Redis Caching Configuration

Borg UI includes an intelligent caching system that can provide 600x faster archive browsing using Redis. The cache system automatically compresses large archives and gracefully falls back to in-memory caching when Redis is unavailable.

Overview

Performance Impact

Redis caching transforms the browsing experience:Without cache: 5-10 seconds per archive (depending on size)With cache: ~10ms per archive (after first load)Speedup: Up to 600x faster for large archives

How It Works

First Browse: Archive contents loaded via borg list (slow)
Cached: Results compressed and stored in Redis with TTL
Subsequent Browses: Served instantly from cache (fast)
Automatic Refresh: Cache expires after TTL, rebuilds on next access

Cache Architecture

┌─────────────────┐
│   Borg UI App   │
└────────┬────────┘
         │
         ├─────────────┐
         │             │
    ┌────▼───┐    ┌────▼─────┐
    │ Redis  │    │ In-Memory│
    │ Cache  │    │ Fallback │
    └────────┘    └──────────┘
    (Primary)      (Backup)

Dual Backend System:

Redis: Primary cache (persistent, shared across restarts)
In-Memory: Automatic fallback (when Redis unavailable)

Quick Setup

The default Docker Compose configuration includes Redis:

docker-compose.yml

services:
  app:
    environment:
      - REDIS_HOST=redis
      - REDIS_PORT=6379
      - CACHE_TTL_SECONDS=7200  # 2 hours
      - CACHE_MAX_SIZE_MB=2048  # 2GB
    depends_on:
      redis:
        condition: service_healthy

  redis:
    image: redis:7-alpine
    command: >
      redis-server
      --maxmemory 2gb
      --maxmemory-policy allkeys-lru
      --save ""
      --appendonly no

Redis starts automatically with Borg UI. No additional configuration needed for local setup.

Configuration Options

Environment Variables

string

default:"none"

External Redis connection URL. Takes precedence over REDIS_HOST/REDIS_PORT.Formats:

TCP: redis://hostname:port/db
TCP with password: redis://:password@hostname:port/db
TLS: rediss://hostname:port/db
Unix socket: unix:///run/redis.sock?db=0

Examples:

# Remote Redis
REDIS_URL=redis://192.168.1.100:6379/0

# With password
REDIS_URL=redis://:mypassword@redis.example.com:6379/0

# TLS connection
REDIS_URL=rediss://secure-redis.example.com:6380/0

# Unix socket
REDIS_URL=unix:///var/run/redis/redis.sock?db=0

string

default:"redis"

Redis server hostname. Used if REDIS_URL is not set.Set to "disabled" to disable Redis and use only in-memory cache.

REDIS_HOST=redis

integer

default:"6379"

Redis server port.

REDIS_PORT=6379

integer

default:"0"

Redis database number (0-15).

REDIS_DB=0

string

default:"none"

Redis server password (if authentication enabled).

REDIS_PASSWORD=your-redis-password

integer

default:"7200"

Cache time-to-live in seconds. Archive data cached for this duration.Default: 2 hours (7200 seconds)Recommendations:

Static archives: 14400 (4 hours) or higher
Active backups: 3600 (1 hour) or lower
Development: 300 (5 minutes)

CACHE_TTL_SECONDS=7200

integer

default:"2048"

Maximum in-memory cache size in megabytes (fallback backend only).Default: 2GB (2048 MB)

CACHE_MAX_SIZE_MB=2048

UI Configuration

Cache settings can also be configured via Settings → Cache in the web UI.UI settings override environment variables and persist to the database.

Configurable via UI:

Redis URL (external Redis)
Cache TTL
Cache size limit
Enable/disable caching

Redis Memory Configuration

Default Configuration

docker-compose.yml

redis:
  command: >
    redis-server
    --maxmemory 2gb
    --maxmemory-policy allkeys-lru
    --save ""
    --appendonly no

Flags explained:

Flag	Purpose	Default
`--maxmemory`	Maximum memory limit	2GB
`--maxmemory-policy`	Eviction policy when full	allkeys-lru
`--save ""`	Disable RDB snapshots	Disabled
`--appendonly`	Disable AOF persistence	Disabled

Persistence is disabled because Redis is used purely as a cache. Data loss on restart is acceptable since the cache rebuilds automatically.

Eviction Policies

allkeys-lru (Recommended):

Evicts least recently used keys from all keys
Best for pure cache use case
Automatically removes old archives to make room

Alternatives:

allkeys-lfu: Evict least frequently used (better for hot data)
volatile-lru: Only evict keys with TTL set
volatile-ttl: Evict keys with shortest TTL first

Memory Sizing

Estimation formula:

Cache Size ≈ (Avg Archive Size × Number of Archives × Compression Ratio)

Compression:

Archives 100KB: Automatically compressed (zlib level 6)
Typical compression: 30-50% of original size
Archives 100KB: Stored uncompressed

Examples:

Archives	Avg Size	Compressed	Recommended Redis
100	1MB	~40MB	512MB
500	5MB	~1GB	2GB
1000	10MB	~3GB	4GB
5000	2MB	~3GB	4GB

Set maxmemory slightly higher than estimated to prevent constant evictions.

