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To configure Redis Cluster on Ubuntu, run at least three Redis master nodes, put every instance in cluster mode, start all instances, and bootstrap them with redis-cli --cluster create. For a deployment that can tolerate a master failure, use six instances: three masters and one replica for each master. A successful bootstrap ends with [OK] All 16384 slots covered.
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The procedure below uses six local ports (7000–7005), explains the cluster-bus firewall rules, shows how to connect without MOVED errors, and covers validation, scaling, failover, persistence, and maintenance.
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Redis Cluster partitions keys across 16,384 hash slots. Master nodes serve those slots; replicas hold copies of masters and can be promoted during a failure.
| Layout | Nodes | What it provides | When to use it |
|---|---|---|---|
| Minimum working cluster | 3 masters | All slots can be assigned and the cluster can operate as a cluster. | Development, functional testing, or a tightly constrained environment. |
| Recommended deployment shape | 3 masters + 3 replicas (6 total) | One replica for every master, allowing replica promotion after a master failure. | Production-like deployments and serious staging environments. |
Redis describes three masters as the minimum cluster that works as expected and recommends six nodes for deployment. Put each master and its replica on separate hosts, availability zones, or other failure domains when your infrastructure permits it. The exact placement depends on your Ubuntu and hosting environment.
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Prerequisites and network plan
Prepare Ubuntu hosts
- Install Redis and the matching
redis-clifrom the package source appropriate for your Ubuntu release. - Reserve one writable data and configuration directory per Redis instance.
- Decide which address each node will advertise. A multi-host cluster must advertise addresses that every other node and every client can reach; loopback addresses such as
127.0.0.1are suitable only for a single-machine demonstration. - Plan durable storage for the generated cluster state file and persistence files, plus a recovery and backup procedure.
Reserve ports
This example runs instances on client ports 7000 through 7005. Redis Cluster also uses a separate cluster-bus port for node-to-node gossip, failure detection, and other cluster traffic. If you do not set an explicit cluster-port, the bus is the client port plus 10,000: 17,000 for port 7000, 17,001 for 7001, and so on.
| Instance | Client port | Default bus port when cluster-port is unset |
|---|---|---|
| Node 1 | 7000 | 17000 |
| Node 2 | 7001 | 17001 |
| Node 3 | 7002 | 17002 |
| Node 4 | 7003 | 17003 |
| Node 5 | 7004 | 17004 |
| Node 6 | 7005 | 17005 |
Allow client traffic to the ports your applications use and allow both client-port and cluster-bus traffic between every cluster member. Restrict those rules to trusted application and cluster networks rather than exposing Redis broadly.
Create one Redis instance per port
Make isolated directories
Each instance needs its own configuration, data, log, and generated cluster-state locations. A separate directory also lets every instance use the same relative cluster-config-file name without collisions.
sudo mkdir -p /srv/redis/7000 /srv/redis/7001 /srv/redis/7002
/srv/redis/7003 /srv/redis/7004 /srv/redis/7005Give the Redis service account ownership of the directories and ensure the account can write its persistence and generated node files. The exact service account and filesystem layout vary with the Ubuntu package and your service-management choice.
Write the per-instance configuration
Use this minimal configuration as the baseline for every instance. Change only the port and the paths that must be unique for that instance.
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port 7000
cluster-enabled yes
cluster-config-file nodes.conf
cluster-node-timeout 5000
appendonly yesportis the client port. Set it to 7000, 7001, 7002, 7003, 7004, or 7005 in the corresponding file.cluster-enabled yesturns the instance into a Redis Cluster node.cluster-config-file nodes.confnames the generated cluster configuration file. Redis creates and maintains this file; do not hand-edit it. Keep a separate working directory per instance so files do not overwrite one another.cluster-node-timeout 5000sets the example node-timeout value to 5,000 milliseconds.appendonly yesenables append-only persistence. Keep the append-only files on durable storage and include them in your recovery plan.
For a real deployment, set each instance’s data and log paths to its own writable directories and configure the addresses it must advertise. Do not copy a generated nodes.conf from one instance to another: node identity is created at runtime and must remain unique.
