fix: Gitea Traefik routing and connection pool optimization

- Remove middleware reference from Gitea Traefik labels (caused routing issues)
- Optimize Gitea connection pool settings (MAX_IDLE_CONNS=30, authentication_timeout=180s)
- Add explicit service reference in Traefik labels
- Fix intermittent 504 timeouts by improving PostgreSQL connection handling

Fixes Gitea unreachability via git.michaelschiemer.de

deployment/stacks/redis/README.md

@@ -0,0 +1,291 @@
+# Redis Stack
+
+External Redis Stack for the Custom PHP Framework application.
+
+## Overview
+
+This Redis Stack provides:
+- **Cache Backend**: Application-level caching (sessions, query results, objects)
+- **Queue Backend**: Background job queue storage
+- **Session Storage**: User session persistence
+- **Rate Limiting**: Request rate limiting storage
+
+**Architecture Pattern**: Following the same external stack pattern as PostgreSQL for consistency and separation of concerns.
+
+## Quick Start
+
+```bash
+# 1. Create environment configuration
+cp .env.example .env
+
+# 2. Set Redis password
+echo "REDIS_PASSWORD=$(openssl rand -base64 32)" >> .env
+
+# 3. Create app-internal network (if not exists)
+docker network create app-internal
+
+# 4. Start Redis Stack
+docker compose up -d
+
+# 5. Verify health
+docker compose ps
+docker compose exec redis-stack redis-cli ping
+# Expected: PONG
+```
+
+## Configuration
+
+### Environment Variables
+
+```env
+REDIS_PASSWORD=your-secure-password   # Required for production
+TZ=Europe/Berlin                      # Timezone for logs
+```
+
+### Redis Configuration
+
+Redis configuration is in `redis.conf` with production-optimized settings:
+
+**Persistence:**
+- RDB Snapshots: 15min/5min/1min intervals
+- AOF (Append Only File): `everysec` fsync policy
+- Combined persistence for data durability
+
+**Memory Management:**
+- Max Memory: 512MB (configurable)
+- Eviction Policy: `allkeys-lru` (Least Recently Used)
+- Lazy freeing for async deletion
+
+**Performance:**
+- TCP keepalive: 300s
+- Active rehashing enabled
+- Optimized client output buffers
+
+### Security
+
+**Password Protection:**
+```bash
+# Set via Docker Secrets (recommended)
+echo "your-redis-password" | docker secret create redis_password -
+
+# Or via environment variable
+REDIS_PASSWORD=your-password docker compose up -d
+```
+
+**Network Isolation:**
+- Only accessible via `app-internal` Docker network
+- Not exposed to public internet
+- Protected mode enabled
+
+## Health Monitoring
+
+```bash
+# Check Redis health
+docker compose exec redis-stack redis-cli ping
+
+# Get Redis info
+docker compose exec redis-stack redis-cli info
+
+# Monitor real-time activity
+docker compose exec redis-stack redis-cli monitor
+
+# Check memory usage
+docker compose exec redis-stack redis-cli info memory
+
+# View slow queries
+docker compose exec redis-stack redis-cli slowlog get 10
+```
+
+## Integration with Application Stack
+
+### Production Setup
+
+```bash
+# In application root directory
+docker compose \
+  -f docker-compose.base.yml \
+  -f docker-compose.production.yml \
+  -f docker-compose.postgres-override.yml \
+  -f docker-compose.redis-override.yml \
+  up -d
+```
+
+### Application Environment Variables
+
+```env
+REDIS_HOST=redis-stack      # Container name from this stack
+REDIS_PORT=6379
+REDIS_PASSWORD=your-password  # Same as Redis Stack password
+```
+
+## Maintenance
+
+### Backup
+
+Redis persistence is handled automatically via:
+- **RDB**: Snapshot backups in `/data/dump.rdb`
+- **AOF**: Append-only log in `/data/appendonly.aof`
+
+**Manual Backup:**
+```bash
+# Trigger immediate RDB snapshot
+docker compose exec redis-stack redis-cli BGSAVE
+
+# Copy backup files
+docker cp redis-stack:/data/dump.rdb ./backups/redis-$(date +%Y%m%d).rdb
+```
+
+### Restore
+
+```bash
+# Stop Redis
+docker compose stop redis-stack
+
+# Restore backup
