Docker Volume Management

Implementation Reference

Source Files:

• packages/core/src/docker/volume.ts - Volume management operations
• packages/core/src/docker/docker-client.ts - Docker client implementation
• packages/core/src/operations/file.ts - File operations
• apps/xec/src/commands/copy.ts - Copy command implementation

Key Functions:

• VolumeManager.create() - Create volumes
• VolumeManager.remove() - Remove volumes
• VolumeManager.list() - List volumes
• VolumeManager.inspect() - Get volume details
• DockerClient.copyToContainer() - Copy files to container
• DockerClient.copyFromContainer() - Copy files from container

Overview

Xec provides comprehensive Docker volume management capabilities, enabling persistent data storage, file sharing between containers, and efficient data transfer between host and containers.

Volume Types

Named Volumes

Docker-managed volumes with persistent storage:

import { $ } from '@xec-sh/core';

// Create named volume
const volume = await $.docker.volume.create('app-data');

// Create with options
const volume = await $.docker.volume.create('db-data', {
  driver: 'local',
  driverOpts: {
    type: 'nfs',
    o: 'addr=10.0.0.1,rw',
    device: ':/data'
  },
  labels: {
    app: 'myapp',
    env: 'production'
  }
});

// Use in container
await $.docker.run('postgres', {
  volumes: ['db-data:/var/lib/postgresql/data']
});

Bind Mounts

Host directory mounts for development:

// Mount host directory
await $.docker.run('node:18', {
  volumes: [
    './src:/app/src:ro',           // Read-only
    './config:/app/config:rw',     // Read-write (default)
    './logs:/app/logs:delegated'   // Performance mode
  ]
});

// Absolute paths
await $.docker.run('nginx', {
  volumes: [
    '/etc/ssl/certs:/etc/nginx/certs:ro',
    '/var/www/html:/usr/share/nginx/html'
  ]
});

Tmpfs Mounts

In-memory temporary storage:

// Create tmpfs mount
await $.docker.run('alpine', {
  tmpfs: {
    '/tmp': 'size=100m',
    '/run': 'size=10m,mode=0755'
  }
});

// Or using mount syntax
await $.docker.run('alpine', {
  mounts: [{
    type: 'tmpfs',
    target: '/app/cache',
    tmpfsOptions: {
      size: 104857600,  // 100MB in bytes
      mode: 0755
    }
  }]
});

Volume Operations

Creating Volumes

Create and configure volumes:

// Create simple volume
await $.docker.volume.create('my-volume');

// Create with configuration
const volume = await $.docker.volume.create('backup-volume', {
  driver: 'local',
  driverOpts: {
    type: 'btrfs',
    device: '/dev/sdb1'
  }
});

// Create from another volume (clone)
await $.docker.volume.clone('source-volume', 'dest-volume');

Listing Volumes

List and filter volumes:

// List all volumes
const volumes = await $.docker.volume.list();

// Filter volumes
const appVolumes = await $.docker.volume.list({
  filters: {
    label: ['app=myapp'],
    name: ['app-*']
  }
});

// Get volume details
volumes.forEach(vol => {
  console.log({
    name: vol.Name,
    driver: vol.Driver,
    mountpoint: vol.Mountpoint,
    size: vol.UsageData?.Size,
    refCount: vol.UsageData?.RefCount
  });
});

Inspecting Volumes

Get detailed volume information:

// Inspect volume
const info = await $.docker.volume.inspect('my-volume');

console.log({
  name: info.Name,
  driver: info.Driver,
  mountpoint: info.Mountpoint,
  createdAt: info.CreatedAt,
  options: info.Options,
  labels: info.Labels,
  scope: info.Scope
});

// Check if volume exists
const exists = await $.docker.volume.exists('my-volume');

Removing Volumes

Remove unused volumes:

// Remove specific volume
await $.docker.volume.remove('old-volume');

// Force remove (even if in use)
await $.docker.volume.remove('data-volume', { force: true });

// Remove multiple volumes
const volumes = ['vol1', 'vol2', 'vol3'];
await Promise.all(
  volumes.map(v => $.docker.volume.remove(v))
);

// Prune unused volumes
const pruned = await $.docker.volume.prune();
console.log(`Removed ${pruned.SpaceReclaimed} bytes`);

File Operations

Copying to Containers

Transfer files from host to container:

