Ship the store

After the Distributed chapter, KV replicates its data, catches up new nodes and forms its cluster with libcluster. But it still runs inside scripts that start their own nodes. This chapter ships it the way real services ship:

1. A release. KV becomes a Mix project built into a release. Every server runs the same build; what differs per server (node name, cookie, which nodes to cluster with) comes from environment variables read in config/runtime.exs at boot.

2. Containers. The release goes into a container image, and Docker Compose starts two KV nodes from it, each named by its environment.

3. Kubernetes. A Deployment runs KV pods that find each other through a headless Service and libcluster's Kubernetes.DNS strategy, with the cookie in a Secret.

Steps 2 and 3 are guides: they need Docker and a Kubernetes cluster, which the site's build doesn't have, so their commands are shown but weren't run.

Running these examples

Each step is a small Mix project. Its page shows every file and the shell commands that build and run it; the commands ran when the site was built, so the output is real. There is no Run button: browsers can't start programs.

To try one yourself, use Download project: the zip holds the project with the page as its README. Run the commands from the README in the project's directory. You need Elixir (which brings mix) and, for steps with dependencies, access to Hex.