Metrics settings

Every setting below is read once at startup and requires a restart to change. Built-in defaults are overridden by nonempty environment values. Unknown FANOUT_ names fail startup; platform-injected service names are tolerated. Custom names use FANOUT_ plus a clear name, adding the area only when it clarifies. Vendor credentials and endpoints keep the vendor’s documented names.

Environment variable	Type	Default
FANOUT_METRICS_PUBLIC	boolean	false
FANOUT_METRICS_TOKEN or FANOUT_METRICS_TOKEN_FILE	string · secret	—

Notes

FANOUT_METRICS_PUBLIC

Allows unauthenticated Prometheus scrapes.

FANOUT_METRICS_TOKEN

Authorizes Prometheus scrapes with a bearer token; optional when using an admin session.

Secrets

Settings marked secret are redacted from Fanout’s startup configuration log. Supply either the value or its _FILE path, never both. File contents lose exactly one trailing newline (LF or CRLF); empty secrets fail startup.