Configuration Reference

Reference: the complete key table.

Resolution

1. -Dkey=value command-line overrides (and programmatic appConfig().set) — checked first on every read, the engines' f:setConfig analog.
2. The configuration file: resources/application.yml | .yaml | .properties, in the working directory or next to the application file, or --config <path>.
3. ${ENV_VAR:default} substitution inside values: environment first, then a base configuration key of that name, then the default.

Well-known keys (shared with the engines)

Key	Meaning	Default
application.name	application identity in logs, /info and /health	application
rest.server.port	Event API + actuator port	8085
log.format	text, json (pretty-printed) or compact (single-line JSONL)	text
log.level	log level; the LOG_LEVEL environment variable wins	INFO
info.app.version	version reported by /info	package version
info.app.description	description reported by /info	application.name
show.env.variables	opt-in list of environment variables shown by /env	(empty)
show.application.properties	opt-in list of configuration keys shown by /env	(empty)
mandatory.health.dependencies	routes of health check functions that decide /health	(empty)
optional.health.dependencies	health check routes reported but never affecting status	(empty)

List-valued keys accept a comma/space-separated string (engine syntax) or a YAML list.

Programmatic access

import { appConfig } from 'mercury-composable';

const config = appConfig();
const port = config.get('rest.server.port', 8085);
const name = config.getProperty('application.name', 'application');
config.set('feature.flag', 'on');    // runtime override, checked first