Motivation for this change

The NetBird dashboard is a Single Page Application (SPA). Currently, the nixos/netbird-dashboard module configures Nginx without a fallback to index.html.

Because of this, when users attempt to authenticate using an IDP (like Keycloak or PocketID), the IDP redirects back to the dashboard at routes like /auth or /silent-auth. Nginx intercepts these, fails to find a matching file, and returns a 404 instead of letting the SPA handle the routing.

This change updates the default Nginx tryFiles configuration to "$uri $uri/ /index.html", which properly routes these requests to the frontend app.

• Upstream Issue: netbirdio/netbird#4978
• Related Upstream Dashboard PRs: netbirdio/dashboard#398, netbirdio/dashboard#496

I'll run more tests when I can.

Things done

• Built on platform:
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
• Tested, as applicable:
  • NixOS tests in nixos/tests.
  • Package tests at passthru.tests.
  • Tests in lib/tests or pkgs/test for functions and "core" functionality.
• Ran nixpkgs-review on this PR. See nixpkgs-review usage.
• Tested basic functionality of all binary files, usually in ./result/bin/.
• Nixpkgs Release Notes
  • Package update: when the change is major or breaking.
• NixOS Release Notes
  • Module addition: when adding a new NixOS module.
  • Module update: when the change is significant.
• Fits CONTRIBUTING.md, pkgs/README.md, maintainers/README.md and other READMEs.