Redis Persistence

Configure Redis data persistence and high availability

Overview

Redis provides caching and state management for Smallest Self-Host. This guide covers configuring Redis persistence, high availability, and performance optimization.

Redis Deployment Options

Option 1: Embedded Redis (Default)

Smallest Self-Host includes Redis as a subchart.

Advantages:

• Simple setup
• Automatic configuration
• Included in Helm chart

Disadvantages:

• Single point of failure
• No data persistence by default
• Limited to cluster resources

Configuration:

values.yaml

redis:
  enabled: true
  auth:
    enabled: true
    password: "your-secure-password"
  master:
    persistence:
      enabled: false
  replica:
    replicaCount: 1
    persistence:
      enabled: false

Option 2: External Redis

Use Amazon ElastiCache or self-managed Redis.

Advantages:

• Managed service (ElastiCache)
• High availability
• Better performance
• Independent scaling

Disadvantages:

• Additional cost
• More complex setup

Configuration:

values.yaml

redis:
  enabled: false
  externalHost: "my-redis.abc123.0001.use1.cache.amazonaws.com"
  port: 6379
  ssl: false
  auth:
    enabled: true
    password: "redis-password"

Enable Redis Persistence

With Embedded Redis

Enable AOF (Append-Only File) persistence:

values.yaml

redis:
  enabled: true
  auth:
    enabled: true
    password: "your-secure-password"
  master:
    persistence:
      enabled: true
      storageClass: "gp3"
      size: 8Gi
      accessModes:
        - ReadWriteOnce
  replica:
    replicaCount: 2
    persistence:
      enabled: true
      storageClass: "gp3"
      size: 8Gi

This creates:

• 1 master pod with persistent volume
• 2 replica pods with persistent volumes
• Automatic failover

Verify Persistence

Check PVCs created:

kubectl get pvc -n smallest | grep redis

Expected output:

redis-data-smallest-redis-master-0    Bound    8Gi
redis-data-smallest-redis-replicas-0  Bound    8Gi
redis-data-smallest-redis-replicas-1  Bound    8Gi

High Availability

Sentinel Mode

Redis Sentinel provides automatic failover:

values.yaml

redis:
  enabled: true
  sentinel:
    enabled: true
    quorum: 2
  master:
    persistence:
      enabled: true
      size: 8Gi
  replica:
    replicaCount: 2
    persistence:
      enabled: true
      size: 8Gi

Cluster Mode

For very high throughput:

values.yaml

redis:
  enabled: true
  architecture: replication
  master:
    count: 3
  replica:
    replicaCount: 2

AWS ElastiCache Integration

Create ElastiCache Cluster

Using AWS Console:

1. Navigate to ElastiCache

   AWS Console → ElastiCache → Redis → Create

2. Cluster Settings

   • Cluster mode: Disabled (for simplicity)
   • Name: smallest-redis
   • Engine version: 7.0+
   • Node type: cache.r6g.large (or larger)
3. Subnet Group

   Select subnet group in same VPC as EKS cluster

4. Security

   • Security group: Allow port 6379 from EKS cluster
   • Encryption in transit: Enabled
   • Encryption at rest: Enabled
5. Backup

   • Automatic backups: Enabled
   • Retention: 7 days
6. Create

   Review and create (takes 10-15 minutes)

   Note the Primary endpoint

Configure Helm Chart

values.yaml

redis:
  enabled: false
  externalHost: "smallest-redis.abc123.0001.use1.cache.amazonaws.com"
  port: 6379
  ssl: true
  auth:
    enabled: false

lightningAsr:
  env:
    - name: REDIS_URL
      value: "rediss://smallest-redis.abc123.0001.use1.cache.amazonaws.com:6379"
    - name: REDIS_TLS
      value: "true"

Performance Tuning

Memory Configuration

Set memory limits for embedded Redis:

values.yaml

redis:
  master:
    resources:
      limits:
        memory: 2Gi
      requests:
        memory: 1Gi
  replica:
    resources:
      limits:
        memory: 2Gi
      requests:
        memory: 1Gi

Eviction Policy

Configure memory eviction:

values.yaml

redis:
  master:
    configuration: |
      maxmemory-policy allkeys-lru
      maxmemory 1gb

Disable Persistence for Performance

For non-critical data (faster performance):

values.yaml

redis:
  master:
    configuration: |
      save ""
      appendonly no
    persistence:
      enabled: false

Without persistence, all data is lost if Redis restarts. Only use for truly ephemeral data.

