This is an example linter that can be compiled into a plugin for golangci-lint.

Create the Plugin From This Linter

1. Download the source code
2. From the root project directory, run go build -buildmode=plugin plugin/example.go.
3. Copy the generated example.so file into your project or to some other known location of your choosing. ¹

Create a Copy of golangci-lint that Can Run with Plugins

In order to use plugins, you'll need a golangci-lint executable that can run them.

Plugin dependencies defined in the go.mod file MUST have a matching version (or hash) as the same dependency in th golangci-lint binary if the dependency is used in both.

Because of the high probability of this both using the same dependency, it is recommended to use a locally built binary.

To do so:

1. Download golangci-lint source code
2. From the projects root directory, run make build
3. Copy the golangci-lint executable that was created to your path, project, or other location

Configure Your Project for Linting

If you already have a linter plugin available, you can follow these steps to define its usage in a projects .golangci.yml file.

If you're looking for instructions on how to configure your own custom linter, they can be found further down.

1. If the project you want to lint does not have one already, copy the .golangci.yml to the root directory.
2. Adjust the YAML to appropriate linters-settings.custom entries as so:

   linters-settings:
     custom:
       example:
         path: /example.so
         description: The description of the linter
         original-url: github.com/golangci/example-linter
         settings: # Settings are optional.
           one: Foo
           two:
             - name: Bar
           three:
             name: Bar

That is all the configuration that is required to run a custom linter in your project.

Custom linters are enabled by default, but abide by the same rules as other linters.

If the disable all option is specified either on command line or in .golang.yml files linters.disable-all: true, custom linters will be disabled; they can be re-enabled by adding them to the linters.enable list, or providing the enabled option on the command line, golangci-lint run -Eexample.

The configuration inside the settings field of linter have some limitations (there are NOT related to the plugin system itself): we use Viper to handle the configuration but Viper put all the keys in lowercase, and . cannot be used inside a key.

To Create Your Own Plugin

Your linter must provide one or more golang.org/x/tools/go/analysis.Analyzer structs.

Your project should also use go.mod.

All versions of libraries that overlap golangci-lint (including replaced libraries) MUST be set to the same version as golangci-lint. You can see the versions by running go version -m golangci-lint.

You'll also need to create a Go file like plugin/example.go.

This file MUST be in the package main, and MUST define an exposed function called New with the following signature:

func New(conf any) ([]*analysis.Analyzer, error) {
	// ...
}

See plugin/example.go for more info.

To build the plugin, from the root project directory, run:

go build -buildmode=plugin plugin/example.go

This will create a plugin *.so file that can be copied into your project or another well known location for usage in golangci-lint.

Footnotes

1. Alternately, you can use the -o /path/to/location/example.so output flag to have it put it there for you. ↩