Configuration Hot Reloading#

GLAuth supports automatic reloading of its TOML configuration file at runtime, without requiring a service restart. This is controlled by the watchconfig boolean in the top-level config 1.

Enabling#

Set watchconfig = true in your TOML config file 2:

# Enable hot-reload of configuration on changes
watchconfig = true

What Gets Reloaded — and What Doesn't#

Important: Hot reloading does not apply to the [ldap], [ldaps], [backend], or [api] sections 3. Changes to those sections require a full service restart. Sections that are live-reloadable include users, groups, behaviors, and other top-level settings.

How It Works#

startConfigWatcher() is called during service startup 4. It:

1. Exits early if WatchConfig is false, or if the config location is an S3 URL (hot reload is only supported for local files) 5.
2. Creates an fsnotify.Watcher to watch the config file path 6.
3. Runs a goroutine that listens for fsnotify events on the file. It handles three event types 7:
   • Write — file was directly modified
   • Remove — file was deleted (handles editors like vim that use rename/remove atomically)
   • Create — file was recreated (when watching a directory)
4. Coalesces changes with a 1-second ticker to avoid reloading on every partial write 8.
5. On a detected change, calls toml.NewConfig() to re-parse the file, then uses copier.Copy to overwrite the in-process activeConfig pointer in place 9. If parsing fails, the old config is retained 10.
6. Re-watches the file after a Remove event (vim-style atomic saves), once the file reappears 11.

Key Files#

Caveats#

• S3 configs are not supported. The watcher skips if the config path starts with s3:// 5.
• Structural sections are not hot-reloaded. Server listen addresses, TLS certificates, and backend/API settings take effect only on restart 3.
• Parse errors are non-fatal. A bad config file during a reload is logged and the old config is kept active 10.
• activeConfig is mutated in place via copier.Copy, so any running handler holding a reference to the struct will see the updated values immediately 12.