Docker Storage

Docker Storage — 存储与数据持久化

Comprehensive guidance for managing persistent data in Docker.

When to Use

ALWAYS use this skill when the user mentions:

• "docker volume", "数据卷", "数据持久化"
• "bind mount", "tmpfs"
• "容器数据怎么保存", "数据不丢失"
• "数据库容器怎么持久化"
• "备份恢复", "存储驱动"

Storage Type Comparison

Visual Comparison

Volume:                       Bind Mount:               Tmpfs:
  Container                     Container                 Container
     │                              │                        │
  Docker-managed               /host/path                 Memory only
  /var/lib/docker/volumes/        ↕                     (no disk)
     ↕                         Container sees:              ↕
  Container sees:              /container/path           Container sees:
  /data                         = host files              /tmp (in RAM)

Volume Management

# Create & inspect
docker volume create mydata
docker volume ls
docker volume inspect mydata

# Use in container
docker run -v mydata:/var/lib/mysql mysql:8
docker run --mount source=mydata,target=/var/lib/mysql mysql:8  # explicit syntax (recommended)

# Cleanup
docker volume prune      # Remove unused volumes
docker volume rm mydata  # Remove specific volume

Named vs Anonymous Volumes

-v mydata:/data      → Named volume  (mydata) — survives container removal ✅
-v /data             → Anonymous volume — hard to identify later ❌

Bind Mount

# Read-write bind mount
docker run -v $(pwd)/app:/app nginx

# Read-only (protect host files)
docker run -v $(pwd)/config:/etc/nginx:ro nginx

# Explicit syntax
docker run --mount type=bind,source=$(pwd)/app,target=/app nginx

Tmpfs (Memory)

# Ephemeral data, never touches disk
docker run --tmpfs /tmp:rw,noexec,nosuid,size=64m nginx
docker run --mount type=tmpfs,destination=/tmp,tmpfs-size=64m nginx

Database Persistence Patterns

PostgreSQL

docker volume create pgdata
docker run -d \
  --name postgres \
  -e POSTGRES_PASSWORD=secret \
  -v pgdata:/var/lib/postgresql/data \
  -p 5432:5432 \
  postgres:16-alpine

MySQL

docker volume create mysqldata
docker run -d \
  --name mysql \
  -e MYSQL_ROOT_PASSWORD=secret \
  -v mysqldata:/var/lib/mysql \
  -v $(pwd)/my.cnf:/etc/mysql/conf.d/my.cnf:ro \
  -p 3306:3306 \
  mysql:8.4

Redis (Persistence)

docker volume create redisdata
docker run -d \
  --name redis \
  -v redisdata:/data \
  -p 6379:6379 \
  redis:7-alpine redis-server --appendonly yes

Backup & Restore

# Backup (using a temporary container)
docker run --rm \
  -v mysqldata:/source \
  -v $(pwd):/backup \
  alpine tar czf /backup/mysqldata-backup.tar.gz -C /source .

# Restore
docker run --rm \
  -v mysqldata:/target \
  -v $(pwd):/backup \
  alpine tar xzf /backup/mysqldata-backup.tar.gz -C /target

Storage Drivers

docker info | grep "Storage Driver"  # Check current

Workflow — 推荐配置流程

Step 1: 确定存储类型: 持久化数据 → Volume；开发热加载 → Bind Mount；临时缓存 → tmpfs Step 2: 创建 Volume: docker volume create db_data Step 3: 挂载到容器: docker run -v db_data:/var/lib/mysql mysql Step 4: 验证: docker volume inspect db_data + docker exec mysql ls /var/lib/mysql Step 5: 备份: docker run --rm -v db_data:/source -v $(pwd):/backup alpine tar czf /backup/db.tar.gz -C /source .

Gotchas — Common Pitfalls

• Anonymous volumes accumulate: Every -v /data (no name) creates a new anonymous volume. → Recovery: docker volume prune cleans all unused; use named volumes: -v mydata:/data.
• Bind mount paths: Must be absolute. → Recovery: -v $(pwd)/app:/app for docker run; -v ./app:/app works in Compose only.
• Permission issues with bind mounts: Container UID != host UID → permission denied. → Recovery: --user $(id -u):$(id -g) or RUN chown 1000:1000 /data in Dockerfile entrypoint.
• Data loss on container removal: Without -v, data is lost when container is removed. --rm flag even worse. → Recovery: Always use named volumes: docker run -v db_data:/var/lib/mysql.
• macOS bind mount performance: Bind mounts on Docker Desktop Mac are slow. → Recovery: Use :cached or :delegated mount options, or named volumes for better I/O.

Boundary — 能力边界（适用与不适用场景）

When NOT to Use This Skill

Security & Stability

• Use :ro for config files that containers should not modify.
• Never bind mount Docker socket (/var/run/docker.sock) without understanding the security implications.
• Backup volumes regularly, especially database volumes.
• No executable scripts bundled. Guidance only.

📚 官方文档参考

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FAQ

Q1: 如何快速上手此技能？ A: 参考上方的快速开始章节，按步骤操作即可。

Q2: 遇到版本不兼容问题怎么办？ A: 检查依赖版本，使用 lock 文件锁定，参考常见陷阱章节。

Q3: 如何在生产环境使用？ A: 参考最佳实践章节，确保配置正确，做好监控和日志。

Q4: 性能如何优化？ A: 参考性能优化相关文档，使用缓存、索引等手段。

Q5: 如何贡献或反馈问题？ A: 在 GitHub 仓库提交 Issue 或 Pull Request。

Q6: 是否支持中文？ A: 支持中文文档和中文注释，详见国内适配章节。