---
title: Hosting
description: A Service builds your repository, ships as a Release in waves, serves on its routes, and idles to zero when nothing calls it.
type: tutorial
product: hosting
summary: What a Service is, what you set on it, and the path from a push to a request.
updated: 2026-10-01
order: 0
---

<Callout tone="note" title="Today this runs on the management API">
Hosting is served through the management API: the [Hosting quickstart](/docs/hosting/quickstart) shows the project, service, deploy and status calls. The collections named on this page (`services`, `source_links`, `releases`, `service_rollouts`, `routes`, `previews`) describe the product's resource model; their commands are not the way to use Hosting at api.sylphx.com.
</Callout>

A Service is one deployable workload. It has a source — a repository, or an
image by digest — and everything after that is the platform's: the build, the
Release, the rollout, the routes, and the scaling down to zero when nobody is
calling.

## The parts you set

<PropertyTable
	properties={[
		{
			name: 'source',
			type: 'ServiceSource',
			description: 'What the Service runs: a SourceLink repository to build from, or an image by digest to run as-is. Required.',
		},
		{
			name: 'command',
			type: 'string',
			description: 'Overrides the image’s command.',
		},
		{
			name: 'port',
			type: 'int32',
			description: 'The port the application listens on. The public edge stays 443.',
		},
		{
			name: 'exposure',
			type: 'ServiceExposure',
			description: 'Who can reach the Service. Public by default; internal keeps it off the public edge.',
		},
		{
			name: 'size',
			type: 'InstanceSize',
			description: 'The size of each instance: nano, micro, small, standard, large, xlarge or xxlarge. The plan’s size by default.',
		},
		{
			name: 'scaling',
			type: 'ServiceScaling',
			description: 'How many instances to keep, and how many at most.',
		},
		{
			name: 'health',
			type: 'ServiceHealth',
			description: 'How an instance is probed, and how long a new one may take to pass.',
		},
		{
			name: 'env',
			type: 'map',
			description: 'Plain environment variables. Nothing secret belongs here.',
		},
		{
			name: 'secret_env',
			type: 'map',
			description: 'Environment variables bound to Secrets: variable name to Secret name. The value never enters the spec.',
		},
		{
			name: 'regions',
			type: 'string[]',
			description: 'Regions to run in; the project’s home region by default.',
		},
	]}
/>

## From a push to a request

1. **Source.** A [SourceLink](/docs/api/source_links) links the project to one
   repository through a forge connection. Source is read at an exact commit,
   with a token narrowed to that repository; a webhook only says that
   something changed.
2. **Build.** The build turns the source into an image — a release candidate
   identified by its digest.
3. **Release.** A [Release](/docs/api/releases) is the immutable desired state
   of an environment's workloads. Writing a newer one supersedes the live one;
   a rollback is a new Release naming older digests.
4. **Rollout.** A [Rollout](/docs/api/service_rollouts) moves one Service
   generation to its Release in waves — a canary Cell, one Cell, one region,
   all — and no wave advances without fresh recorded evidence.
5. **Routes.** A [Route](/docs/api/routes) sends one exact host and path
   prefix to one backend. Every destination has its own Route; a wildcard
   grants no authority.
6. **Previews.** A [Preview](/docs/api/previews) is a pull request's own
   deployment of the Service, built and torn down by the same Git flow.

## It idles to zero

`scaling.min_instances` defaults to zero, which means no traffic means no
instances: the first request after a quiet spell wakes the Service rather than
failing. There is nothing to start, and nothing to shut down. Raise the floor
only where a cold start is worse than the idle cost.

<KeyValue
	items={[
		{ key: 'Name', value: 'orgs/{org}/projects/{project}/envs/{env}/services/{service}', mono: true },
		{ key: 'Id', value: 'svc_<location><ulid>', mono: true },
	]}
/>

A Service's name is a path, and the same path works in the API, the CLI and
the console. `hosting:read` covers the reads; everything that changes the
Service needs `hosting:write`.

<RelatedDocs
	links={[
		{
			href: '/docs/hosting/quickstart',
			label: 'Quickstart',
			description: 'Connect a repository, create the Service, and roll it out.',
		},
		{
			href: '/docs/api/services',
			label: 'The services collection',
			description: 'Every method, its scope and its examples.',
		},
		{
			href: '/docs/hosting/configuration',
			label: 'Configuration',
			description: 'Environment, secrets, sizes, scaling and regions.',
		},
	]}
/>