Bridge Configuration Reference

This page collects the bridge configuration surface that already exists in the current server/crank implementation.

HTTP environment variables

Variable	Required	Default	Notes
BRIDGE_BIND_ADDRESS	No	0.0.0.0:$PORT or 0.0.0.0:8080	Explicit bind override
BRIDGE_AUTH_USERNAME	No	unset	Must be paired with BRIDGE_AUTH_PASSWORD
BRIDGE_AUTH_PASSWORD	No	unset	Must be paired with BRIDGE_AUTH_USERNAME
PORT	Cloud Run provided	8080 fallback	Used when BRIDGE_BIND_ADDRESS is not set

Runtime environment variables

Variable	Required when runtime enabled	Default	Notes
BRIDGE_SOURCE_RPC_URL	Yes	—	Source-chain RPC endpoint
BRIDGE_TARGET_RPC_URL	Yes	—	Target-chain RPC endpoint
BRIDGE_SOURCE_CHAIN_ID	Yes	—	Parsed as u16
BRIDGE_TARGET_CHAIN_ID	Yes	—	Parsed as u16
BRIDGE_AUTHORITY_KEYPAIR	Yes	—	Filesystem path to signer keypair
BRIDGE_POLL_INTERVAL_SECS	No	15	Parsed as u64 seconds
BRIDGE_CRANK_MAX_ATTEMPTS	No	3	Parsed as u32; must be at least 1
BRIDGE_CRANK_RETRY_BACKOFF_MS	No	1000	Parsed as u64 milliseconds

Runtime activation behavior

The current server parses bridge runtime configuration as optional. If none of the runtime variables are present, bridge runtime stays disabled. If any of them are present, the required set must be complete or startup fails.

Operator note

This is useful for deployment diagnostics: a partially configured service should fail fast instead of coming up “healthy” but not actually cranking.

Cloud Run notes

The current runbook recommends:

• mount the authority keypair from Secret Manager as a file
• keep PORT out of your manually supplied env file
• use /health for first-response debugging
• use /metrics for dashboarding and alerting

Related pages

• Server and Crank
• Authority / Operator Flow