Configuration

Yetibot can be fully configured either by environment variables, a config EDN file, or both. When both are specified, environment variables take precedence; that is, they override any values set by EDN.

See profiles.sample.clj or config.sample.edn for examples of configuring Yetibot. These are equivalent and both immutable.

Rationale

Yetibot supports both immutable and mutable configuration, for configuring different parts of the system.

It's useful to change the configuration of a system at runtime in certain situations. It would be burdensome to have to login to a system where Yetibot runs, change config and restart Yetibot.

On the other hand, the benefits of immutability are well-known. Explicitly separating out the small amount of mutable config from the majority of immutable config lets us maximize immutability benefits and minimize negative affects of mutability in our system.

NB: In the future we may move all mutable configuration to the database.

Modes

• Immutable config sources include both profiles.clj and environmental variables via environ and loading EDN from a file at config/config.edn (this can be overridden with by specifying a CONFIG_PATH env var)

  Any config specified in an EDN file will be overridden by values provided by environ. Environment config can be explicitly ignored by setting an environment variable YETIBOT_ENV_CONFIG_DISABLED=true.

  Providing config via multiple methods makes it compatible with 12-factor configuration and simple usage in container environments while still retaining the ease of of use of the EDN file option.

  The majority of configurable sub-systems use immutable config as they do not need to change very often. Examples include:

  • Chat adapters
  • Twitter credentials
  • Postgres connection string
  • etc.

• Mutable config source is an EDN file stored at ./config/mutable.edn by default. CONFIG_MUTABLE can optionally be defined to specify a custom location. Yetibot reads and writes to this file at runtime, so it should not be modified by hand while Yetibot is running.

  A much smaller subset of commands need mutable config, e.g.:

  • IRC channels
  • Room settings

Prefixes

All immutable config, regardless of the source can be prefixed with either yb or yetibot. Examples:

edn

{:yetibot {:log {:level "debug"}}}

{:yb {:url "yetibot.com"}}

Profile

{:prod
 {:env
  {:yb-twitter-consumer-key "foo"}}}

Environment

YB_GIPHY_KEY="123"

Merged result

If you decided to configure Yetibot through all available means demonstrated above, the merged config data structure would be:

{:log {:level "debug"}
 :url "yetibot.com"
 :twitter {:consumer {:key "foo"}}
 :giphy {:key "123"}}

Note how environment variables are exploded into nested maps, powered by dec.