H2O HTTP Server

intermediate

Optimized HTTP/1.x and HTTP/2 server with high performance.

Overview

H2O is a high-performance HTTP/1.x and HTTP/2 server developed by DeNA and optimized for speed and efficiency. Written in C with a focus on memory efficiency and low latency, H2O consistently ranks among the fastest web servers in benchmarks, particularly excelling at HTTP/2 connections and TLS termination. The server supports advanced features like HTTP/2 server push, mruby scripting for request manipulation, and sophisticated caching mechanisms that make it ideal for performance-critical applications. This Docker configuration deploys H2O with a custom configuration file and web content directory, enabling rapid deployment of a production-grade HTTP/2 server. The setup includes both HTTP and HTTPS ports with volume mounts for configuration and static content, making it suitable for high-traffic websites, API endpoints, and applications requiring optimal HTTP/2 performance. Organizations seeking maximum performance per resource unit will find H2O particularly valuable, as it delivers exceptional throughput while maintaining low memory footprint compared to traditional servers like Apache or Nginx. The mruby integration allows for sophisticated request handling logic without the overhead of external scripting languages, making this stack perfect for edge computing scenarios and latency-sensitive applications.

Key Features

Native HTTP/2 support with server push capabilities for preloading critical resources
mruby scripting integration for dynamic request handling and response manipulation
Extremely low memory footprint with efficient connection multiplexing
Advanced TLS optimization with session resumption and OCSP stapling
Built-in access logging with customizable format and rotation
Hot configuration reloading without connection drops
Sophisticated caching layer with cache-aware optimization
High-performance static file serving with sendfile optimization

Common Use Cases

1High-traffic content delivery networks requiring maximum throughput per server
2API gateways for microservices architectures demanding low latency responses
3Edge computing deployments where resource efficiency is critical
4Development environments testing HTTP/2 server push implementations
5Load balancer frontends for distributing traffic across backend services
6Static website hosting with advanced caching and compression requirements
7WebSocket proxy servers handling thousands of concurrent connections

Prerequisites

Docker and Docker Compose installed with support for bind mounts
At least 512MB available RAM for optimal H2O performance
Ports 80 and 443 available on the host system
Basic understanding of YAML configuration format for h2o.conf
SSL/TLS certificates if enabling HTTPS functionality
Knowledge of HTTP/2 concepts for advanced feature utilization

For development & testing. Review security settings, change default credentials, and test thoroughly before production use. See Terms

docker-compose.yml

1services: 
2  h2o: 
3    image: lkwg82/h2o-http2-server:latest
4    container_name: h2o
5    restart: unless-stopped
6    volumes: 
7      - ./h2o/h2o.conf:/etc/h2o/h2o.conf:ro
8      - ./html:/var/www/html:ro
9    ports: 
10      - "80:80"
11      - "443:443"
12    networks: 
13      - h2o-network
14
15networks: 
16  h2o-network: 
17    driver: bridge

.env Template

.env

1# H2O configuration file required

Usage Notes

1Docs: https://h2o.examp1e.net/configure.html
2HTTP/2 optimized - excellent TLS performance
3Server push support for preloading assets
4mruby scripting for request handling logic
5Configure via h2o.conf - YAML format
6Benchmarks show among fastest HTTP/2 servers

Quick Start

terminal

1# 1. Create the compose file
2cat > docker-compose.yml << 'EOF'
3services:
4  h2o:
5    image: lkwg82/h2o-http2-server:latest
6    container_name: h2o
7    restart: unless-stopped
8    volumes:
9      - ./h2o/h2o.conf:/etc/h2o/h2o.conf:ro
10      - ./html:/var/www/html:ro
11    ports:
12      - "80:80"
13      - "443:443"
14    networks:
15      - h2o-network
16
17networks:
18  h2o-network:
19    driver: bridge
20EOF
21
22# 2. Create the .env file
23cat > .env << 'EOF'
24# H2O configuration file required
25EOF
26
27# 3. Start the services
28docker compose up -d
29
30# 4. View logs
31docker compose logs -f

One-Liner

Run this command to download and set up the recipe in one step:

terminal

1curl -fsSL https://docker.recipes/api/recipes/h2o/run | bash

Troubleshooting

Container fails to start with 'configuration file not found': Ensure ./h2o/h2o.conf exists and contains valid YAML syntax
Permission denied accessing configuration files: Check that h2o.conf has appropriate read permissions (644) for the container user
HTTP/2 connections falling back to HTTP/1.1: Verify TLS is properly configured as HTTP/2 requires encryption in most browsers
High memory usage despite H2O's efficiency: Check mruby scripts for memory leaks or inefficient string operations
Static files not serving correctly: Ensure ./html directory exists with proper permissions and contains index files
Server push not working as expected: Verify push directives in h2o.conf and test with HTTP/2 capable tools like curl --http2

Community Notes

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