Configuration Reference

Everything you can set in the configuration file, the environment, or on the command line.

Config file

By default the server looks for config.toml in the working directory. Pass a different path with --config <path>. The file is read once at startup; restart the process after changing it.

Options

Key	Type	Default	Description
`server.host` optional	string	`"127.0.0.1"`	Address to bind. Use `"0.0.0.0"` to accept connections from other machines.
`server.port` optional	integer	`8080`	TCP port to listen on. Must be between 1 and 65535.
`server.workers` optional	integer	CPU count	Number of worker threads handling requests.
`database.url` required	string	none	Connection URL, for example `postgres://user:pass@host/db`.
`database.max_connections` optional	integer	`10`	Upper bound on pooled connections per worker.
`log.level` optional	string	`"info"`	One of `debug`, `info`, `warn`, `error`.
`log.format` optional	string	`"text"`	`"text"` for humans, `"json"` for log aggregators.
`cache.ttl_seconds` optional	integer	`300`	How long responses are cached. Set to `0` to disable caching.

Environment variables

Every key can be overridden with an environment variable. Replace dots with underscores and prefix with APP_, so server.port becomes APP_SERVER_PORT. Values from the environment always win over the file.

Precedence

Settings are resolved in this order, highest first:

Command-line flags
Environment variables
The config file
Built-in defaults

Secrets. Do not commit database.url with a password to version control. Put it in APP_DATABASE_URL instead.

Example

# config.toml
[server]
host = "0.0.0.0"
port = 8080
workers = 4

[database]
url = "postgres://app@db.internal/app"
max_connections = 20

[log]
level = "info"
format = "json"

[cache]
ttl_seconds = 600

Validate a file without starting the server:

$ app config check --config config.toml
config.toml: ok