View Source Mix.Config (Mix v1.12.0)
A simple configuration API and functions for managing config files.
This module is deprecated, use the modules Config and Config.Reader
from Elixir's standard library instead.
Setting configuration
Most commonly, this module is used to define your own configuration:
use Mix.Config
config :root_key,
key1: "value1",
key2: "value2"
import_config "#{Mix.env()}.exs"use Mix.Config will import the functions config/2, config/3
and import_config/1 to help you manage your configuration.
Evaluating configuration
Once a configuration is written to a file, the functions in this
module can be used to read and merge said configuration. The eval!/2
function allows you to evaluate a given configuration file and the merge/2
function allows you to deep merge the results of multiple configurations. Those
functions should not be invoked by users writing configurations but
rather by library authors.
Examples
The most common use of Mix.Config is to define application
configuration so that Application.get_env/3 and other Application
functions can be used to retrieve or further change them.
Application config files are typically placed in the config/
directory of your Mix projects. For example, the following config
# config/config.exs
config :my_app, :key, "value"will be automatically loaded by Mix and persisted into the
:my_app's application environment, which can be accessed in
its source code as follows:
"value" = Application.fetch_env!(:my_app, :key1)Link to this section Summary
Functions
Configures the given root_key.
Configures the given key for the given root_key.
Evaluates the given configuration file.
Imports configuration from the given file or files.
Merges two configurations.
Persists the given configuration by modifying the configured applications environment.
Reads the configuration file.
Link to this section Functions
Configures the given root_key.
Keyword lists are always deep merged.
Examples
The given opts are merged into the existing configuration
for the given root_key. Conflicting keys are overridden by the
ones specified in opts. For example, the application
configuration below
config :logger,
level: :warn,
backends: [:console]
config :logger,
level: :info,
truncate: 1024will have a final configuration for :logger of:
[level: :info, backends: [:console], truncate: 1024]Configures the given key for the given root_key.
Keyword lists are always deep merged.
Examples
The given opts are merged into the existing values for key
in the given root_key. Conflicting keys are overridden by the
ones specified in opts. For example, the application
configuration below
config :ecto, Repo,
log_level: :warn,
adapter: Ecto.Adapters.Postgres
config :ecto, Repo,
log_level: :info,
pool_size: 10will have a final value of the configuration for the Repo
key in the :ecto application of:
[log_level: :info, pool_size: 10, adapter: Ecto.Adapters.Postgres]Evaluates the given configuration file.
It accepts a list of imported_paths that should raise if attempted
to be imported again (to avoid recursive imports).
It returns a tuple with the configuration and the imported paths.
Imports configuration from the given file or files.
If path_or_wildcard is a wildcard, then all the files
matching that wildcard will be imported; if no file matches
the wildcard, no errors are raised. If path_or_wildcard is
not a wildcard but a path to a single file, then that file is
imported; in case the file doesn't exist, an error is raised.
If path/wildcard is a relative path/wildcard, it will be expanded relatively to the directory the current configuration file is in.
Examples
This is often used to emulate configuration across environments:
import_config "#{Mix.env()}.exs"Or to import files from children in umbrella projects:
import_config "../apps/*/config/config.exs"Merges two configurations.
The configurations are merged together with the values in the second one having higher preference than the first in case of conflicts. In case both values are set to keyword lists, it deep merges them.
Examples
iex> Mix.Config.merge([app: [k: :v1]], [app: [k: :v2]])
[app: [k: :v2]]
iex> Mix.Config.merge([app: [k: [v1: 1, v2: 2]]], [app: [k: [v2: :a, v3: :b]]])
[app: [k: [v1: 1, v2: :a, v3: :b]]]
iex> Mix.Config.merge([app1: []], [app2: []])
[app1: [], app2: []]Persists the given configuration by modifying the configured applications environment.
config should be a list of {app, app_config} tuples or a
%{app => app_config} map where app are the applications to
be configured and app_config are the configuration (as key-value
pairs) for each of those applications.
Returns the configured applications.
Examples
Mix.Config.persist(logger: [level: :error], my_app: [my_config: 1])
#=> [:logger, :my_app]Reads the configuration file.
The same as eval!/2 but only returns the configuration
in the given file, without returning the imported paths.
It exists for convenience purposes. For example, you could
invoke it inside your mix.exs to read some external data
you decided to move to a configuration file:
subsystem: Mix.Config.read!("rel/subsystem.exs")