Start all six instances
Start every Redis process with its own configuration before running the cluster-creation command. Use Ubuntu service supervision (or another reliable process manager) so a process restarts after failure and starts in the intended order. Exact package service-unit names are release-specific, so verify the unit and paths supplied by your Ubuntu installation.
Check that each process is listening on its expected client port and that its data directory is writable. Do not bootstrap while one of the six instances is stopped, pointed at the wrong port, or reusing another node’s data directory.
Bootstrap the cluster with redis-cli
Once six empty, correctly configured instances are listening, run the following from a machine that can reach all six client ports:
redis-cli --cluster create
127.0.0.1:7000 127.0.0.1:7001 127.0.0.1:7002
127.0.0.1:7003 127.0.0.1:7004 127.0.0.1:7005
--cluster-replicas 1Replace the loopback addresses with the advertised, reachable addresses when the nodes are on different hosts. The --cluster-replicas 1 option asks Redis to create one replica for every master. Review the proposed slot and replica allocation, then answer yes.
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Redis assigns all 16,384 hash slots among the three masters and places one replica behind each master. A successful creation reports:
[OK] All 16384 slots coveredThat message means every hash slot has a serving master. It does not by itself prove that your firewall, persistence, client configuration, backups, or failure-domain placement are production-ready.
Local experimentation shortcut
Redis also publishes a utils/create-cluster helper. Its documented local flow is ./create-cluster start, followed by ./create-cluster create; stop or remove the test cluster with ./create-cluster stop or ./create-cluster clean. Use this utility for testing and experimentation. For a deployment that must survive reboots and failures, use explicit service supervision, durable paths, and your normal operational controls.
Validate membership, slots, and reachability
Inspect cluster state
redis-cli -p 7000 cluster info
redis-cli -p 7000 cluster nodes
redis-cli --cluster check 127.0.0.1:7000cluster info reports the node’s view of cluster health and slot coverage. cluster nodes shows node IDs, roles, addresses, slot ranges, and replica relationships. The --cluster check workflow checks the cluster through a node; use an address reachable from the machine running the command.
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Use a cluster-aware connection
redis-cli -c -p 7000The -c flag enables cluster mode in redis-cli. Application code must use a Redis Cluster-capable library that understands slot maps and redirections. A normal, non-cluster-aware client connected to one shard may receive a MOVED response when a requested key belongs to another shard.
Understand and fix MOVED errors
A MOVED response is a routing instruction, not necessarily a data-loss error. It tells the client that the key’s hash slot is served by another node. Connect with redis-cli -c or configure a cluster-aware library so the client follows the redirection and refreshes its slot map.
- If the error appears only with a basic client, replace that connection mode with a cluster-capable client.
- If a cluster-aware client cannot follow the address, check the node’s advertised address, DNS, routing, and firewall rules.
- If slot ownership is inconsistent, run
cluster nodesandredis-cli --cluster checkand resolve failed or uncovered nodes before sending application traffic.
Configure Ubuntu firewall rules correctly
Open both classes of traffic. Clients need the Redis client port; cluster members need the cluster-bus port from every other member. With the six-port example and no explicit cluster-port, that means allowing 7000–7005 for application traffic as appropriate and 17000–17005 between cluster nodes.
Do not open the bus to the public internet. Restrict it to the cluster’s private network or explicit member addresses. If you choose a custom cluster-port, document the resulting port map and allow that port instead of relying on the plus-10,000 convention.
Authentication and deployment choices
Manual Ubuntu services
Manual deployment gives you direct control over Ubuntu package and Redis version lifecycles, filesystem layout, service supervision, firewall policy, and upgrade timing. You must also build the surrounding controls: secret distribution, consistent authentication on every node and client, backups, monitoring, failure-domain placement, and scaling procedures.
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Juju-orchestrated deployment
Canonical’s Ubuntu tutorial presents Juju as an alternative for AWS, Google Cloud, Azure, and bare-metal environments. Juju can model the deployment, add authentication, and provide a repeatable orchestration workflow. Before choosing it, compare how it handles host count and failure domains, package/version lifecycle, network and firewall automation, secret management, persistence and backup integration, scaling, and observability.
