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Deploy guide · Docker

Deploy Docker in minutes.

Connect the repository, Railpack builds it, the service gets a domain with TLS. Databases from templates, usage drawn per minute from a prepaid balance, everything on EU nodes.

Start with GitHubSee the CLI guide
terminal
$ npm i -g skiffly && skiffly login
$ cd my-repo && skiffly init            # repo with a Dockerfile
$ skiffly up
$ skiffly deploy --image ghcr.io/acme/api:1.4 --name api --port 8080

What Railpack detects

Railpack inspects the repository and picks the build for Docker; most projects need no configuration. A Dockerfile in the repository always wins.

  • Dockerfile in the repository root (or dockerfilePath)
  • or: any public / private registry image
  • EXPOSE is a hint; the port comes from the service settings
Builder
Dockerfile from the repository
Start command
CMD from the image (override in Settings → Deploy)

Derived by Railpack; override it in Settings → Deploy → Start command.

Port and $PORT

Skiffly injects PORT into every service and routes the public domain to it. Set the port in the service settings when your app listens on a fixed one; the default is 8080 for Docker, 8080 when nothing is set.

Listen on $PORT
CMD ["sh", "-c", "./server --port $PORT"]
PORT
8080
SKIFFLY_PUBLIC_DOMAIN
<service>.skiffly.cloud

From a terminal

Install the CLI, link the directory, deploy. skiffly up builds the pushed HEAD of the current branch and streams the build logs; skiffly domain gives the service a *.skiffly.cloud address.

Or describe it once

.skiffly/skiffly.ts declares the service, its databases and the references between them. skiffly config plan shows the diff, skiffly config apply makes it so. The API mirrors railway/iac.

Config as code
.skiffly/skiffly.ts
// .skiffly/skiffly.ts
import { defineSkiffly, github, postgres, project, service } from "@skiffly/config";

export default defineSkiffly(() => {
  const db = postgres("db");

  const web = service("api", {
    source: github("acme/api"),
    build: { builder: "DOCKERFILE", dockerfilePath: "Dockerfile" },
    port: 8080,
    healthcheck: "/",
    env: {
      DATABASE_URL: db.env.DATABASE_URL,
    },
  });

  return project("api", { resources: [web, db] });
});

Works with the templates you need

Deploy a database next to the Docker service and reference its variables: ${{Postgres.DATABASE_URL}} is wired on the private network, no public port.

Browse all templates
PostgreSQL 17The world's most advanced open-source relational database, with a persistent volume and DATABASE_URL pre-wired.Redis 7In-memory data store for caching, sessions and queues with append-only persistence.Nginx staticStatic files served by Nginx from a repository (Dockerfile build).

Docker on Skiffly: common questions

How do I set environment variables for Docker?
In the service's Variables tab, with skiffly variables set KEY=value, or in .skiffly/skiffly.ts. Reference other services with ${{Postgres.DATABASE_URL}} and environment-wide values with ${{shared.NAME}}. Secrets are encrypted at rest.
Can I change the build or start command?
Yes. Settings → Build → Build command overrides Railpack's build step; Settings → Deploy → Start command replaces the start command. A monorepo sets a root directory so the build runs inside it.
How do I add Postgres or Redis?
Deploy the template into the same environment. It arrives with a volume, generated credentials and a connection URL you reference from the Docker service. Connect from your laptop with skiffly connect postgres.
Do I get preview environments per pull request?
Turn on PR previews on the project: every pull request gets its own copy of the environment on its own domain, removed when the PR is merged or closed. Forks are ignored.
What does a small Docker app cost?
A 512 MB / 0.25 vCPU service runs at about $7.75 a month, drawn per minute from your balance. Add Postgres with 512 MB / 0.25 vCPU and a 10 GB volume for about $9 more. The free tier runs one 512 MB service with App Sleeping at no cost.
Can the Docker service sleep when idle?
Turn on App Sleeping: after about 10 minutes without a request it scales to zero and wakes on the next one (2–10 s). CPU and memory are not billed while asleep; the volume is.

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Start with GitHub