Services

A service is one container image, or the image built from your code, with the settings it runs with and its addresses. Most of what you run here is a service: a web app, an API, a worker, a cache. (Databases, computers, static sites and buckets are services or sit beside them, and have sections of their own.)

Where it comes from

• Your code, built from its Dockerfile with one command from your directory, your CI or your agent: deploying your code.
• A docker-compose file, a whole stack at once: docker-compose stacks.
• A published image, from Docker Hub or any registry: container images.
• A ready-made stack, an app with its database: one-click deploys.

Public or private

• Public: it gets an HTTPS address and sleeps when idle, unless you say otherwise. The next request wakes it.
• Private: no address on the internet, only name:port inside its project. Use this for workers and anything only your other services call. Private services always run.

While it runs

Every change to what runs is a deployment, with a log and a way back. It runs in a container with the memory and cores it's given, with its variables and secrets in its environment and, if it keeps data on disk, volumes. It can scale to more containers under load, and a preview of its project is a copy to try a change in.