Whichever method you use, configure authentication consistently on every Redis node and in every client. The appropriate ACL or password policy is an organizational security decision; there is no single policy specified by the cluster bootstrap command.
Scale and maintain the cluster
Add capacity
Redis Cluster scaling is a coordinated operation, not just starting another Redis process. Plan capacity headroom, choose the new node’s failure domain, start it with cluster mode and durable storage, then use the redis-cli --cluster workflows to add the node and assign slots.
Adding a master without moving slots leaves it idle. Use resharding to migrate selected hash slots from existing masters to the new shard, and monitor application latency and replication while the migration runs.
Replace or remove a node
Before removing a master, migrate its slots to healthy masters and confirm that its replica situation is understood. Before removing a replica, verify that the remaining failure tolerance is acceptable. The cluster command workflows support adding and removing nodes, migrating replicas, and resharding; perform them in a maintenance window with a tested rollback plan.
Test failover
Test that a replica can be promoted and that clients reconnect through their cluster-aware routing. Redis documents workflows for testing failover and performing a manual failover. Run these tests before an outage, record the observed client behavior, and verify that the replacement node advertises a reachable address.
Upgrade deliberately
Upgrade nodes one at a time or in another sequence that preserves the required replica coverage. Confirm compatibility, persistence, and client behavior before proceeding to the next node. Keep maintenance windows, backups, and a documented rollback path; do not treat a package upgrade as a substitute for a cluster-level upgrade plan.
Quick Recap
Persistence, recovery, and operational checks
- Keep each generated
nodes.confand append-only data set on durable storage. The node configuration file contains cluster identity and state and must not be casually deleted or edited. - Include persistence files and the generated cluster configuration in your recovery design. The Redis configuration enables persistence, but backup frequency, retention, encryption, and restore testing remain your responsibility.
- Monitor slot coverage, node availability, replication relationships, disk capacity, append-only growth, and client error rates.
- Document every node’s advertised address, client port, bus port, service definition, data path, and failure domain.
- After any network, firewall, or address change, rerun
cluster info,cluster nodes, andredis-cli --cluster checkfrom an application-reachable host.
Troubleshooting checklist
Cluster creation refuses to run
- Confirm all six instances are running and listening on the ports supplied to
redis-cli --cluster create. - Ensure the instances are empty cluster nodes, not reused data directories containing an old cluster identity.
- Check that every process can write its own data directory and generated
nodes.conf. - Verify that the addresses in the command are reachable from the machine performing bootstrap.
Nodes show as failed or never join
- Allow both client and cluster-bus traffic between every member.
- Check the bus calculation: without an explicit
cluster-port, it is client port plus 10,000. - Replace loopback or otherwise unreachable advertised addresses on multi-host deployments.
- Compare
cluster nodesoutput on more than one member to detect an inconsistent view.
Clients receive repeated MOVED responses
- Use
redis-cli -cor a Redis Cluster-capable library. - Check that the redirected address and port are routable from the client network.
- Run the cluster check and resolve missing slot coverage or failed nodes.
The cluster survives startup but loses data after a restart
- Confirm
appendonly yesis present in every instance configuration. - Verify that append-only files and
nodes.confare stored on persistent, writable storage. - Test restoration rather than assuming that enabled persistence alone is a backup.
Pre-production launch checklist
- Use at least three masters; use six nodes with one replica per master when failure tolerance is required.
- Give every instance a unique client port, isolated directory, and writable durable storage.
- Enable cluster mode, generated cluster configuration, a defined node timeout, and persistence on every node.
- Advertise addresses reachable by all members and application clients.
- Allow client and cluster-bus traffic only on the required private networks.
- Bootstrap with
--cluster-replicas 1and verify[OK] All 16384 slots covered. - Validate with cluster-aware clients,
cluster info,cluster nodes, andredis-cli --cluster check. - Test replica failover, resharding, node replacement, backups, restores, and upgrades before relying on the cluster.
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