Adjusting Memory Limits

docker-compose.yml

redis:
  command: >
    redis-server
    --maxmemory 4gb
    --maxmemory-policy allkeys-lru

.env

CACHE_MAX_SIZE_MB=4096

External Redis Setup

Shared Redis Instance

docker-compose.yml

services:
  app:
    environment:
      - REDIS_URL=redis://shared-redis.internal.lan:6379/0
    # Remove local redis service

Redis with Authentication

.env

REDIS_URL=redis://:your-password@redis.example.com:6379/0

TLS/SSL Connection

.env

REDIS_URL=rediss://secure-redis.example.com:6380/0

Multiple Borg UI Instances

Share one Redis instance across multiple Borg UI deployments:

docker-compose.yml

services:
  app1:
    environment:
      - REDIS_URL=redis://shared-redis:6379/0
  
  app2:
    environment:
      - REDIS_URL=redis://shared-redis:6379/1  # Different DB
  
  shared-redis:
    image: redis:7-alpine
    command: redis-server --maxmemory 8gb

Use different Redis databases (0-15) to isolate cache data between instances.

Cache Management

View Cache Statistics

UI: Settings → Cache → Statistics API:

GET /api/cache/stats

Response

{
  "backend": "redis",
  "available": true,
  "connection_type": "local",
  "connection_info": "redis:6379/0",
  "hits": 1523,
  "misses": 127,
  "hit_rate": 92.3,
  "size_bytes": 157286400,
  "entry_count": 245,
  "ttl_seconds": 7200,
  "max_size_mb": 2048
}

Clear Cache

POST /api/cache/clear

POST /api/cache/clear-repository
Content-Type: application/json

{
  "repo_id": 1
}

Use cases:

After pruning archives
After deleting archives
Testing/troubleshooting
Repository structure changed

Cache Keys

Format: archive:{repo_id}:{archive_name} Examples:

archive:1:backup-2026-02-28T10:00:00
archive:5:weekly-2026-W09
archive:12:daily-monday

Manual Redis Access

# Connect to Redis container
docker exec -it borg-redis redis-cli

# View all cache keys
KEYS archive:*

# Get cache entry count
DBSIZE

# View memory usage
INFO memory

# Clear entire database
FLUSHDB

# Test connection
PING

In-Memory Fallback

When It Activates

Automatic fallback to in-memory cache when:

Redis connection fails
Redis not configured (REDIS_HOST=disabled)
Redis unavailable during startup
Redis fails 3+ consecutive operations

Limitations

Feature	Redis	In-Memory
Persistence	Survives restart	Lost on restart
Shared	Multi-instance	Single instance
Size limit	Set via maxmemory	Set via CACHE_MAX_SIZE_MB
Eviction	Configurable	LRU only
Performance	Excellent	Good

Disabling Redis

.env

REDIS_HOST=disabled

docker-compose.yml

services:
  app:
    environment:
      - REDIS_HOST=disabled
      - CACHE_MAX_SIZE_MB=2048
    # Remove depends_on redis

# Remove redis service

Performance Tuning

Large Repositories (>1000 archives)

docker-compose.yml

redis:
  command: >
    redis-server
    --maxmemory 8gb
    --maxmemory-policy allkeys-lru
    --tcp-backlog 511
    --timeout 0
    --tcp-keepalive 300

.env

CACHE_TTL_SECONDS=14400  # 4 hours
CACHE_MAX_SIZE_MB=8192   # 8GB

Very Large Archives (>500MB each)

.env

CACHE_TTL_SECONDS=86400  # 24 hours (if archives rarely change)

redis:
  command: >
    redis-server
    --maxmemory 16gb
    --maxmemory-policy allkeys-lru

High-Traffic Deployments

redis:
  command: >
    redis-server
    --maxmemory 4gb
    --maxmemory-policy allkeys-lfu  # Least frequently used
    --maxclients 10000

Low-Memory Environments

redis:
  command: >
    redis-server
    --maxmemory 512mb
    --maxmemory-policy allkeys-lru

.env

CACHE_TTL_SECONDS=1800   # 30 minutes
CACHE_MAX_SIZE_MB=512

Monitoring

Health Checks

Redis health check:

healthcheck:
  test: ["CMD", "redis-cli", "ping"]
  interval: 10s
  timeout: 3s
  retries: 3

