docker-easy-haproxy/docs/plugins.md

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Using Plugins

EasyHAProxy supports a plugin system that extends HAProxy configuration with custom functionality. This guide explains how to use and configure plugins.

What are Plugins?

Plugins automatically run during the discovery cycle and can:

• Add HAProxy configuration directives
• Perform maintenance tasks
• Modify discovery data
• Integrate with external services

Plugin Types

Global Plugins

Execute once per discovery cycle regardless of how many domains are discovered.

Use cases:

• Cleanup tasks
• Global monitoring
• DNS updates
• Log management

Example: cleanup plugin

Domain Plugins

Execute once for each discovered domain/host.

Use cases:

• Domain-specific configuration
• IP restoration (Cloudflare)
• Path blocking
• Custom headers per domain

Examples: cloudflare, deny_pages

Built-in Plugins

Cloudflare Plugin (Domain)

Restores the original visitor IP address when requests come through Cloudflare's CDN.

Why use it: Cloudflare replaces the visitor's IP with its own. This plugin restores the original IP from the CF-Connecting-IP header.

Configuration options:

• enabled - Enable/disable plugin (default: true)
• ip_list_path - Path to Cloudflare IP list (default: /etc/haproxy/cloudflare_ips.lst)

Enable via container label:

services:
  myapp:
    labels:
      easyhaproxy.http.host: example.com
      easyhaproxy.http.plugins: cloudflare

Custom IP list path:

labels:
  easyhaproxy.http.plugins: cloudflare
  easyhaproxy.http.plugin.cloudflare.ip_list_path: /custom/path/cf_ips.lst

HAProxy config generated:

# Cloudflare - Restore original visitor IP
acl from_cloudflare src -f /etc/haproxy/cloudflare_ips.lst
http-request set-header X-Forwarded-For %[req.hdr(CF-Connecting-IP)] if from_cloudflare

Required: Download Cloudflare IP list from Cloudflare documentation.

Cleanup Plugin (Global)

Performs cleanup tasks during each discovery cycle, such as removing old temporary files.

Why use it: Prevents disk space issues by automatically cleaning up temporary files created by EasyHAProxy.

Configuration options:

• enabled - Enable/disable plugin (default: true)
• max_idle_time - Maximum age in seconds before deleting files (default: 300)
• cleanup_temp_files - Enable temp file cleanup (default: true)

Enable via YAML:

# /etc/haproxy/static/config.yaml
plugins:
  enabled: [cleanup]
  config:
    cleanup:
      max_idle_time: 600
      cleanup_temp_files: true

Enable via environment variable:

EASYHAPROXY_PLUGINS_ENABLED=cleanup
EASYHAPROXY_PLUGIN_CLEANUP_MAX_IDLE_TIME=600

Deny Pages Plugin (Domain)

Blocks access to specific paths for a domain, returning a configurable HTTP status code.

Why use it: Protect admin panels, internal APIs, or debugging endpoints from public access.

Configuration options:

• enabled - Enable/disable plugin (default: true)
• paths - Comma-separated list of paths to block (e.g., /admin,/private)
• status_code - HTTP status code to return (default: 403)

Enable via container label:

services:
  webapp:
    labels:
      easyhaproxy.http.host: example.com
      easyhaproxy.http.plugins: deny_pages
      easyhaproxy.http.plugin.deny_pages.paths: /admin,/private,/debug
      easyhaproxy.http.plugin.deny_pages.status_code: 404

HAProxy config generated:

# Deny Pages - Block specific paths
acl denied_path path_beg /admin /private /debug
http-request deny deny_status 404 if denied_path

IP Whitelist Plugin (Domain)

Restricts access to a domain to only specific IP addresses or CIDR ranges.

Why use it: Restrict access to internal tools, admin panels, or staging environments to only trusted IP addresses.

