Migrating to Import Linter¶

If you would like to migrate from Layer Linter to Import Linter, you can easily migrate your setup.

Step One - Install¶

pip install import-linter

Step Two - Configure¶

Import Linter uses INI instead of YAML to define its contracts. Create an .importlinter file in the same directory as your layers.yml. This is where your configuration will live.

Converting the format is simple.

Example layers.yml:

Contract one:
    containers:
        - mypackage
    layers:
        - api
        - utils

Contract two:
    # This is a comment.
    containers:
        - mypackage.foo
        - mypackage.bar
        - mypackage.baz
    layers:
        - top
        - middle
        - bottom
    whitelisted_paths:
        - mypackage.foo.bottom.alpha <- mypackage.foo.middle.beta

Equivalent .importlinter:

[importlinter]
root_package = mypackage


[importlinter:contract:1]
name = Contract one
type = layers
containers=
    mypackage
layers=
    api
    utils


[importlinter:contract:2]
# This is a comment.
name = Contract two
type = layers
containers=
    mypackage.foo
    mypackage.bar
    mypackage.baz
layers=
    top
    middle
    bottom
ignore_imports=
    mypackage.foo.bottom.alpha -> mypackage.foo.middle.beta

Things to note:

Import Linter requires the root package to be configured in the file, rather than passed to the command line.
Each contract requires a type - this is because Import Linter supports other contract types.
Each contract needs an arbitrary unique identifier in the INI section (in this case, 1 and 2).
‘Whitelisted paths’ has have been renamed to ‘ignore imports’. The notation is similar except the arrow is reversed; the importing package is still listed first, the imported package second.

Step Three - Run¶

To lint your package, run:

lint-imports

Or, if your configuration file is in a different directory:

lint-imports --config=path/to/.importlinter

Key differences between the packages¶

You may notice slight differences in the imports Import Linter picks up on. The main example is that it does not ignore modules in migrations subpackages, while Layer Linter does.
Import Linter allows you to use other contract types and even define your own.
Import Linter allows you to analyse imports of external packages too (though these don’t make sense in the context of a layers contract).

Further reading can be found in the Import Linter documentation.