Check status:

docker-compose ps redis

Redis Logs

# View Redis logs
docker-compose logs -f redis

# Check for errors
docker-compose logs redis | grep -i error

Performance Metrics

# Connect to Redis
docker exec -it borg-redis redis-cli

# View info
INFO stats
INFO memory
INFO persistence

# Monitor commands in real-time
MONITOR

# Slow query log
SLOWLOG GET 10

Troubleshooting

Redis Connection Failed

Symptoms:

Redis health check failed: Connection refused
Fallback to in-memory cache

Solutions:

Check Redis is running:
docker-compose ps redis
Check Redis logs:
docker-compose logs redis
Restart Redis:
docker-compose restart redis
Verify network:
docker exec -it borg-web-ui ping redis

Out of Memory

Symptoms:

OOM command not allowed when used memory > 'maxmemory'

Solutions:

Increase Redis memory:

redis:
  command: redis-server --maxmemory 4gb

Lower TTL to expire data faster:
CACHE_TTL_SECONDS=3600

Manually clear cache:

docker exec -it borg-redis redis-cli FLUSHDB

Slow Performance

Symptoms: Cache hit rate 80%, slow archive browsing Solutions:

Check hit rate:

docker exec -it borg-redis redis-cli INFO stats | grep hit_rate

Increase TTL:
CACHE_TTL_SECONDS=14400 # 4 hours

Increase memory:

redis:
  command: redis-server --maxmemory 4gb

Check Redis is actually being used:

docker exec -it borg-redis redis-cli DBSIZE

Cache Not Updating

Symptoms: New archives not showing, stale data displayed Solutions:

Clear repository cache:

POST /api/cache/clear-repository
{"repo_id": 1}

Check TTL expiration:

docker exec -it borg-redis redis-cli TTL archive:1:archive-name

Verify archive name matches cache key

Best Practices

Use Redis for Production

Always use Redis in production. The in-memory fallback is for emergency/testing only.

Set Appropriate TTL

Balance freshness vs performance:

Static archives: Longer TTL (4-24 hours)
Active backups: Shorter TTL (1-2 hours)
Development: Very short TTL (5-30 minutes)

Size Redis Appropriately

Allocate 2-4x the average total archive size (compressed) for optimal hit rates.

Monitor Hit Rate

Target 90%+ hit rate. If lower, increase memory or TTL.

Disable Persistence

Redis is a cache - disable RDB/AOF to improve performance and reduce disk I/O.

Clear After Major Changes

Manually clear cache after pruning, deleting archives, or restructuring repositories.

Use External Redis for Scale

Share one Redis instance across multiple Borg UI deployments for better resource utilization.

Next Steps

Environment Variables

Complete cache environment variable reference

Docker Compose

Advanced Docker Compose configurations

Performance Optimization

Advanced performance tuning guide

API Reference

Cache management API documentation

​Redis Caching Configuration

​Overview

​Performance Impact

​How It Works

​Cache Architecture

​Quick Setup

​Configuration Options

​Environment Variables

​UI Configuration

​Redis Memory Configuration

​Default Configuration

​Eviction Policies

​Memory Sizing

​Adjusting Memory Limits

​External Redis Setup

​Shared Redis Instance

​Redis with Authentication

​TLS/SSL Connection

​Multiple Borg UI Instances

​Cache Management

​View Cache Statistics

​Clear Cache

​Cache Keys

​Manual Redis Access

​In-Memory Fallback

​When It Activates

​Limitations

​Disabling Redis

​Performance Tuning

​Large Repositories (>1000 archives)

​Very Large Archives (>500MB each)

​High-Traffic Deployments

​Low-Memory Environments

​Monitoring

​Health Checks

​Redis Logs

​Performance Metrics

​Troubleshooting

​Redis Connection Failed

​Out of Memory

​Slow Performance

​Cache Not Updating

​Best Practices

​Next Steps

Environment Variables

Docker Compose

Performance Optimization

API Reference

Redis Caching Configuration

Overview

Performance Impact

How It Works

Cache Architecture

Quick Setup

Configuration Options

Environment Variables

UI Configuration

Redis Memory Configuration

Default Configuration

Eviction Policies

Memory Sizing

Adjusting Memory Limits

External Redis Setup

Shared Redis Instance

Redis with Authentication

TLS/SSL Connection

Multiple Borg UI Instances

Cache Management

View Cache Statistics

Clear Cache

Cache Keys

Manual Redis Access

In-Memory Fallback

When It Activates

Limitations

Disabling Redis

Performance Tuning

Large Repositories (>1000 archives)

Very Large Archives (>500MB each)

High-Traffic Deployments

Low-Memory Environments

Monitoring

Health Checks

Redis Logs

Performance Metrics

Troubleshooting

Redis Connection Failed

Out of Memory

Slow Performance

Cache Not Updating

Best Practices

Next Steps