🐳 memcached-docker

A deep-optimized Memcached (1.6.38) Docker suite focused on stripping the server down to its absolute essentials—producing some of the smallest and most secure Memcached images available. Each variant is engineered to remove unnecessary features, binaries, and files, creating ultra-compact, scratch-based containers ready for production.

Built for:

• ✅ Maximum minimalism: Images as small as ~124 KB (amd64).
• ✅ No clutter: Zero shell, zero OS—just Memcached.
• ✅ Container-native configuration: Full environment variable support (no CLI args required).
• ✅ Variants: micro, slim, tls, full—scale up or down to match your needs.

Multi-arch support:

Architecture
linux/386	✅
linux/amd64	✅
linux/arm/v6	✅
linux/arm/v7	✅
linux/arm64/v8	✅
linux/ppc64le	✅
linux/s390x	✅

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📌 Purpose

Purpose: This project’s core mission is to shrink Memcached as much as possible while keeping it fast, secure, and flexible—ideal for cloud, edge, and microservice environments.

• ✅ Zero-config: Fully operational out of the box with environment variable support.
• ✅ Optimized builds: From minimal (micro) to fully-featured (full).
• ✅ Platform-agnostic: Multi-architecture support (x86, ARM, etc.).

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🚀 Why Tiny & Scratch-Based?

🔹 Ultra-Small Image Size

Architecture	Image Size
linux/amd64	🚀 123.97 KB ✅
linux/386	133.05 KB
linux/arm/v7	132.77 KB
linux/arm/v6	129.43 KB
linux/arm64/v8	126.94 KB
linux/ppc64le	135.63 KB
linux/s390x	161.00 KB

✅ ~124 KB for amd64? That’s next-level lightweight.

Benefits:

• 🚀 Faster pulls & deploys: Minimal size means near-instant startup—critical for CI/CD and edge.
• 🔒 Smaller attack surface: Fewer bits = fewer vulnerabilities.
• 🌍 Low bandwidth/storage: Ideal for constrained environments (IoT, microVMs, etc.).

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🔹 Scratch Base Advantages

• 🧼 Nothing extra: scratch = no shell, no libc, no package manager—only Memcached itself.
• 🔐 Locked down: No way to exec or misuse the image—great for high-security setups.
• 🛠 Predictable: No hidden base layers; what you ship is exactly what runs.
• ✅ Audit-friendly: Minimal image = simpler compliance and auditing.

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🚀 Image Variants

Image Tag	Features
tigersmile/memcached:micro	🟢 Minimal build: - TCP only (no UDP/socket) - Binary & text protocols - No TLS, SASL, or extstore
tigersmile/memcached:slim	🟢 Mid-tier: - TCP only - Enhanced features for higher load - No TLS
tigersmile/memcached:tls	🟢 Adds TLS: - TCP only - TLS encryption - No SASL
tigersmile/memcached:full	🟢 Fully-featured: - TCP only - TLS + SASL + extstore

🛑 Note: All variants exclusively support TCP traffic—no UNIX socket or UDP support.

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🛠 Features

• ✅ Environment-driven configuration (no CLI args needed)
• ✅ TLS support (tls/full)
• ✅ SASL support (full)
• ✅ Extstore support (full)
• ✅ Alpine-based minimal size
• ✅ Scratch containers (no shell, no extras)

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📥 Usage Example

docker run -d \
  --name my-memcached \
  -e MEMCACHED_MEMORY_LIMIT=512 \
  -e MEMCACHED_CONNECTIONS=1024 \
  tigersmile/memcached:micro

CLI arguments are optional:

docker run -d \
  --name my-memcached \
  tigersmile/memcached:micro -m 512 -c 1024

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🔐 TLS Setup

1️⃣ Generate certs:

mkdir certs
openssl req -x509 -newkey rsa:4096 -sha256 -days 365 \
  -nodes -keyout certs/server.key -out certs/server.crt \
  -subj "/CN=localhost"

2️⃣ Launch TLS container:

docker run -d \
  --name memcached-tls \
  -e MEMCACHED_TLS=1 \
  -e MEMCACHED_TLS_CERT=/certs/server.crt \
  -e MEMCACHED_TLS_KEY=/certs/server.key \
  -v $(pwd)/certs:/certs:ro \
  tigersmile/memcached:tls

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🗄️ Extstore Setup

docker run -d \
  --name memcached-full \
  -e MEMCACHED_EXTSTORE_PATH=/extstore:1G \
  -v /path/to/extstore:/extstore \
  tigersmile/memcached:full

Customizable with:

• MEMCACHED_EXTSTORE_PAGE_SIZE
• MEMCACHED_EXTSTORE_WBUF_SIZE

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📊 Environment Variables Overview

