Domains and ports

Add a domain to the app on its Network tab, point a DNS record at the server, and Cubeship gets the certificate. Under an sslip.io instance the name already resolves, so it works the moment it is added.

A name carries a port

An app is served at any number of names, and each name has its own port. One image exposing an API on 8080 and an admin panel on 9090 is two names:

The proxy gets one router and one service per name, which is what makes the ports independent.

A host is unique across the instance, not per app: the proxy routes by host and nothing else, and two apps claiming one name would give it two answers.

Ports

Port 0 means "read it from the image", and it is the normal answer. EXPOSE ends up in an image's config, so the deploy reads it there — the Dockerfile is not always around, and never is for an image somebody else built. An image exposing nothing, or several, falls back to 8080; a number on the name is you overruling that.

The image is inspected inside the deploy, because that is the first moment it certainly exists. So a port cannot be detected when the app is configured, and the field is always offered.

The suggested name

Every app is offered a name under the instance's own domain:

<app>.<environment>.<project>.<instance domain>
api.production.shop.203-0-113-7.sslip.io

It is a suggestion, never assigned — plenty of apps should not answer on the internet. Under an sslip.io address every name resolves to the same host with nothing registered anywhere, so it works at once. Under a real domain it needs a wildcard record, or a DNS provider that writes the instance's records.

Certificates

Each name is its own Let's Encrypt certificate, issued by the proxy over TLS-ALPN on the instance's own :443 and renewed for you. The Certificates screen says which name has one, which is waiting, and why.

Two things worth knowing:

• Let's Encrypt rate-limits per registered domain, and sslip.io is one registered domain shared with everyone using it. A busy week can hit the limit; a domain of your own does not share its allowance.
• A name that failed once is asked for again every half hour for as long as it is pending. A record written a minute late is not a name lost for the life of the instance.

A change takes a redeploy

A container keeps the labels it was created with, so adding or removing a name, or changing a port, changes nothing until the app is redeployed. The screen says so.

From the CLI

cubeship app get shop/api          # every name, with its port

Names are added and removed on the dashboard; the API has POST /apps/{ref}/domains, PATCH …/domains/{id} for the port and DELETE …/domains/{id}.