Language Server for Yaml Files
Latest commit 74f640a Sep 12, 2018

Build Status version Coverage Status

YAML Language Server


  1. YAML validation:
    • Detects whether the entire file is valid yaml
  2. Validation:
    • Detects errors such as:
      • Node is not found
      • Node has an invalid key node type
      • Node has an invalid type
      • Node is not a valid child node
    • Detects warnings such as:
      • Node is an additional property of parent
  3. Auto completion:
    • Auto completes on all commands
    • Scalar nodes autocomplete to schema's defaults if they exist
  4. Hover support:
    • Hovering over a node shows description if available
  5. Document outlining:
    • Shows a complete document outline of all nodes in the document

Language Server Settings

The following settings are supported:

  • yaml.format.enable: Enable/disable default YAML formatter
  • yaml.validate: Enable/disable validation feature
  • yaml.schemas: Helps you associate schemas with files in a glob pattern
  • yaml.customTags: Array of custom tags that the parser will validate against. It has two ways to be used. Either an item in the array is a custom tag such as "!Ref" or you can specify the type of the object !Ref should be by doing "!Ref scalar". For example: ["!Ref", "!Some-Tag scalar"]. The type of object can be one of scalar, sequence, mapping, map.
Associating a schema to a glob pattern via yaml.schemas:

When associating a schema it should follow the format below

yaml.schemas: {
    "url": "globPattern",
    "Kubernetes": "globPattern",
    "kedge": "globPattern"


yaml.schemas: {
    "": "/*"


yaml.schemas: {
    "kubernetes": "/myYamlFile.yaml"


yaml.schemas: {
    "kedge": "/myKedgeApp.yaml"


yaml.schemas: {
    "": "/*",
    "kubernetes": "/myYamlFile.yaml"

yaml.schemas extension allows you to specify json schemas that you want to validate against the yaml that you write. Kubernetes and kedge are optional fields. They do not require a url as the language server will provide that. You just need the keywords kubernetes/kedge and a glob pattern.


This repository only contains the server implementation. Here are some known clients consuming this server:

Developer Support

Getting started

  1. Install prerequisites:
  2. Fork and clone this repository
  3. Install the dependencies
    cd yaml-language-server
    $ npm install
  4. Build the language server
    $ npm run compile
  5. The new built server is now location in out/server/src/server.js.
    node (Yaml Language Server Location)/out/server/src/server.js [--stdio]

Connecting to the language server via stdio

We have included the option to connect to the language server via stdio to help with intergrating the language server into different clients.