How to Vendor Tools

In Golang, there are two approaches to working with project dependencies:

Using dependencies from a shared cache of modules or from the project’s vendor directory.
Assuming that dependencies will be available over the network.

In the second approach, the necessary dependencies for building the project are placed inside the project itself.

Vendoring libraries

When using libraries, you first update the list of used dependencies in go.mod, and then create a vendor directory from these dependencies by running:

go mod tidy
go mod vendor

After executing these two commands, all used libraries will be copied into the vendor directory, and Go commands like go ... will look for dependencies there. Only the actually used part of the code is vendored.

Vendoring tools

If your project uses vendor, you might also want to store related tools in a similar way. For example, goimports for formatting imports.

Unfortunately, this process is not straightforward. To create a vendored toolset, create a file called tools.go. You can place it at the root of your project or as a separate package.

Here’s an example:

//go:build tools
// +build tools

package tools

import (
    _ golang.org/x/tools/cmd/goimports
)

The beginning of the file is a build constraint for building tools. By default, this file will not be included in the build. You can use go mod tidy to remove any files named ignore.

Next, specify the paths to the necessary tools in the import section. Make sure to include the path to the main package of each tool.

Finally, run:

go mod tidy
go mod vendor

Nice surprise

In Golang 1.24, there’s a new directive called tools that can be used directly in go.mod. This makes it easier to specify tools and eliminates the need for this workaround.