HAProxy Config — VS Code Extension

The missing IDE experience for HAProxy. Stop memorizing directive names, guessing valid options, and discovering config errors only when HAProxy refuses to start.

Full language support for .cfg and .conf HAProxy files — with version-aware validation, intelligent autocompletion, and inline documentation right inside VS Code.

Features

Syntax Highlighting

Every token in your HAProxy config gets meaningful color — section headers, directives, ACL names, backend references, IP addresses, ports, and timeouts.

Syntax highlighting

Intelligent Autocompletion

Context-aware suggestions that know which directives are valid in each section. No more guessing whether use_backend belongs in a backend or a frontend.

Filters by section type (frontend, backend, global, etc.)
Respects mode http vs mode tcp — only shows relevant options
Deprecated directives shown with strikethrough
Every suggestion includes signature and documentation

Autocompletion — directive suggestions

Autocompletion — algorithm values

Autocompletion — http-request actions

Version-Aware Validation

Select your HAProxy version and get real-time diagnostics tailored to it. Directives removed in 2.4? Flagged as errors. Options deprecated in 3.0? Flagged as warnings — with the exact migration path.

Errors — unknown directives, wrong section, removed features, syntax issues
Warnings — deprecated directives with upgrade hints
Cross-references — use_backend pointing to an undefined backend

Validation — syntax error

Validation — deprecation warning

Validation — undefined backend reference

Hover Documentation

Hover over any directive for instant reference: signature, description, valid sections, version availability, and a direct link to the HAProxy docs.

Hover — balance algorithms

Hover — http-request

Hover — option httpchk

Hover — stick-table

Hover — timeout

Go-to-Definition

Press F12 (or Ctrl+Click) on any backend name in a use_backend or default_backend directive to jump directly to its definition.

Go-to-definition

Section Folding

Collapse and expand individual HAProxy sections to focus on what matters.

Section folding

Quick Fix — Deprecated Directives

Deprecated directives get a warning with a lightbulb quick fix. One click replaces the directive with the modern equivalent.

Quick fix for deprecated directive

Snippets

Start typing a section name and get a fully-formed boilerplate with tabstops. No more blank-page paralysis.

Prefix	Inserts
`global`	Global block with logging, threads, stats socket
`defaults`	Defaults with all common timeouts
`frontend`	HTTP frontend
`frontend-ssl`	HTTPS frontend with SSL termination
`backend`	HTTP backend with health check
`backend-ssl`	HTTPS backend
`listen`	HAProxy stats listener
`acl`	ACL definition
`use_backend`	Conditional backend routing
`server`	Server line with health check params
`httpchk`	HTTP health check option

Document Formatting

One keypress (Shift+Alt+F) normalizes your entire config: section headers at column 0, directives indented consistently, blank lines cleaned up — without touching your comments or string values.

Multi-Version HAProxy Support

Validate your config against the exact HAProxy version running in production. Switch versions per workspace — no global settings that affect other projects.

Version	Type	Status
3.1	Stable	✅ Latest — default
3.0	Stable	✅ Supported
2.8	LTS	✅ Recommended LTS
2.6	LTS	✅ Supported
2.4	LTS	✅ Supported (EOL 2026)

The status bar shows your active version at all times. Click it to switch instantly.

Installation

From VS Code:

Open the Extensions panel (Ctrl+Shift+X)
Search for HAProxy Config
Click Install

From the command line:

code --install-extension gmm.gmm-haproxy-vscode

The extension activates automatically when you open any .cfg or .conf file named or detected as HAProxy config.

Configuration

All settings are available under File → Preferences → Settings → HAProxy.

Settings panel

Setting	Default	Description
`haproxy.version`	`3.1`	HAProxy version to validate against
`haproxy.validate.enable`	`true`	Enable/disable live validation
`haproxy.completion.enable`	`true`	Enable/disable autocompletion
`haproxy.trace.server`	`off`	LSP trace level (`off` / `messages` / `verbose`)

Per-workspace version — open .vscode/settings.json and add:

{
  "haproxy.version": "2.8"
}

This overrides the global setting for that workspace only, so different projects can validate against different HAProxy versions simultaneously.

Commands

Command	Description
`HAProxy: Select Version`	Change validation version via QuickPick
`HAProxy: Restart Language Server`	Restart if the server gets into a bad state

Why this extension?

HAProxy is one of the most widely deployed load balancers in the world. But editing its config has always been a text-editor experience — no hints, no validation, no documentation. You either memorize the manual or keep a browser tab open.

This extension brings the config editing experience up to the same level as editing code:

Catch errors before deployment — not when HAProxy refuses to reload
Stay on the right version — avoid deploying directives that don't exist in your production binary
Onboard faster — new team members get inline docs without needing to read the full manual
Move faster — snippets and completion eliminate the boilerplate

Requirements

VS Code 1.110.0 or newer
Node.js is not required on the target machine — the language server is bundled

Contributing

Issues and pull requests are welcome at github.com/JuanTorchia/gmm-haproxy-vscode.

To run locally:

git clone https://github.com/JuanTorchia/gmm-haproxy-vscode
cd gmm-haproxy-vscode
npm install --legacy-peer-deps
npm run compile

Then press F5 in VS Code to open an Extension Development Host with the extension loaded.

Before submitting a PR:

npm run lint must pass
npm run compile must pass
npm test must pass

Changelog

See CHANGELOG.md.

HAProxy Config

gmm