One file, one deploy

The starting point was not an empty file. It was a full Codemoji production fly.toml — one that names a Fastify worker, a Redis queue, a SQLite-stream volume, and a Datadog agent. This single Phoenix release runs none of those, so the config is distilled: every stanza the Portal needs is kept, and every stanza for a service it does not run is dropped. Keeping a stanza for an absent service is not harmless — it points the platform at something that will never answer. Select a config family to see whether the Portal keeps it or the distillation drops it.

“Configured for prod” has two halves. The non-secret values live in the [env] block of fly.toml, committed in the open: the Portal’s own host, the listener gate, the pool size, the IPv6 trio. The two secrets are not in the file at all — SECRET_KEY_BASE and DATABASE_URL are set out of band with fly secrets set … -a echo-portal and listed by name with fly secrets list. The coupling is exact: every secret name a deploy provides must equal a name runtime.exs reads, or the boot raises. Select a value to see where it lives and what happens when it is missing.

In order: the distilled fly.toml stanza by stanza, with the de-Codemoji keep-versus-drop and the /health check coupled to the router’s health route; the [env]-versus-secret split and the raise-on-missing contract; and the rolling fly deploy, the machine lifecycle, the crash-loop suspend, and the release_command open decision.