Mix v1.6.6 Mix.Config View Source
Module for defining, reading and merging app configurations.
Most commonly, this module is used to define your own configuration:
use Mix.Config
config :plug,
key1: "value1",
key2: "value2"
import_config "#{Mix.env}.exs"
All config/*
macros, including import_config/1
, are used
to help define such configuration files.
Furthermore, this module provides functions like read!/1
,
merge/2
and friends which help manipulate configurations
in general.
Configuration set using Mix.Config
will set the application env, so
that Application.get_env/3
and other Application
functions can be used
at run or compile time to retrieve or change the configuration.
For example, the :key1
value from application :plug
(see above) can be
retrieved with:
"value1" = Application.fetch_env!(:plug, :key1)
Link to this section Summary
Functions
Configures the given application
Configures the given key for the given application
Imports configuration from the given file or files
Merges two configurations
Persists the given configuration by modifying the configured applications environment
Reads and validates a configuration file
Reads many configuration files given by wildcard into a single config
Validates a configuration
Link to this section Functions
Configures the given application.
Keyword lists are always deep merged.
Examples
The given opts
are merged into the existing configuration
for the given app
. Conflicting keys are overridden by the
ones specified in opts
. For example, the declaration below:
config :lager,
log_level: :warn,
mode: :truncate
config :lager,
log_level: :info,
threshold: 1024
Will have a final configuration of:
[log_level: :info, mode: :truncate, threshold: 1024]
This final configuration can be retrieved at run or compile time:
Application.get_all_env(:lager)
Configures the given key for the given application.
Keyword lists are always deep merged.
Examples
The given opts
are merged into the existing values for key
in the given app
. Conflicting keys are overridden by the
ones specified in opts
. For example, given the two configurations
below:
config :ecto, Repo,
log_level: :warn,
adapter: Ecto.Adapters.Postgres
config :ecto, Repo,
log_level: :info,
pool_size: 10
the final value of the configuration for the Repo
key in the :ecto
application will be:
[log_level: :info, pool_size: 10, adapter: Ecto.Adapters.Postgres]
This final value can be retrieved at runtime or compile time with:
Application.get_env(:ecto, Repo)
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.
This behaviour is analogous to the one for read_wildcard!/1
.
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 configuration of each application is merged together with the values in the second one having higher preference than the first in case of conflicts.
Examples
iex> Mix.Config.merge([app: [k: :v1]], [app: [k: :v2]])
[app: [k: :v2]]
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 and validates a configuration file.
file
is the path to the configuration file to be read. If that file doesn’t
exist or if there’s an error loading it, a Mix.Config.LoadError
exception
will be raised.
loaded_paths
is a list of configuration files that have been previously
read. If file
exists in loaded_paths
, a Mix.Config.LoadError
exception
will be raised.
Reads many configuration files given by wildcard into a single config.
Raises an error if path
is a concrete filename (with no wildcards)
but the corresponding file does not exist; if path
matches no files,
no errors are raised.
loaded_paths
is a list of configuration files that have been previously
read.
Validates a configuration.