Memcached

beginner

High-performance distributed memory caching system.

Overview

Memcached is a high-performance, distributed memory object caching system originally developed by LiveJournal in 2003 to reduce database load and improve application response times. As an open-source, in-memory key-value store, memcached operates as a simple caching layer that stores frequently accessed data in RAM, eliminating the need for repeated database queries or expensive computations. Its minimalist design focuses purely on speed and simplicity, making it one of the most widely adopted caching solutions for web applications. This Docker configuration deploys memcached using the Alpine Linux base image for minimal resource footprint while maintaining full functionality. The setup allocates 256MB of memory by default and exposes the standard memcached port 11211 for both text and binary protocol communications. The containerized approach ensures consistent memcached behavior across different environments while simplifying deployment and scaling operations. Developers building web applications, mobile backends, or API services will find this memcached deployment particularly valuable for reducing latency and database load. Startups experiencing rapid growth can implement this caching layer to handle increased traffic without immediately scaling their database infrastructure, while established companies can use it to optimize existing applications and reduce infrastructure costs through improved resource utilization.

Key Features

Memory-only storage with configurable allocation using -m flag parameter
Dual protocol support for both text-based telnet commands and binary protocol clients
LRU (Least Recently Used) eviction policy for automatic memory management when cache is full
Multi-threaded architecture with configurable connection limits and thread pools
Distributed caching support through consistent hashing across multiple memcached instances
Sub-millisecond response times for cache hits with minimal CPU overhead
Built-in statistics and monitoring through stats commands for performance analysis
Alpine Linux base image reducing container size to under 10MB for efficient deployment

Common Use Cases

1Session storage for web applications to enable horizontal scaling across multiple server instances
2Database query result caching to reduce load on MySQL, PostgreSQL, or MongoDB databases
3API response caching for frequently requested data in REST or GraphQL services
4Page fragment caching for dynamic websites to store rendered HTML components
5User profile and preference caching for social media platforms and user-driven applications
6Shopping cart data storage for e-commerce platforms requiring fast access to temporary data
7Rate limiting and throttling data storage for API gateways and security applications

Prerequisites

Docker Engine 20.10+ and Docker Compose V2 for container orchestration
Minimum 512MB available RAM on host system (256MB allocated to memcached by default)
Port 11211 available and not conflicting with existing services
Basic understanding of key-value caching concepts and TTL (Time To Live) principles
Network connectivity planning for client applications to reach memcached instance
Monitoring tools or scripts to track cache hit ratios and memory utilization

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

docker-compose.yml

1services: 
2  memcached: 
3    image: memcached:alpine
4    container_name: memcached
5    restart: unless-stopped
6    command: memcached -m 256
7    ports: 
8      - "11211:11211"
9    networks: 
10      - memcached-network
11
12networks: 
13  memcached-network: 
14    driver: bridge

.env Template

.env

1# Memcached default configuration

Usage Notes

1Docs: https://memcached.org/about
2Default port 11211 - text and binary protocols
3Simple key-value caching - no persistence by design
4Test: echo 'stats' | nc localhost 11211
5256MB memory by default - adjust with -m flag
6Ideal for session storage, query caching, page caching

Quick Start

terminal

1# 1. Create the compose file
2cat > docker-compose.yml << 'EOF'
3services:
4  memcached:
5    image: memcached:alpine
6    container_name: memcached
7    restart: unless-stopped
8    command: memcached -m 256
9    ports:
10      - "11211:11211"
11    networks:
12      - memcached-network
13
14networks:
15  memcached-network:
16    driver: bridge
17EOF
18
19# 2. Create the .env file
20cat > .env << 'EOF'
21# Memcached default configuration
22EOF
23
24# 3. Start the services
25docker compose up -d
26
27# 4. View logs
28docker 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/memcached/run | bash

Troubleshooting

Connection refused on port 11211: Verify container is running with 'docker ps' and check port mapping configuration
Out of memory errors or frequent evictions: Increase memory allocation by modifying '-m 256' to higher value like '-m 512' or '-m 1024'
Cache miss ratio too high: Check TTL settings in client applications and verify keys are being set correctly
Stats command returns no data: Use 'echo stats | nc localhost 11211' to verify memcached is responding properly
Container exits immediately: Check Docker logs for startup errors and verify command syntax in docker-compose configuration
Client connection timeouts: Adjust memcached connection limits with '-c' parameter or check network connectivity between services

Community Notes

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