Reads a config.exs from the data dir when a release boots.

The file lets you configure a beamlet without rebuilding it. It is a plain Elixir config file:

import Config

config :beamlet,
  policies: [
    explorer: [tools: [:eval]]
  ],
  eval: [timeout: 60_000]

It can set any of the keys Beamlet.Config lists. It is read after all other config, so what it says wins.

A change takes a restart. beamlet policies.show reads the file afresh each time it runs, so you can check a change first. A beamlet with no file starts as usual. A file that fails to evaluate stops the boot with the file and line at fault.

The file stands alone: import_config and config_env/0 do not work in it.

In your own release

The standalone server reads the file already. To read it in your own release, add the provider to its config_providers:

releases: [
  my_app: [
    config_providers: [
      {Beamlet.Config.Provider, path: {:system, "BEAMLET_DATA_DIR", "/config.exs"}}
    ]
  ]
]

path takes any path Config.Provider accepts. Point it at the same directory as :data_dir.