// Copy file to container
await $.docker.copy('./app.js', 'my-container:/app/');

// Copy directory
await $.docker.copy('./src/', 'my-container:/app/src/');

// Copy with options
await $.docker.copyToContainer('my-container', {
  source: './config.json',
  destination: '/app/config.json',
  owner: '1000:1000',  // uid:gid
  mode: 0644
});

// Using CLI

# Copy file to container
xec copy config.json my-container:/app/

# Copy directory
xec copy ./src/ my-container:/app/src/

# Copy to multiple containers
xec copy config.json "containers.*:/app/"

Copying from Containers

Extract files from container to host:

// Copy file from container
await $.docker.copy('my-container:/app/output.log', './');

// Copy directory
await $.docker.copy('my-container:/app/dist/', './build/');

// Copy with archiving
await $.docker.copyFromContainer('my-container', {
  source: '/app/data/',
  destination: './backup.tar',
  compress: true
});

Bulk File Operations

Copy files between multiple containers:

// Copy between containers
await $.docker.copyBetween(
  'source-container:/app/data',
  'dest-container:/backup/'
);

// Sync directories
await $.docker.sync('container1:/data', 'container2:/data');

// Backup container volumes
async function backupVolumes(container: string) {
  const mounts = await $.docker.inspect(container)
    .then(info => info.Mounts);
    
  for (const mount of mounts) {
    if (mount.Type === 'volume') {
      await $.docker.copy(
        `${container}:${mount.Destination}`,
        `./backups/${mount.Name}/`
      );
    }
  }
}

Volume Sharing

Between Containers

Share volumes between containers:

// Create data container
await $.docker.run('busybox', {
  name: 'data-container',
  volumes: ['/data'],
  command: ['true']
});

// Use volumes from data container
await $.docker.run('ubuntu', {
  volumesFrom: ['data-container'],
  command: ['ls', '/data']
});

// Share specific volumes
await $.docker.run('app', {
  volumesFrom: ['data-container:ro'],  // Read-only
  volumes: ['shared-data:/app/shared']
});

Volume Drivers

Use different volume drivers:

// Local driver (default)
await $.docker.volume.create('local-vol', {
  driver: 'local'
});

// NFS volume
await $.docker.volume.create('nfs-vol', {
  driver: 'local',
  driverOpts: {
    type: 'nfs',
    o: 'addr=192.168.1.1,rw,nfsvers=4',
    device: ':/exports/data'
  }
});

// CIFS/SMB volume
await $.docker.volume.create('smb-vol', {
  driver: 'local',
  driverOpts: {
    type: 'cifs',
    o: 'username=user,password=pass,domain=DOMAIN',
    device: '//server/share'
  }
});

Backup and Restore

Volume Backup

Backup volume data:

// Backup volume to tar
async function backupVolume(volumeName: string) {
  const backupContainer = await $.docker.run('alpine', {
    volumes: [`${volumeName}:/source:ro`],
    command: ['tar', 'czf', '/backup.tar.gz', '/source'],
    detach: true
  });
  
  await $.docker.wait(backupContainer);
  await $.docker.copy(
    `${backupContainer}:/backup.tar.gz`,
    `./backups/${volumeName}-${Date.now()}.tar.gz`
  );
  await $.docker.remove(backupContainer);
}

// Backup with timestamp
await backupVolume('important-data');

Volume Restore

Restore volume from backup:

// Restore volume from tar
async function restoreVolume(volumeName: string, backupFile: string) {
  // Create new volume
  await $.docker.volume.create(volumeName);
  
  // Restore data
  const restoreContainer = await $.docker.run('alpine', {
    volumes: [`${volumeName}:/target`],
    command: ['tar', 'xzf', '/backup.tar.gz', '-C', '/target'],
    detach: true
  });
  
  await $.docker.copy(backupFile, `${restoreContainer}:/backup.tar.gz`);
  await $.docker.start(restoreContainer);
  await $.docker.wait(restoreContainer);
  await $.docker.remove(restoreContainer);
}

await restoreVolume('restored-data', './backup.tar.gz');

Performance Optimization

Mount Options

Optimize volume performance:

// macOS performance optimization
await $.docker.run('node', {
  volumes: [
    './src:/app/src:cached',       // Better read performance
    './node_modules:/app/node_modules:delegated',  // Better write performance
    './dist:/app/dist:consistent'  // Default consistency
  ]
});

