Apache HTTP Server

The Apache HTTP Server (commonly "httpd" or simply "Apache") is one of the most widely deployed web servers in the world. It is a mature, modular server that can act as a static web server, a reverse proxy, a load balancer, and a TLS terminator. This guide focuses on running Apache in containers with Docker, covering reverse proxying, load balancing, HTTPS with Let's Encrypt, security hardening, monitoring, and performance tuning.

The examples use the official httpd image (Apache 2.4). Its configuration lives at /usr/local/apache2/conf/httpd.conf, extra config snippets go in /usr/local/apache2/conf/extra/, and the default document root is /usr/local/apache2/htdocs/.

Apache vs Nginx

Both Apache and Nginx are production-grade web servers; the right choice depends on the workload. They are also frequently combined — Nginx as an edge cache/reverse proxy in front of Apache application servers.

	Apache HTTP Server	Nginx
Architecture	Process/thread-based (MPMs: prefork, worker, event)	Event-driven, asynchronous
Configuration	Central config plus per-directory `.htaccess` overrides	Central config, no per-directory files
Dynamic content	In-process modules (`mod_php`, `mod_wsgi`)	Proxies to external processes (PHP-FPM, etc.)
Module loading	Dynamic — modules load at runtime via `LoadModule`	Mostly compile-time (dynamic modules since 1.9.11)
Strengths	`.htaccess` flexibility, huge module ecosystem	High concurrency, low memory footprint

Modules

Apache's capabilities come from modules that must be enabled with LoadModule. The official image ships them, but many are commented out by default. This guide uses:

Module	Purpose
`mod_proxy`, `mod_proxy_http`	Reverse proxying to backend servers
`mod_proxy_balancer`, `mod_lbmethod_*`	Load balancing across backends
`mod_ssl`	TLS/HTTPS termination
`mod_headers`	Add or modify request/response headers
`mod_rewrite`	URL rewriting and redirects
`mod_deflate`, `mod_cache`, `mod_cache_disk`	Compression and caching
`mod_status`	Runtime server status page

Enable a module by uncommenting (or adding) its LoadModule line in httpd.conf:

LoadModule proxy_module        modules/mod_proxy.so
LoadModule proxy_http_module   modules/mod_proxy_http.so
LoadModule ssl_module          modules/mod_ssl.so
LoadModule headers_module      modules/mod_headers.so
LoadModule rewrite_module      modules/mod_rewrite.so

In This Section

Reverse Proxy — Apache as a reverse proxy with mod_proxy and name-based virtual hosts, using Docker
Load Balancing — mod_proxy_balancer, balancing methods, sticky sessions, health checks, and the balancer manager
TLS / Let's Encrypt — HTTPS with mod_ssl and automated certificates via Let's Encrypt (Certbot) on the host and in Docker
Security and Hardening — security response headers, information-disclosure hardening, and access control
Monitoring and Troubleshooting — mod_status, logging, and solutions to common issues
Performance and Best Practices — MPM tuning, compression, caching, and operational best practices

Resources

Apache HTTP Server 2.4 Documentation
Apache Module Index
httpd Docker image
Mozilla SSL Configuration Generator — generates Apache TLS config
Apache Performance Tuning

Nginx — the event-driven alternative
ACME / Let's Encrypt (certificates section)
SSL vs TLS
Docker

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