Community Requests

Replicating Redis Cluster with Sentinel

Hi *, I'm still trying to wrap my head around the above setup. There is a github repo (https://github.com/tritonDataCenter/triton-redis-cluster), that sets up a replicating redis sentinel cluster on Triton Datacenter. It basically patches the redis.conf depending from the fact, that a master already exists (or not). As I understand, sentinel is managing the cluster after the initial setup. Thus you just create one node first (count = 1) and then scale up afterwards. I guess, that should be somehow be doable maybe with lifecycle tasks and templates. I don't know, wether (consul?) DNS is even needed. If that works, you might even be able to use autoscaling to expand the number of cluster nodes dynamically. I tried to get Qwen3.6 to spit something out along those lines. But obviously there is no such thing as Nomad DNS but maybe one could use IP addresses, too: # redis-sentinel-replicated.nomad # Enhanced Nomad job: 3 Redis nodes (1 master + 2 replicas) + 3 Sentinel nodes # Inspired by tritonDataCenter/triton-redis-cluster replication pattern job "redis-sentinel-replicated" { datacenters = ["dc1"] type = "service" # ────────────────────────────────────────────────────────────────────────────── # REDIS CLUSTER (Master + Replicas) # ────────────────────────────────────────────────────────────────────────────── group "redis" { count = 3 restart { attempts = 3 interval = "5m" delay = "15s" mode = "delay" } task "redis" { driver = "docker" config { image = "redis:7-alpine" network_mode = "bridge" port_map = { redis = 6379 } } ports = ["redis"] # Persistent volume for replication durability volume "redis_data" { source = "redis_data" target = "/data" } # Dynamic config: Index 0 → Master, Others → Replica template { data = <<-EOT port 6379 bind 0.0.0.0 protected-mode no requirepass {{ env "REDIS_PASSWORD" | default "SecureRedisPass123!" }} masterauth {{ env "REDIS_PASSWORD" | default "SecureRedisPass123!" }} dir /data appendonly yes save 900 1 save 300 10 save 60 10000 replica-announce-ip {{ env "NOMAD_ADDR_redis" }} {{ if eq (env "NOMAD_ALLOC_INDEX") "0" }} # I am the master {{ else }} replicaof redis-master.service.redis.dc1.nomad.local 6379 {{ end }} EOT destination = "tmp/redis.conf" env = true } command = "redis-server" args = ["/tmp/redis.conf"] service { name = "redis-master" port = "redis" } check { type = "tcp" port = "redis" interval = "10s" timeout = "2s" } resources { cpu = 500 memory = 512 } } volume "redis_data" { type = "host" source = "/opt/redis/data" # Replace with CSI path for production } } # ────────────────────────────────────────────────────────────────────────────── # SENTINEL NODES # ────────────────────────────────────────────────────────────────────────────── group "sentinel" { count = 3 restart { attempts = 3 interval = "5m" delay = "15s" mode = "delay" } task "sentinel" { driver = "docker" config { image = "redis:7-alpine" network_mode = "bridge" port_map = { sentinel = 26379 } } ports = ["sentinel"] # Sentinel config: monitors master via Nomad DNS, re-resolves on failover template { data = <<-EOT port 26379 bind 0.0.0.0 sentinel monitor mymaster redis-master.service.redis.dc1.nomad.local 6379 2 sentinel auth-pass mymaster {{ env "REDIS_PASSWORD" | default "SecureRedisPass123!" }} sentinel down-after-milliseconds mymaster 5000 sentinel failover-timeout mymaster 60000 sentinel parallel-syncs mymaster 1 sentinel deny-scripts-reconfig yes sentinel resolve-hostnames yes EOT destination = "tmp/sentinel.conf" env = true } command = "redis-sentinel" args = ["/tmp/sentinel.conf"] service { name = "sentinel" port = "sentinel" } check { type = "tcp" port = "sentinel" interval = "10s" timeout = "2s" } resources { cpu = 250 memory = 128 } } } }