// Linux optimizations
await $.docker.run('database', {
  volumes: ['db-data:/var/lib/mysql'],
  volumeDriver: 'local',
  storageOpt: {
    size: '10G'
  }
});

Volume Caching

Implement volume caching strategies:

// Use volume for dependencies
await $.docker.run('node', {
  volumes: [
    'npm-cache:/root/.npm',      // NPM cache
    'yarn-cache:/usr/local/share/.cache/yarn',  // Yarn cache
    './:/app'
  ]
});

// Build cache volume
await $.docker.volume.create('build-cache');
await $.docker.run('builder', {
  volumes: ['build-cache:/cache']
});

Configuration in Xec

Volume Configuration

Define volumes in .xec/config.yaml:

volumes:
  app-data:
    driver: local
    options:
      type: none
      o: bind
      device: /data/app
      
  db-backup:
    driver: local
    labels:
      backup: daily
      retention: 30d
      
  shared-cache:
    driver: local
    
targets:
  containers:
    app:
      type: docker
      container: my-app
      volumes:
        - app-data:/data
        - shared-cache:/cache
        - ./config:/app/config:ro

Volume Tasks

Define volume management tasks:

tasks:
  backup:
    description: Backup all volumes
    steps:
      - command: |
          for vol in $(docker volume ls -q); do
            docker run --rm -v ${vol}:/source:ro \
              -v ./backups:/backup alpine \
              tar czf /backup/${vol}-$(date +%Y%m%d).tar.gz /source
          done
          
  cleanup:
    description: Clean unused volumes
    steps:
      - command: docker volume prune -f
      
  migrate-volume:
    params:
      - name: source
      - name: destination
    steps:
      - command: |
          docker volume create ${params.destination}
          docker run --rm \
            -v ${params.source}:/source:ro \
            -v ${params.destination}:/dest \
            alpine cp -av /source/. /dest/

Performance Characteristics

Based on Implementation:

Operation Timings

• Volume Create: 10-50ms
• Volume Remove: 10-30ms
• Volume List: 5-20ms
• File Copy (small): 50-200ms
• File Copy (large): Depends on size and I/O
• Volume Backup: Depends on data size

Storage Performance

• Named Volumes: Native filesystem performance
• Bind Mounts: Host filesystem performance
• Tmpfs: Memory speed (fastest)
• NFS Volumes: Network dependent

Error Handling

Common Errors

Error	Code	Solution
Volume in use	8	Stop containers using volume
Permission denied	11	Check file permissions
No space left	7	Free up disk space
Volume not found	3	Verify volume name
Mount failed	8	Check mount source exists

Error Recovery

// Safe volume operations
async function safeVolumeCreate(name: string) {
  try {
    return await $.docker.volume.create(name);
  } catch (error) {
    if (error.message.includes('already exists')) {
      return await $.docker.volume.inspect(name);
    }
    throw error;
  }
}

// Cleanup on error
async function withVolume(name: string, fn: Function) {
  const volume = await $.docker.volume.create(name);
  try {
    return await fn(volume);
  } finally {
    await $.docker.volume.remove(name, { force: true });
  }
}

Best Practices

Volume Management

1. Use named volumes for persistent data
2. Bind mounts only for development
3. Set appropriate permissions on mounted files
4. Regular backups of important volumes
5. Clean up unused volumes periodically
6. Use labels for organization

Data Safety

// Always backup before operations
async function safeVolumeOperation(volume: string, operation: Function) {
  // Backup
  await backupVolume(volume);
  
  try {
    // Perform operation
    await operation();
  } catch (error) {
    // Restore on failure
    await restoreVolume(volume, `./backups/${volume}-latest.tar.gz`);
    throw error;
  }
}

// Verify data integrity
async function verifyVolume(volume: string) {
  const container = await $.docker.run('alpine', {
    volumes: [`${volume}:/data:ro`],
    command: ['find', '/data', '-type', 'f', '-exec', 'md5sum', '{}', '+']
  });
  
  return await $.docker.logs(container);
}

Related Topics

• Docker Overview - Docker basics
• Container Lifecycle - Container management
• Compose Integration - Multi-container apps
• Networking - Network configuration
• copy Command - File copy operations