Variable	Description	micro	slim	tls	full
MEMCACHED_MEMORY_LIMIT	Memory limit (MB)	✅	✅	✅	✅
MEMCACHED_CONNECTIONS	Max simultaneous connections	✅	✅	✅	✅
MEMCACHED_THREADS	Number of worker threads	✅	✅	✅	✅
MEMCACHED_PROTOCOL	Protocol (ascii, binary, auto)	✅	✅	✅	✅
MEMCACHED_REQS_PER_EVENT	Max requests per event	✅	✅	✅	✅
MEMCACHED_FACTOR	Slab growth factor	✅	✅	✅	✅
MEMCACHED_MAX_ITEM_SIZE	Max item size	✅	✅	✅	✅
MEMCACHED_MIN_ITEM_SIZE	Min item size	✅	✅	✅	✅
MEMCACHED_LISTEN_BACKLOG	Listen backlog size	✅	✅	✅	✅
MEMCACHED_KEY_DELIMITER	Key delimiter character	✅	✅	✅	✅
MEMCACHED_ALLOW_SHUTDOWN	Enable ASCII shutdown command	✅	✅	✅	✅
MEMCACHED_DISABLE_CAS	Disable CAS	✅	✅	✅	✅
MEMCACHED_LOCK_PAGES	Lock paged memory	✅	✅	✅	✅
MEMCACHED_ENABLE_COREDUMPS	Enable coredumps	✅	✅	✅	✅
MEMCACHED_ENABLE_LARGEPAGES	Enable large pages	✅	✅	✅	✅
MEMCACHED_DISABLE_FLUSH_ALL	Disable flush_all command	❌	✅	✅	✅
MEMCACHED_DISABLE_DUMPING	Disable stats cachedump/lru_crawler metadump	❌	✅	✅	✅
MEMCACHED_DISABLE_WATCH	Disable watch commands	❌	✅	✅	✅
MEMCACHED_VERBOSE	Verbosity level	✅	✅	✅	✅
MEMCACHED_SASL	Enable SASL authentication	❌	❌	❌	✅
MEMCACHED_TLS	Enable TLS	❌	❌	✅	✅
MEMCACHED_TLS_CERT	TLS certificate path	❌	❌	✅	✅
MEMCACHED_TLS_KEY	TLS key path	❌	❌	✅	✅
MEMCACHED_TLS_CA	TLS CA certificate path	❌	❌	✅	✅
MEMCACHED_TLS_VERIFY_MODE	TLS verify mode	❌	❌	✅	✅
MEMCACHED_EXTSTORE_PATH	Extstore path + size	❌	✅	✅	✅
MEMCACHED_EXTSTORE_PAGE_SIZE	Extstore page size	❌	✅	✅	✅
MEMCACHED_EXTSTORE_WBUF_SIZE	Extstore write buffer size	❌	✅	✅	✅
MEMCACHED_EXTSTORE_THREADS	Extstore thread count	❌	✅	✅	✅
MEMCACHED_EXTSTORE_ITEM_SIZE	Extstore item size	❌	✅	✅	✅
MEMCACHED_EXTSTORE_ITEM_AGE	Extstore item age	❌	✅	✅	✅
MEMCACHED_EXTSTORE_LOW_TTL	Extstore low TTL	❌	✅	✅	✅
MEMCACHED_EXTSTORE_DROP_UNREAD	Extstore drop unread flag	❌	✅	✅	✅
MEMCACHED_EXTSTORE_RECACHE_RATE	Extstore recache rate	❌	✅	✅	✅
MEMCACHED_EXTSTORE_COMPACT_UNDER	Extstore compact threshold	❌	✅	✅	✅
MEMCACHED_EXTSTORE_DROP_UNDER	Extstore drop threshold	❌	✅	✅	✅
MEMCACHED_EXTSTORE_MAX_FRAG	Extstore max fragmentation	❌	✅	✅	✅
MEMCACHED_EXTSTORE_MAX_SLEEP	Extstore max sleep time	❌	✅	✅	✅
MEMCACHED_SLAB_AUTOMOVE_FREERATIO	Slab automove freeratio	✅	✅	✅	✅
MEMCACHED_NAPI_IDS	NAPI IDs	✅	✅	✅	✅

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This table lists all supported environment variables, with checkmarks showing which variants implement each. Memcached maps them automatically if the feature is available.

⚠️ Notes

• TCP-only: All builds exclusively support TCP (no UNIX/UDP).
• Scratch containers: No shell or package manager.
• Flexible config: Env vars auto-map to CLI options; CLI args still work.
• Ulimits: High concurrency may require raising limits:

ulimits:
  nofile:
    soft: 65535
    hard: 65535

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🔗 Links

• 🐙 GitHub: https://github.com/johnnyjoy/memcached-docker
• 🐋 Docker Hub: tigersmile/memcached

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✅ Status

• ✅ Multi-arch builds: x86, ARM (32 & 64-bit), PPC, s390x.
• ✅ Fully environment-configurable.
• ✅ TLS & extstore tested.
• 🚧 SASL: implemented but pending full test suite.

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Enjoy lightning-fast, container-optimized Memcached 🚀