At the end of it I had no samconfig.toml-file and had to restart from the beginning.

$ sam deploy --guided

Configuring SAM deploy
======================

        Looking for config file [samconfig.toml] :  Not found

        Setting default arguments for 'sam deploy'
        =========================================
        Stack Name [sam-app]: sam-typescript-test
        AWS Region [eu-west-1]: 
        #Shows you resources changes to be deployed and require a 'Y' to initiate deploy
        Confirm changes before deploy [y/N]: 
        #SAM needs permission to be able to create roles to connect to the resources in your template
        Allow SAM CLI IAM role creation [Y/n]: 
        #Preserves the state of previously provisioned resources when an operation fails
        Disable rollback [y/N]: 
        HelloWorldFunction may not have authorization defined, Is this okay? [y/N]: y
        Save arguments to configuration file [Y/n]: 
        SAM configuration file [samconfig.toml]: 
        SAM configuration environment [default]: 

        Looking for resources needed for deployment:
Traceback (most recent call last):
  File "botocore/credentials.py", line 2044, in _get_credentials
  File "botocore/client.py", line 388, in _api_call
  File "botocore/client.py", line 708, in _make_api_call
botocore.errorfactory.UnauthorizedException: An error occurred (UnauthorizedException) when calling the GetRoleCredentials operation: Session token not found or invalid

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "samcli/__main__.py", line 12, in <module>
  File "click/core.py", line 829, in __call__
  File "click/core.py", line 782, in main
  File "click/core.py", line 1259, in invoke
  File "click/core.py", line 1066, in invoke
  File "click/core.py", line 610, in invoke
  File "samcli/lib/cli_validation/image_repository_validation.py", line 92, in wrapped
  File "click/decorators.py", line 73, in new_func
  File "click/core.py", line 610, in invoke
  File "samcli/lib/telemetry/metric.py", line 166, in wrapped
  File "samcli/lib/telemetry/metric.py", line 124, in wrapped
  File "samcli/lib/utils/version_checker.py", line 41, in wrapped
  File "samcli/cli/main.py", line 87, in wrapper
  File "samcli/commands/_utils/cdk_support_decorators.py", line 38, in wrapped
  File "samcli/commands/deploy/command.py", line 193, in cli
  File "samcli/commands/deploy/command.py", line 255, in do_cli
  File "samcli/commands/deploy/guided_context.py", line 559, in run
  File "samcli/commands/deploy/guided_context.py", line 181, in guided_prompts
  File "samcli/lib/bootstrap/bootstrap.py", line 23, in manage_stack
  File "samcli/lib/utils/managed_cloudformation_stack.py", line 86, in manage_stack
  File "samcli/lib/utils/managed_cloudformation_stack.py", line 97, in _create_or_get_stack
  File "botocore/client.py", line 388, in _api_call
  File "botocore/client.py", line 695, in _make_api_call
  File "botocore/client.py", line 714, in _make_request
  File "botocore/endpoint.py", line 102, in make_request
  File "botocore/endpoint.py", line 132, in _send_request
  File "botocore/endpoint.py", line 116, in create_request
  File "botocore/hooks.py", line 357, in emit
  File "botocore/hooks.py", line 228, in emit
  File "botocore/hooks.py", line 211, in _emit
  File "botocore/signers.py", line 93, in handler
  File "botocore/signers.py", line 157, in sign
  File "botocore/signers.py", line 237, in get_auth_instance
  File "botocore/credentials.py", line 620, in get_frozen_credentials
  File "botocore/credentials.py", line 515, in _refresh
  File "botocore/credentials.py", line 531, in _protected_refresh
  File "botocore/credentials.py", line 672, in fetch_credentials
  File "botocore/credentials.py", line 682, in _get_cached_credentials
  File "botocore/credentials.py", line 2046, in _get_credentials
botocore.exceptions.UnauthorizedSSOTokenError: The SSO session associated with this profile has expired or is otherwise invalid. To refresh this SSO session run aws sso login with the corresponding profile.
[159342] Failed to execute script __main__

Proposal

Write to the file as values are entered

[mingkun2020]

Thanks for the feature request! We have a roadmap here, but we also try to take in popular feature requests based on 👍🏽 from the community. We will be adding this to our intake for prioritization.

[qingchm]

@ljacobsson I believe the main drive of us not saving it before executing deployments is that if there was a working set of config, if the applied new config set broke the deployment and override the file, the working version would be lost during development, I do feel the intention here though, so maybe not changing the default behaviour and having an additional --force-save-config sort of flag to be added would be a solution. Let me know how you feel about this approach! Again I will use my try to rationalize the request with the team to see if this additional flag makes sense. If the team agrees on having this supported, will mark this as a good first issue for developer to pick up!