Configuration options:

• enabled - Enable/disable plugin (default: true)
• allowed_ips - Comma-separated list of IPs/CIDR ranges to allow (e.g., 192.168.1.0/24,10.0.0.1)
• status_code - HTTP status code to return for blocked IPs (default: 403)

Enable via container label:

services:
  admin:
    labels:
      easyhaproxy.http.host: admin.example.com
      easyhaproxy.http.plugins: ip_whitelist
      easyhaproxy.http.plugin.ip_whitelist.allowed_ips: 192.168.1.0/24,10.0.0.5
      easyhaproxy.http.plugin.ip_whitelist.status_code: 403

HAProxy config generated:

# IP Whitelist - Only allow specific IPs
acl whitelisted_ip src 192.168.1.0/24 10.0.0.5
http-request deny deny_status 403 if !whitelisted_ip

Important: This blocks ALL IPs except those in the whitelist. Make sure to include your own IP!

JWT Validator Plugin (Domain)

Validates JWT (JSON Web Token) authentication tokens using HAProxy's built-in JWT functionality.

Why use it: Protect APIs and services with JWT authentication without needing application-level code.

Configuration options:

• enabled - Enable/disable plugin (default: true)
• algorithm - JWT signing algorithm (default: RS256)
• issuer - Expected JWT issuer (optional, set to none/null to skip validation)
• audience - Expected JWT audience (optional, set to none/null to skip validation)
• pubkey_path - Path to public key file (required if pubkey not provided)
• pubkey - Public key content as string (required if pubkey_path not provided)

Enable via container label:

services:
  api:
    labels:
      easyhaproxy.http.host: api.example.com
      easyhaproxy.http.plugins: jwt_validator
      easyhaproxy.http.plugin.jwt_validator.algorithm: RS256
      easyhaproxy.http.plugin.jwt_validator.issuer: https://auth.example.com/
      easyhaproxy.http.plugin.jwt_validator.audience: https://api.example.com
      easyhaproxy.http.plugin.jwt_validator.pubkey_path: /etc/haproxy/jwt_keys/api_pubkey.pem
    volumes:
      - ./pubkey.pem:/etc/haproxy/jwt_keys/api_pubkey.pem:ro

Skip issuer/audience validation:

labels:
  easyhaproxy.http.plugin.jwt_validator.issuer: none
  easyhaproxy.http.plugin.jwt_validator.audience: none
  easyhaproxy.http.plugin.jwt_validator.pubkey_path: /etc/haproxy/jwt_keys/api_pubkey.pem

HAProxy config generated:

# JWT Validator - Validate JWT tokens
http-request deny content-type 'text/html' string 'Missing Authorization HTTP header' unless { req.hdr(authorization) -m found }

# Extract JWT header and payload
http-request set-var(txn.alg) http_auth_bearer,jwt_header_query('$.alg')
http-request set-var(txn.iss) http_auth_bearer,jwt_payload_query('$.iss')
http-request set-var(txn.aud) http_auth_bearer,jwt_payload_query('$.aud')
http-request set-var(txn.exp) http_auth_bearer,jwt_payload_query('$.exp','int')

# Validate JWT
http-request deny content-type 'text/html' string 'Unsupported JWT signing algorithm' unless { var(txn.alg) -m str RS256 }
http-request deny content-type 'text/html' string 'Invalid JWT issuer' unless { var(txn.iss) -m str https://auth.example.com/ }
http-request deny content-type 'text/html' string 'Invalid JWT audience' unless { var(txn.aud) -m str https://api.example.com }
http-request deny content-type 'text/html' string 'Invalid JWT signature' unless { http_auth_bearer,jwt_verify(txn.alg,"/etc/haproxy/jwt_keys/api_pubkey.pem") -m int 1 }

# Validate expiration
http-request set-var(txn.now) date()
http-request deny content-type 'text/html' string 'JWT has expired' if { var(txn.exp),sub(txn.now) -m int lt 0 }

What it validates:

• ✅ Authorization header presence
• ✅ JWT signing algorithm (RS256, RS512, etc.)
• ✅ JWT issuer (if configured)
• ✅ JWT audience (if configured)
• ✅ JWT signature using public key
• ✅ JWT expiration time

Important: Requires HAProxy 2.5+ with JWT support. Mount public key file as read-only volume.

