Mix v1.6.6 Mix View Source
Mix is a build tool that provides tasks for creating, compiling, and testing Elixir projects, managing its dependencies, and more.
Mix.Project
The foundation of Mix is a project. A project can be defined by using
Mix.Project
in a module, usually placed in a file named mix.exs
:
defmodule MyApp.MixProject do
use Mix.Project
def project do
[
app: :my_app,
version: "1.0.0"
]
end
end
See the Mix.Project
module for detailed documentation on Mix projects.
Once the project is defined, a number of default Mix tasks can be run directly from the command line:
mix compile
- compiles the current projectmix test
- runs tests for the given projectmix run
- runs a particular command inside the project
Each task has its own options and sometimes specific configuration
to be defined in the project/0
function. You can use mix help
to list all available tasks and mix help NAME
to show help for
a particular task.
The best way to get started with your first project is by calling
mix new my_project
from the command line.
Mix.Task
Tasks are what make Mix extensible.
Projects can extend Mix behaviour by adding their own tasks. For example, adding the task below inside your project will make it available to everyone that uses your project:
defmodule Mix.Tasks.Hello do
use Mix.Task
def run(_) do
Mix.shell.info "hello"
end
end
The task can now be invoked with mix hello
.
Dependencies
Mix also manages your dependencies and integrates nicely with the Hex package manager.
In order to use dependencies, you need to add a :deps
key
to your project configuration. We often extract the list of dependencies
into its own function:
defmodule MyApp.MixProject do
use Mix.Project
def project do
[
app: :my_app,
version: "1.0.0",
deps: deps()
]
end
defp deps do
[
{:ecto, "~> 2.0"},
{:plug, github: "elixir-lang/plug"}
]
end
end
You can run mix help deps
to learn more about dependencies in Mix.
Environments
Mix supports different environments. Environments allow developers to prepare and organize their project specifically for different scenarios. By default, Mix provides three environments:
:dev
- the default environment:test
- the environmentmix test
runs on:prod
- the environment your dependencies run on
The environment can be changed via the command line by setting
the MIX_ENV
environment variable, for example:
$ MIX_ENV=prod mix run server.exs
Aliases
Aliases are shortcuts or tasks specific to the current project.
In the Mix.Task
section, we have defined a task that would be
available to everyone using our project as a dependency. What if
we wanted the task to only be available for our project? Just
define an alias:
defmodule MyApp.MixProject do
use Mix.Project
def project do
[
app: :my_app,
version: "1.0.0",
aliases: aliases()
]
end
defp aliases do
[
c: "compile",
hello: &hello/1
]
end
defp hello(_) do
Mix.shell.info "Hello world"
end
end
In the example above, we have defined two aliases. One is mix c
which is a shortcut for mix compile
. The other is named
mix hello
, which is the equivalent to the Mix.Tasks.Hello
we have defined in the Mix.Task
section.
Aliases may also be lists, specifying multiple tasks to be run consecutively:
[all: [&hello/1, "deps.get --only #{Mix.env}", "compile"]]
In the example above, we have defined an alias named mix all
,
that prints hello, then fetches dependencies specific to the
current environment and compiles the project.
Arguments given to the alias will be appended to the arguments of the last task in the list, if the last task is a function they will be given as a list of strings to the function.
Finally, aliases can also be used to augment existing tasks.
Let’s suppose you want to augment mix clean
to clean another
directory Mix does not know about:
[clean: ["clean", &clean_extra/1]]
Where &clean_extra/1
would be a function in your mix.exs
with extra cleanup logic.
Note aliases do not show up on mix help
.
Aliases defined in the current project do not affect its dependencies and aliases defined in dependencies are not accessible from the current project.
Environment variables
Several environment variables can be used to modify Mix’s behaviour.
Mix responds to the following variables:
MIX_ARCHIVES
- specifies the directory into which the archives should be installedMIX_DEBUG
- outputs debug information about each task before running itMIX_ENV
- specifies which environment should be used. See EnvironmentsMIX_EXS
- changes the full path to themix.exs
fileMIX_HOME
- path to Mix’s home directory, stores configuration files and scripts used by MixMIX_PATH
- appends extra code pathsMIX_QUIET
- does not print information messages to the terminalMIX_REBAR
- path to rebar command that overrides the one Mix installsMIX_REBAR3
- path to rebar3 command that overrides the one Mix installs
Environment variables that are not meant to hold a value (and act basically as
flags) should be set to either 1
or true
, for example:
$ MIX_DEBUG=1 mix compile
Link to this section Summary
Functions
Returns the default compilers used by Mix
Sets Mix debug mode
Returns true if Mix is in debug mode
Returns the Mix environment
Changes the current Mix environment to env
Raises a Mix error that is nicely formatted
Returns the current shell
Sets the current shell
Link to this section Functions
Returns the default compilers used by Mix.
It can be used in your mix.exs
to prepend or
append new compilers to Mix:
def project do
[compilers: Mix.compilers ++ [:foo, :bar]]
end
Sets Mix debug mode.
Returns true if Mix is in debug mode.
Returns the Mix environment.
This function should not be used at runtime in application code (as opposed to infrastructure and build code like Mix tasks). Mix is a build tool and may not be available after the code is compiled (for example in a release).
To differentiate the program behavior depending on the environment, it is
recommended to use application environment through Application.get_env/3
.
Proper configuration can be set in Mix.Config
files, often per-environment
(see Mix.Config.import_config/1
for more information).
Changes the current Mix environment to env
.
Be careful when invoking this function as any project configuration won’t be reloaded.
This function should not be used at runtime in application code
(see env/0
for more information).
Raises a Mix error that is nicely formatted.
Returns the current shell.
shell/0
can be used as a wrapper for the current shell. It contains
conveniences for requesting information from the user, printing to the shell and so
forth. The Mix shell is swappable (see shell/1
), allowing developers to use
a test shell that simply sends messages to the current process instead of
performing IO (see Mix.Shell.Process
).
By default, this returns Mix.Shell.IO
.
Sets the current shell.
After calling this function, shell
becomes the shell that is returned by
shell/0
.