Declare the port a reverse proxy should send traffic to - #13
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Coolify generates Traefik routers from the compose file, but it reads `expose` to learn the backend port. With only a published `ports` mapping it emitted routers with no `loadbalancer.server.port`, so Traefik matched the host and then had nowhere to send the request: a 502 in front of a container that was running and healthy. `expose` is redundant for a plain `docker compose up`, where the published port already reaches the container. It is kept alongside `ports` rather than replacing it so `localhost:3000` keeps working, as the README documents. Also drops a comment on container_name that named the wrong cause. Coolify overrides that key with its own generated name, so it was never the reason the proxy could not reach the container.
Loa212
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Jul 30, 2026
Coolify decides the Traefik backend port by parsing it out of the domain string — `https://nudo.example.com:3000` — and emits the label naming that port only when it finds one. Without it the generated config has a router matching the hostname and no service behind it, so the proxy answers 502 in front of a container that started and passed its healthcheck. Nothing about the compose file changes that, which is what makes it worth writing down: `expose`, a published `ports` mapping and the predefined-network toggle all look like the thing to reach for and none of them are. Also corrects the comment on `expose` added in #13, which claimed Coolify reads that key to learn the port. It does not. The key is kept because stating the dashboard's port in the file is worth a line on its own, but the reason given for it was wrong.
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What changed
expose: ["3000"]alongside the existingportsmappingcontainer_namethat named the wrong causeWhy
Coolify generates Traefik routers from the compose file, but reads
exposeto learn the backend port. With only a publishedportsmapping, the generated labels contain routers:but no
traefik.http.services.….loadbalancer.server.port. Traefik matches the host and then has nowhere to send the request — a 502 in front of a container that is running and healthy (nudo is running — open the dashboard to finish setup dashboard=0.0.0.0:3000).exposeis redundant for a plaindocker compose up, where the published port already reaches the container. It is kept alongsideportsrather than replacing it solocalhost:3000keeps working, as the README documents.The
container_namecomment added in #12 named a cause that the generated compose disproves: Coolify overrides that key with its own name (nudo-hwi4754bcs2gz3o9ri2az61n-082055878291), so it was never why the proxy could not reach the container. Dropping the key is still right — nothing refers to the container by name — but the stated reason was wrong.Validation
NUDO_SECRET_KEY=validation-only docker compose config --quietexpose: ["3000"]andpublished: "3000", so neither path regressesgit diff --cached --check