Step 5: Storage

Configure persistent storage, secrets, and configuration data for your container.

Persistent Volume Claims (PVCs)

Create persistent storage that survives container restarts:

Automatic Volume Creation

When enabled, volumes are automatically created and mounted:

PVC Name: Descriptive identifier (e.g., data-storage)
Storage Size: Disk space allocation (e.g., 1GB)
Access Mode: ReadWriteOnce (RWO) for single-pod access
Storage Class: Performance tier (e.g., fast-ssd)

Volumes

Define storage volumes for your container:

Volume Configuration

Volume Name: Internal identifier (e.g., data-volume)
Volume Type: Empty Directory for temporary storage
Size Limit: Optional storage constraint

Volume Mounts

Connect volumes to container filesystem paths:

Volume Name: Reference to defined volume
Mount Path: Container filesystem location (e.g., /data or /config)
Read Only: Checkbox for write protection
Purpose: Mount volumes before creating mounts

Secrets

Store sensitive configuration data securely:

Secret Configuration

Secret Name: Identifier (e.g., db-credentials)
Secret Type: Opaque (Generic) for key-value pairs
Key: Configuration key (e.g., password, token)
Value: Sensitive data (automatically encrypted)

Example Secrets:

db-credentials:
  username: myapp
  password: [encrypted]
  
api-tokens:
  github_token: [encrypted]
  stripe_key: [encrypted]

ConfigMaps

Store non-sensitive configuration data:

ConfigMap Configuration

ConfigMap Name: Identifier (e.g., app-config)
Key: Configuration parameter (e.g., config.yaml, database_url)
Value: Configuration content or file data

Example ConfigMaps:

app-config:
  database_url: postgresql://localhost:5432/myapp
  redis_url: redis://localhost:6379/0
  
nginx-config:
  nginx.conf: |
    server {
      listen 80;
      server_name localhost;
      ...
    }

Storage Types and Use Cases

Persistent Volumes

When to Use:

Database data that must survive pod restarts
User-uploaded files and media
Application logs that need retention
Cache data that should persist

Configuration Examples:

# Database storage
name: postgres-data
size: 20Gi
mount: /var/lib/postgresql/data

# Application uploads
name: app-uploads
size: 50Gi
mount: /app/uploads

Temporary Volumes

When to Use:

Temporary processing files
Cache that can be rebuilt
Inter-container communication
Scratch space for computations

Configuration Examples:

# Temporary cache
name: cache-volume
type: EmptyDir
mount: /tmp/cache

# Processing workspace
name: workspace
type: EmptyDir
mount: /workspace

Secrets

When to Use:

Database passwords
API keys and tokens
TLS certificates
OAuth credentials

Configuration Examples:

# Database credentials
name: db-secret
keys:
  username: dbuser
  password: securepassword
  
# API keys
name: api-keys
keys:
  stripe_key: sk_live_...
  github_token: ghp_...

ConfigMaps

When to Use:

Application configuration files
Environment-specific settings
Non-sensitive configuration data
Feature flags and toggles

Configuration Examples:

# Application config
name: app-config
data:
  config.json: |
    {
      "debug": false,
      "timeout": 30000
    }
    
# Nginx configuration
name: nginx-config
data:
  nginx.conf: |
    server {
      listen 80;
      root /var/www/html;
    }

Storage Classes and Performance

Available Storage Classes

Standard: General-purpose SSD storage
Fast-SSD: High-performance SSD for databases
Bulk: Cost-effective for large data sets
NFS: Network file system for shared access

Performance Considerations

IOPS: Input/output operations per second
Throughput: Data transfer rates
Latency: Response time for storage operations
Durability: Data protection and backup capabilities

Common Storage Patterns

Database Applications

# PostgreSQL storage
name: postgres-data
size: 20Gi
storageClass: fast-ssd
mount: /var/lib/postgresql/data

# Database backups
name: postgres-backup
size: 50Gi
storageClass: standard
mount: /backups

Web Applications

# Static assets
name: static-files
size: 5Gi
storageClass: standard
mount: /app/static

# User uploads
name: user-uploads
size: 100Gi
storageClass: standard
mount: /app/uploads

Logging and Analytics

# Application logs
name: app-logs
size: 10Gi
storageClass: bulk
mount: /var/log/app

# Analytics data
name: analytics
size: 200Gi
storageClass: bulk
mount: /data/analytics