Configuration Methods

Plugins can be configured using three methods, listed in order of precedence (highest to lowest):

1. Container Labels (Domain Plugins Only)

Enable and configure domain plugins for specific containers:

services:
  webapp:
    image: myapp:latest
    labels:
      easyhaproxy.http.host: example.com
      easyhaproxy.http.port: 80
      # Enable multiple plugins
      easyhaproxy.http.plugins: cloudflare,deny_pages
      # Configure deny_pages plugin
      easyhaproxy.http.plugin.deny_pages.paths: /admin,/api/internal
      easyhaproxy.http.plugin.deny_pages.status_code: 403

Label format:

• Enable plugins: easyhaproxy.<definition>.plugins: plugin1,plugin2
• Configure plugin: easyhaproxy.<definition>.plugin.<plugin_name>.<config_key>: value

Where <definition> is: http, https, tcp, etc.

2. Static YAML Configuration

Configure plugins globally in /etc/haproxy/static/config.yaml:

plugins:
  # Global settings
  abort_on_error: false  # Log and continue on errors (recommended)

  # Enable global plugins
  enabled: [cleanup]

  # Configure individual plugins
  config:
    cloudflare:
      enabled: true
      ip_list_path: /etc/haproxy/cloudflare_ips.lst

    cleanup:
      enabled: true
      max_idle_time: 600

    deny_pages:
      enabled: false  # Disable globally, enable per-container via labels

3. Environment Variables

Configure plugins via environment variables:

# Global settings
EASYHAPROXY_PLUGINS_ENABLED=cleanup
EASYHAPROXY_PLUGINS_ABORT_ON_ERROR=false

# Plugin-specific configuration
EASYHAPROXY_PLUGIN_CLEANUP_ENABLED=true
EASYHAPROXY_PLUGIN_CLEANUP_MAX_IDLE_TIME=600
EASYHAPROXY_PLUGIN_CLOUDFLARE_IP_LIST_PATH=/etc/haproxy/cloudflare_ips.lst

Variable format:

• Enable plugins: EASYHAPROXY_PLUGINS_ENABLED=plugin1,plugin2
• Configure plugin: EASYHAPROXY_PLUGIN_<PLUGIN_NAME>_<CONFIG_KEY>=value

Common Use Cases

Protect API with JWT Authentication

Secure your API endpoints with JWT token validation:

services:
  api:
    labels:
      easyhaproxy.http.host: api.example.com
      easyhaproxy.http.plugins: jwt_validator
      easyhaproxy.http.plugin.jwt_validator.issuer: https://auth0.myapp.com/
      easyhaproxy.http.plugin.jwt_validator.audience: https://api.example.com
      easyhaproxy.http.plugin.jwt_validator.pubkey_path: /etc/haproxy/jwt_keys/api_pubkey.pem
    volumes:
      - ./auth_pubkey.pem:/etc/haproxy/jwt_keys/api_pubkey.pem:ro

Restrict Admin Panel to Office IPs

Protect admin panel by only allowing access from office network:

labels:
  easyhaproxy.http.host: admin.example.com
  easyhaproxy.http.plugins: ip_whitelist
  easyhaproxy.http.plugin.ip_whitelist.allowed_ips: 203.0.113.0/24,198.51.100.42

Protect Admin Paths

Block access to WordPress admin and other sensitive paths:

labels:
  easyhaproxy.http.host: wordpress.example.com
  easyhaproxy.http.plugins: deny_pages
  easyhaproxy.http.plugin.deny_pages.paths: /wp-admin,/wp-login.php,/.env
  easyhaproxy.http.plugin.deny_pages.status_code: 404

