Mason JETLS Registry

Custom Mason registry for installing JETLS.jl

Prerequisites

• Julia (v1.12.0 or higher)
• Git
• Neovim with Mason installed

Installation

Neovim Configuration

Add the Mason configuration to your Neovim setup. For LazyVim, create or update lua/plugins/mason.lua:

return {
  "mason-org/mason.nvim",
  opts = function(_, opts)
    opts.registries = opts.registries or {
      "github:mason-org/mason-registry",
    }

    -- Add custom JETLS registry
    table.insert(opts.registries, 1, "github:ultimatile/mason-jetls-registry")

    return opts
  end,
}

Install JETLS

Open Neovim and run:

:Mason

Search for jetls and install it using i.

Alternatively, install from command line:

:MasonInstall jetls

How It Works

The registry installs the prebuilt JETLS app via Pkg.Apps:

1. Runs julia --startup-file=no -e 'using Pkg; Pkg.Apps.add(; url="https://github.com/aviatesk/JETLS.jl", rev="<version>")'.
2. Pkg.Apps places the executable in ~/.julia/bin/jetls (or jetls.cmd on Windows).
3. Mason links that executable into its own bin/jetls, so the app can run without a local project checkout.

Mason exposes ~/.local/share/nvim/mason/bin/jetls, which simply forwards to the Pkg.Apps binary under ~/.julia/bin/jetls.

LSP Configuration

After installation, configure the LSP in your Neovim setup. For LazyVim with nvim-lspconfig:

return {
  "neovim/nvim-lspconfig",
  opts = {
    servers = {
      jetls = {
        -- Server-specific settings can be added here
      },
    },
  },
}

Troubleshooting

Julia not found

Make sure Julia is installed and available in your PATH:

which julia
julia --version

Installation fails

Check Mason logs:

:MasonLog

Server doesn't start

Verify the installation:

~/.local/share/nvim/mason/bin/jetls --help

Or check if the wrapper script exists:

ls -la ~/.local/share/nvim/mason/packages/jetls/bin/

Registry Structure

mason-jetls-registry/
├── .github/
│   └── workflows/
│       └── release.yml      # Automated releases via GitHub Actions
├── packages/
│   └── jetls/
│       └── package.yaml     # JETLS package definition
└── README.md

Development

Local Testing

For rapid development and testing, use the file: registry to test changes without pushing to GitHub:

return {
  "mason-org/mason.nvim",
  opts = function(_, opts)
    opts.registries = opts.registries or {
      "github:mason-org/mason-registry",
    }

    -- Use local file registry for development
    table.insert(opts.registries, 1, "file:/path/to/mason-jetls-registry")

    return opts
  end,
}

After making changes to packages/jetls/package.yaml, restart Neovim and reinstall:

:MasonUninstall jetls
:MasonInstall jetls

Package Definition

The package is defined in packages/jetls/package.yaml using:

• Source: pkg:github/aviatesk/JETLS.jl@<version>
• Build Instructions: Platform-specific scripts for Unix and Windows
• Bin: Wrapper script location

Automated Releases

Releases are automatically created via GitHub Actions when packages/jetls/package.yaml is modified. The workflow:

1. Detects changes to package definitions
2. Generates a timestamped tag (e.g., 2026-01-18-adjective-noun)
3. Compiles package.yaml to registry.json
4. Creates a GitHub release with:
   • registry.json
   • registry.json.zip
   • checksums.txt

Note: The release workflow uses mason-org/actions/registry-release, which requires non-merge commits to detect changes. When merging PRs, use Squash and merge instead of regular merge to ensure releases are created correctly.

Manual Release

To trigger a manual release:

gh workflow run release.yml

Or via GitHub UI: Actions → Release → Run workflow

Note: Manual triggers will only create a release if the latest commit is a non-merge commit that modified packages/.

References

• JETLS.jl Repository
• Mason.nvim
• Mason Registry Examples
• Mason Official Registry