Yaml language server

Features

• No configuration needed to detect schemas
• Hover: Show description of field
• Code Action: Open documentation in browser
• Code Action: Fill the field under the cursor with zero values
• Diagnostics: Validate yaml syntax
• Diagnostics: Validate against schema

Automatically detected schemas

• Kubernetes Resources. Detected from kind and apiVersion.
• Custom Resource Definitions. Detected from kind and apiVersion.

Installation

go install github.com/slarwise/yamlls@latest

This will install yamlls into $GOPATH/bin or ~/go/bin. Make sure that dir is in your $PATH.

VS Code

TODO. Do you have to write an extension? Can't you just point to a binary?

Helix

In your languages.toml, add

[[language]]
name = "yaml"
language-servers = ["yamlls"]

[language-server.yamlls]
command = "yamlls"
# Optional configuration, if you want to override what json schema store returns for a specific
# filename, define the filename and schema url here. Only works with basenames, i.e. it doesn't
# work for schemas where the file pattern is something like '**/.github/workflows/*.yaml'.
config = { filenameOverrides = { '.prettierrc' = "https://my.schema.for.prettier/schema.json" } }

NeoVim

In your init.lua, or something sourced from there, add

vim.api.nvim_create_autocmd('Filetype', {
    pattern = "yaml",
    callback = function()
        vim.lsp.start({
            name = "yamlls",
            cmd = { "yamlls" },
            root_dir = vim.fs.dirname(vim.fs.find(".git", { upward = true, path = vim.api.nvim_buf_get_name(0) })[1]),
        })
    end
})

Development

To try out changes using helix, you can do:

# Use yamlls in the current directory
export PATH=.:"$PATH"
# Update source code
go build .
hx examples/service.yaml -vvv
# Test things
# Run :log-open inside helix to see helix logs
tail -f ~/Library/Caches/yamlls/log | jq # Follow the logs from yamlls (on a mac)

Potential TODO's

• Completion
  • If kind or apiVersion is given, give completion suggestions for the other
  • Suggest enums from the schema
• Code actions
  • Add all files in the current directory to .resources in a Kustomization file
• Workspace: If there is an kustomization file, connect the resources somehow? And give info if there are things that don't match
• Kustomization: Warn when not all files are included in resources
• Better navigation through documentation. Maybe a file explorer view as an alternative to a flat view?
• Support schemas from https://www.schemastore.org
• Support reading the schema from the start of a document, useful when you cannot determine the schema from the contents or filename. E.g. helm values.
• Show the available enums in the documentation
• Make a code action that mimics all available kubectl <resource> --dry-run=client --output=yaml with the most basic set of flags needed. So that you can insert a Deployment or an Ingress for example, similar to fill. Remove read-only fields like .status and .metadata.creationTimestamp.

Bugs

• Can't get description of anyOf, such as github workflow jobs.something.runs-on

Credits

• The first version of this repo was basically copied from a-h/examplelsp, which is an awesome starting point for understanding how to write a language server!
• Uses json-schema-for-humans to generate documentation, thank you!