Cloudflare IP Restoration

Restore original visitor IPs for applications behind Cloudflare:

labels:
  easyhaproxy.http.host: myapp.com
  easyhaproxy.http.plugins: cloudflare

Multiple Plugins Together

Combine multiple plugins for one domain:

labels:
  easyhaproxy.http.host: secure-app.com
  easyhaproxy.http.plugins: cloudflare,deny_pages
  easyhaproxy.http.plugin.deny_pages.paths: /admin,/config
  easyhaproxy.http.plugin.deny_pages.status_code: 403

Automatic Cleanup

Keep your system clean with automatic temp file removal:

# /etc/haproxy/static/config.yaml
plugins:
  enabled: [cleanup]
  config:
    cleanup:
      enabled: true
      max_idle_time: 3600  # 1 hour

Error Handling

Log and Continue (Recommended)

By default, plugin errors are logged as warnings and discovery continues:

plugins:
  abort_on_error: false  # Default

When to use: Most situations. Ensures a failing plugin doesn't prevent HAProxy updates.

Behavior:

• Plugin errors logged as warnings
• Discovery cycle continues
• Other plugins still execute
• HAProxy config is generated without the failed plugin

Abort on Error

Stop discovery cycle if any plugin fails:

plugins:
  abort_on_error: true

When to use: Critical plugins where failure should halt deployment.

Behavior:

• Plugin error stops discovery
• Previous HAProxy config remains active
• No configuration changes until issue is resolved

Troubleshooting

Enable Debug Logging

See detailed plugin execution information:

EASYHAPROXY_LOG_LEVEL=DEBUG

Look for:

INFO: Loaded builtin plugin: cloudflare (domain)
INFO: Loaded builtin plugin: cleanup (global)
DEBUG: Executing domain plugin: cloudflare for domain: example.com
DEBUG: Plugin cloudflare metadata: {'domain': 'example.com', 'ip_list_path': '/etc/haproxy/cloudflare_ips.lst'}

Plugin Not Loading

Check:

1. Plugin file exists in /etc/haproxy/plugins/ or builtin directory
2. Python syntax is valid
3. Plugin class inherits from PluginInterface
4. Check logs for load errors

Plugin Not Executing

For domain plugins:

1. Check container has label: easyhaproxy.http.plugins: plugin_name
2. Verify plugin name is correct (case-sensitive)
3. Enable debug logging

For global plugins:

1. Check YAML config: plugins.enabled: [plugin_name]
2. Or env var: EASYHAPROXY_PLUGINS_ENABLED=plugin_name
3. Enable debug logging

Configuration Not Applied

Check precedence order:

1. Container labels (highest)
2. YAML configuration
3. Environment variables (lowest)

Container labels override YAML and env vars.

Plugin Output Missing

Verify:

1. Plugin is enabled (enabled: true)
2. Plugin configuration is correct
3. Plugin's process() method returns valid PluginResult
4. Check debug logs for plugin execution

Best Practices

1. Start with log-and-continue mode - Use abort_on_error: false until you're confident plugins are stable
2. Use container labels for domain-specific config - Easier to manage per-service
3. Use YAML/env for global config - Better for global plugins and defaults
4. Enable debug logging during testing - Helps identify configuration issues
5. Test plugin changes in staging first - Avoid production surprises
6. Keep plugin configurations simple - Use defaults when possible

Limitations

• Plugins must be written in Python
• Domain plugins execute for each domain, so keep them lightweight
• Plugins cannot modify the Jinja2 template structure directly
• Plugin errors in abort mode prevent all configuration updates

Creating Custom Plugins

To create your own plugins, see the Plugin Developer Guide.

Further Reading

• Plugin Developer Guide - Create custom plugins
• Container Labels - Label configuration reference
• Environment Variables - Environment variable reference
• Static Configuration - YAML configuration reference