+docker cp ./backups/redis-backup.rdb redis-stack:/data/dump.rdb
+
+# Start Redis
+docker compose start redis-stack
+```
+
+### Cleanup
+
+```bash
+# Clear specific database
+docker compose exec redis-stack redis-cli -n 0 FLUSHDB
+
+# Clear all databases (DANGEROUS!)
+docker compose exec redis-stack redis-cli FLUSHALL
+
+# Remove old AOF/RDB files
+docker compose exec redis-stack sh -c "rm -f /data/*.aof.old /data/*.rdb.old"
+```
+
+## Performance Tuning
+
+### Memory Optimization
+
+```bash
+# Check memory fragmentation
+docker compose exec redis-stack redis-cli info memory | grep fragmentation
+
+# Defragment if needed (Redis 4.0+)
+docker compose exec redis-stack redis-cli MEMORY PURGE
+```
+
+### Connection Limits
+
+Adjust `maxclients` in `redis.conf` based on your application needs:
+```conf
+maxclients 10000  # Default, increase if needed
+```
+
+### Persistence Trade-offs
+
+**For Cache-Only Usage:**
+```conf
+# Disable persistence for maximum performance
+save ""
+appendonly no
+```
+
+**For Critical Data:**
+```conf
+# More frequent snapshots
+save 300 1
+save 60 10
+appendfsync always  # Slower but safest
+```
+
+## Troubleshooting
+
+### Connection Issues
+
+```bash
+# Test connection from application container
+docker exec php sh -c 'redis-cli -h redis-stack -a $REDIS_PASSWORD ping'
+
+# Check network connectivity
+docker network inspect app-internal
+```
+
+### Memory Issues
+
+```bash
+# Check current memory usage
+docker compose exec redis-stack redis-cli info memory
+
+# View evicted keys
+docker compose exec redis-stack redis-cli info stats | grep evicted
+
+# Increase memory limit (edit docker-compose.yml)
+# deploy.resources.limits.memory: 1G
+```
+
+### Performance Issues
+
+```bash
+# Check slow queries
+docker compose exec redis-stack redis-cli slowlog get 10
+
+# Monitor commands in real-time
+docker compose exec redis-stack redis-cli monitor
+
+# Analyze key patterns
+docker compose exec redis-stack redis-cli --bigkeys
+```
+
+## Architecture
+
+### Network Topology
+
+```
+┌─────────────────────────────────────────┐
+│          app-internal Network           │
+│                                         │
+│  ┌──────────┐         ┌──────────────┐ │
+│  │   PHP    │────────▶│ redis-stack  │ │
+│  │   App    │         │   (Cache)    │ │
+│  └──────────┘         └──────────────┘ │
+│                                         │
+│  ┌──────────┐                           │
+│  │  Queue   │────────▶                  │
+│  │  Worker  │         (Shared Redis)    │
+│  └──────────┘                           │
+│                                         │
+└─────────────────────────────────────────┘
+```
+
+### Data Separation
+
+**Database Indexes:**
+- DB 0: Application cache (default)
+- DB 1: Session storage
+- DB 2: Queue backend
+- DB 3: Rate limiting
+- DB 4-15: Available for other uses
+
+## Best Practices
+
+1. **Always use passwords** in production
+2. **Monitor memory usage** - set appropriate `maxmemory` limit
+3. **Enable persistence** for critical data (sessions, queue)
+4. **Regular backups** if using Redis as primary data store
+5. **Network isolation** - never expose Redis port publicly
+6. **Health checks** - monitor Redis availability
+7. **Resource limits** - set Docker memory limits
+8. **Logging** - check Redis logs for issues
+
+## Related Documentation
+
+- [Application Docker Compose](../../docker-compose.production.yml)
+- [Redis Override Configuration](../../docker-compose.redis-override.yml)
+- [PostgreSQL Stack](../postgresql/README.md) (similar pattern)
+- [Redis Official Documentation](https://redis.io/documentation)
+
+## Support
+
+For issues or questions:
+- Check Redis logs: `docker compose logs redis-stack`
+- Test connectivity: `docker compose exec redis-stack redis-cli ping`
+- Review configuration: `docker compose exec redis-stack redis-cli config get '*'`