ruff/crates/ruff_server/docs/setup/HELIX.md

Helix Setup Guide for ruff server

First, open the language configuration file for Helix. On Linux and macOS, this will be at ~/.config/helix/languages.toml, and on Windows this will be at %AppData%\helix\languages.toml.

Add the language server by adding:

[language-server.ruff]
command = "ruff"
args = ["server", "--preview"]

Then, you'll register the language server as the one to use with Python. If you don't already have a language server registered to use with Python, add this to languages.toml:

[[language]]
name = "python"
language-servers = ["ruff"]

Otherwise, if you already have language-servers defined, you can simply add "ruff" to the list. For example, if you already have pylsp as a language server, you can modify the language entry as follows:

[[language]]
name = "python"
language-servers = ["ruff", "pylsp"]

!NOTE

Multiple language servers for a single language are only supported in Helix version 23.10 and later.

Once you've set up the server, you should see diagnostics in your Python files. Code actions and other LSP features should also be available.

This screenshot is using select=["ALL]" for demonstration purposes.

If you want to, as an example, turn on auto-formatting, add auto-format = true:

[[language]]
name = "python"
language-servers = ["ruff", "pylsp"]
auto-format = true

See the Helix documentation for more settings you can use here.

You can pass settings into ruff server using [language-server.ruff.config.settings]. For example:

[language-server.ruff.config.settings]
lineLength = 80
[language-server.ruff.config.settings.lint]
select = ["E4", "E7"]
preview = false
[language-server.ruff.config.settings.format]
preview = true

By default, Ruff does not log anything to Helix. To enable logging, set the RUFF_TRACE environment variable to either messages or verbose.

[language-server.ruff]
command = "ruff"
args = ["server", "--preview"]
environment = { "RUFF_TRACE" = "messages" }

!NOTE

RUFF_TRACE=verbose does not enable Helix's verbose mode by itself. You'll need to run Helix with -v for verbose logging.

To change the log level for Ruff (which is info by default), use the logLevel setting:

[language-server.ruff]
command = "ruff"
args = ["server", "--preview"]
environment = { "RUFF_TRACE" = "messages" }

[language-server.ruff.config.settings]
logLevel = "debug"

You can also divert Ruff's logs to a separate file with the logFile setting:

[language-server.ruff]
command = "ruff"
args = ["server", "--preview"]
environment = { "RUFF_TRACE" = "messages" }

[language-server.ruff.config.settings]
logLevel = "debug"
logFile = "~/.cache/helix/ruff.log"

The logFile path supports tildes and environment variables.