Gopls Language Server setup for Go Projects

Enkya

Enkya

December 13, 2019

3 min read

Bruce Bigirwenkya Symbols by Bruce Bigirwenkya on Unsplash

What is a Language Server?

It is a server set up to utilise the language server protocol in order to provide tooling support for your editor.

In the case of Golang, there are 2 language servers at the moment.
One by the sourcegraph team called go-langserver. This is no longer under active maintenance.
The other by the go team called gopls. We shall focus on setting this up since it has support for the latest go projects using go modules.

What is the Language Server Protocol(LSP)

LSP defines the protocol used between an editor or IDE and a language server that provides language features like auto complete, go to definition, …

Why use a Language Server

LSP was developed to reduce implementation overhead, with different editors requiring engineering effort to develop tooling for them. Any update to the tooling specifications meant multiple updates across different tools.

LSP allows for effort to be focused on the Language Server with only a need to build clients for editors to utilise the Language Server for tooling support.

Language Servers promote the idea of supporting your development from the cloud. This means a couple of things

  • No complicated setup for tooling in your local environment. Just set up the language server and it should handle the rest of the tooling needed to support you.
    For example, vscode-go typically requires installing multiple packages like gocode, gopkg, gosymbols, go-outline, … These are all replaced by gopls
  • It is easy to keep up with updated best practices. Utilising one standard language server which receives all updates and can be used to check different projects

How to set up gopls for VS Code

VS Code has an extension called vscode-go to provide rich language support for go projects.

  • Install vscode-go extension in VS Code
  • Opening a go project with support for go modules, vscode-go will prompt you about gopls
  • If you choose to opt in for it, VS Code should handle the rest of the installation of gopls and will set the useLanguageServer setting to true.
    You should be able to use the tooling after reloading the editor.

In order to set it up yourself

  • Install gopls go get golang.org/x/tools/gopls@latest
  • Open up your go project workspace. Ensure it is not running within the go path. Go to the workspace settings and set the useLanguageServer option true.
  • Reload VS Code and you should be good to use the language server for tooling support

Note

  • gopls is in alpha at the time of this writing aiming for a stable release in the first half of 2020
  • vscode-go allows you to set go.toolsGopath to a custom path. If this is not set, It will default to the GOPATH env path

References