If you plan to run several Livebook instances behind a load balancer, you need to enable clustering via the `LIVEBOOK_CLUSTER` environment variable. In addition you must set `LIVEBOOK_SECRET_KEY_BASE` and `LIVEBOOK_COOKIE` to different random values (use `openssl rand -base64 48` to generate said values).
Depending on the clustering strategy of your choice, you must set additional environment variables, oftentimes, at runtime. When using the Livebook Docker image, you can create a file at `/app/user/env.sh` that exports the necessary environment variables. This file is invoked right before booting Livebook.
You may set `LIVEBOOK_CLUSTER` to one of the following values.
Detects the hosting platform and automatically sets up a cluster using DNS configuration. Currently the only supported platform is Fly.io (and Kubernetes when using Livebook Teams).