Importing Targets

Mage allows you to import targets from another package into the current magefile. This is very useful when you have common targets that you’d like to be able to reuse across many repos.

Imported Package Restrictions

To import targets from another package, that package must not be a main package. i.e. it cannot be package main. This is in contrast to a normal mage package that must be package main. The reason is that the go tool won’t let you import a main package.

In addition, all files will be imported, not just those tagged with the //+build mage build tag. Again, this is a restriction of the go tool. Mage can build only the .go files in the current directory that have the mage build tag, but when importing code from other directories, it’s simply not possible. This means that any exported function (in any file) that matches Mage’s allowed formats will be picked up as a target.

Aliases and defaults in the imported package will be ignored.

Other than these differences, you can write targets in those packages just like a normal magefile.

Two Ways to Import

Importing targets from a package simply requires adding a // mage:import comment on an import statement in your magefile. If there is a name after this tag, the targets will be imported into what is effectively like a namespace.

import (
    // mage:import
    _ "example.com/me/foobar" 
    // mage:import build
    "example.com/me/builder"
)

The first mage import above will add the targets from the foobar package to the root namespace of your current magefile. Thus, if there’s a func Deploy() in foobar, your magefile will now have a deploy target.

The second import above will create a build namespace for the targets in the builder package. Thus, if there’s a func All() in builder, your magefile will now have a build:all target.

Note that you can use imported package targets as dependencies with mg.Deps, just like any other function works in mg.Deps, so you could have mg.Deps(builder.All).

If you don’t need to actually use the package in your root magefile, simply make the import an underscore import like the first import above.