Runtime State Files

The BFF writes one runtime state file, managed automatically — it never needs hand-editing.

debugLog.file

Field	Type	Default	Required	Notes
debugLog.file	string	./horizon-wire.jsonl	no	Filesystem path to the OAP wire debug log. Only written when debugLog.enabled is set.

The OAP request/response wire trace, off by default. See Debug Log.

Env-var fallback

When horizon.yaml does not supply debugLog.file, the default is seeded from an env var:

YAML key	Env-var fallback	Default
debugLog.file	HORIZON_WIRE_LOG_FILE	./horizon-wire.jsonl

The published Docker image sets this env var to a /data/... path so an operator who runs the image without a horizon.yaml override gets writes routed to the declared /data volume — see Container Image → Persisting the wire debug log. An explicit value in horizon.yaml always wins over the env-var fallback.

Operational notes

• This is mutable runtime state. It should be on durable storage, not a container tmpfs, if you want it to survive a restart.
• It is gitignored by default (see .gitignore). It is not source-controlled; it is operational state.
• Appends are atomic. The log is append-only, so a crash mid-write cannot corrupt earlier records.
• It is a debugging aid, not a security record. It captures OAP request and response payloads when switched on, and it is off by default because those payloads are large and can carry data you would not want at rest. For a record of who signed in, read the application log; Horizon keeps no record of who changed what.