Monitoring Redis

Check Redis Status

kubectl get pods -l app.kubernetes.io/name=redis -n smallest

Connect to Redis CLI

kubectl exec -it <redis-pod> -n smallest -- redis-cli

Inside redis-cli:

AUTH your-password
INFO
DBSIZE
KEYS *

Monitor Memory Usage

kubectl exec -it <redis-pod> -n smallest -- redis-cli INFO memory

Monitor Performance

kubectl exec -it <redis-pod> -n smallest -- redis-cli INFO stats

Backup and Recovery

Manual Backup

Create snapshot:

kubectl exec -it <redis-master-pod> -n smallest -- redis-cli BGSAVE

Copy RDB file:

kubectl cp <redis-master-pod>:/data/dump.rdb ./redis-backup.rdb -n smallest

Scheduled Backups

Create CronJob for automatic backups:

redis-backup-cronjob.yaml

apiVersion: batch/v1
kind: CronJob
metadata:
  name: redis-backup
  namespace: smallest
spec:
  schedule: "0 2 * * *"
  jobTemplate:
    spec:
      template:
        spec:
          containers:
          - name: backup
            image: redis:7-alpine
            command:
              - sh
              - -c
              - |
                redis-cli -h smallest-redis-master BGSAVE
                sleep 60
                kubectl cp smallest-redis-master-0:/data/dump.rdb /backup/redis-$(date +%Y%m%d).rdb
            volumeMounts:
              - name: backup
                mountPath: /backup
          volumes:
            - name: backup
              persistentVolumeClaim:
                claimName: redis-backup-pvc
          restartPolicy: OnFailure

Restore from Backup

kubectl cp ./redis-backup.rdb <redis-master-pod>:/data/dump.rdb -n smallest

kubectl exec -it <redis-master-pod> -n smallest -- redis-cli SHUTDOWN NOSAVE

kubectl delete pod <redis-master-pod> -n smallest

Pod will restart and load from backup.

Security

Enable Authentication

Always use password authentication:

values.yaml

redis:
  auth:
    enabled: true
    password: "strong-random-password"

Or use existing secret:

values.yaml

redis:
  auth:
    enabled: true
    existingSecret: "redis-secret"
    existingSecretPasswordKey: "redis-password"

Enable TLS

For embedded Redis:

values.yaml

redis:
  tls:
    enabled: true
    authClients: true
    certFilename: "tls.crt"
    certKeyFilename: "tls.key"
    certCAFilename: "ca.crt"

Network Policies

Restrict access to Redis:

redis-network-policy.yaml

apiVersion: networking.k8s.io/v1
kind: NetworkPolicy
metadata:
  name: redis-policy
  namespace: smallest
spec:
  podSelector:
    matchLabels:
      app.kubernetes.io/name: redis
  policyTypes:
    - Ingress
  ingress:
    - from:
        - podSelector:
            matchLabels:
              app: lightning-asr
        - podSelector:
            matchLabels:
              app: api-server
      ports:
        - protocol: TCP
          port: 6379

Scaling Redis

Vertical Scaling

Increase resources:

values.yaml

redis:
  master:
    resources:
      limits:
        memory: 4Gi
        cpu: 2

Restart pods:

kubectl rollout restart statefulset smallest-redis-master -n smallest

Horizontal Scaling

Add more replicas:

values.yaml

redis:
  replica:
    replicaCount: 3

Troubleshooting

Connection Refused

Check Redis pod is running:

kubectl get pods -l app.kubernetes.io/name=redis -n smallest
kubectl logs -l app.kubernetes.io/name=redis -n smallest

Test connection:

kubectl run redis-test --rm -it --restart=Never \
  --image=redis:7-alpine \
  --command -- redis-cli -h smallest-redis-master -a your-password ping

Out of Memory

Check memory usage:

kubectl exec -it <redis-pod> -n smallest -- redis-cli INFO memory

Increase memory limit or enable eviction:

redis:
  master:
    resources:
      limits:
        memory: 4Gi
    configuration: |
      maxmemory-policy allkeys-lru

Slow Performance

Check latency:

kubectl exec -it <redis-pod> -n smallest -- redis-cli --latency

Check slow queries:

kubectl exec -it <redis-pod> -n smallest -- redis-cli SLOWLOG GET 10

Data Loss

Check if persistence is enabled:

kubectl exec -it <redis-pod> -n smallest -- redis-cli CONFIG GET save
kubectl exec -it <redis-pod> -n smallest -- redis-cli CONFIG GET appendonly

Best Practices

Always Use Authentication

Enable password authentication even for internal Redis:

redis:
  auth:
    enabled: true
    password: "strong-password"

Enable Persistence for Production

Use AOF for maximum durability:

redis:
  master:
    persistence:
      enabled: true
    configuration: |
      appendonly yes
      appendfsync everysec

Use Replicas for HA

At least 2 replicas for high availability:

redis:
  replica:
    replicaCount: 2

Monitor Redis Metrics

Use Redis exporter for Prometheus:

helm install redis-exporter prometheus-community/prometheus-redis-exporter \
  --set redisAddress=redis://smallest-redis-master:6379

Regular Backups

Schedule automatic backups:

• ElastiCache: Enable automatic backups
• Self-managed: Use CronJob for BGSAVE

What’s Next?

HPA Configuration

Configure autoscaling for Lightning ASR

Metrics Setup

Set up Prometheus metrics collection