feat: make default user role configurable via GOTRUE_DB_DEFAULT_ROLE

[nancysangani]

What kind of change does this PR introduce?

Bug fix + feature

What is the current behavior?

Default role for new users is tied to the deprecated GOTRUE_JWT_DEFAULT_GROUP_NAME. If not set, users get an empty role, causing issues on redeployment.
Fixes #2359

What is the new behavior?

New env var GOTRUE_DB_DEFAULT_ROLE lets you configure the default role. Falls back to "authenticated" if not set. GOTRUE_JWT_DEFAULT_GROUP_NAME still works with a deprecation warning.

[Copilot]

Pull request overview

Introduces a new GOTRUE_DB_DEFAULT_ROLE environment variable to configure the default user role, replacing the deprecated GOTRUE_JWT_DEFAULT_GROUP_NAME. Falls back to "authenticated" if neither is set.

Changes:

• Added DefaultRole field to DBConfiguration and fallback logic in ApplyDefaults
• Updated signupNewUser and adminUserCreate to use config.DB.DefaultRole
• Improved deprecation warning for GOTRUE_JWT_DEFAULT_GROUP_NAME

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.

File	Description
internal/conf/configuration.go	New DefaultRole field and fallback logic in ApplyDefaults
internal/api/signup.go	Use config.DB.DefaultRole instead of config.JWT.DefaultGroupName
internal/api/admin.go	Use config.DB.DefaultRole instead of config.JWT.DefaultGroupName
internal/api/api.go	Updated deprecation warning message

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[nancysangani]

/cc @fadymak
/cc @staaldraad

[nancysangani]

/cc @cemalkilic
/cc @fadymak
/cc @staaldraad

[cstockton]

Please see our https://github.com/supabase/auth/blob/master/CONTRIBUTING.md

[nancysangani]

Hi @cstockton! I've addressed the feedback from this PR by adding proper tests and refining the implementation based on the contributing guidelines.
I've opened a new PR here: #2467
Would really appreciate your review. Thanks!

[cstockton]

@nancysangani I would start by opening issues to discuss if these features will be accepted by the team. Some of them would require platform changes on our side that we might not be willing to commit to.