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+# Testing Redis Clustering
+
+The default development environment only runs under a single Redis instance.
+Some features (cross-cluster delete) do need a full cluster to test, so this
+document describes how to run such as cluster locally for testing.
+
+These instructions assume you've already gotten a normal development environment running.
+
+## Docker Compose
+
+The easiest way to run the Redis Cluster is to use Docker Compose.
+
+```
+docker compose -f deploy/dev.yml up -d --build
+```
+
+This will set up Redis in cluster mode and run two versions of Dotcom with nginx load balancing requests between them.
+Visit http://localhost:4001 to hit the load balancer.
+http://localhost:4002 and http://localhost:4003 will take you directly to either of the two nodes.
+
+You can even connect to individual Elixir nodes in order to run commands.
+Let's say you want to connect to dotcom2 (the one running at http://localhost:4003).
+
+```
+docker exec -it deploy-dotcom-2-1 iex --sname foobarbaz --cookie foobarbaz
+
+iex(foobarbaz@0b061394460f)1> node = :dotcom2@0b061394460f
+:dotcom2@0b061394460f
+iex(foobarbaz@0b061394460f)2> Node.connect(node)
+true
+iex(foobarbaz@0b061394460f)3> :rpc.call(node, Dotcom.Cache.Multilevel, :get, ["cms.repo|important-notices"])
+...
+```
+
+Note that the address (the @... part) will be different every time.
+
+
+## Running Redis Locally
+
+If you choose not to use Docker Compose, you'll still have to run Redis cluster.
+The easiest way to get it running is to download and compile it.
+
+```
+cd $HOME
+wget https://github.com/redis/redis/archive/7.2.4.tar.gz
+tar xvf 7.2.4.tar.gz
+cd redis-7.2.4
+make
+./utils/create-cluster/create-cluster start
+./utils/create-cluster/create-cluster create -f
+```
+
+Start the server with `iex -S mix phx.server`
+
+Then, visit the site at http://localhost:4001.
+
+When you're done with the cluster:
+
+```
+./utils/create-cluster/create-cluster stop
+cd $HOME
+rm 7.2.4.tar.gz
+rm -rf redis-7.2.4
+```
+