---
title: Build and deploy settings
description: Every setting that controls how a service is built, started, checked, restarted and sized.
section: Services
order: 4
---

A service's settings decide how Dekka builds it, how it starts, how Dekka knows it's healthy and how much it may use. Open a service on the canvas and choose **Settings** to change them, then **Stage changes** and **Deploy changes** to apply them. Most of them can also come from a [`dekka.toml` or `dekka.json`](/docs/config-as-code) in the repository.

## Choose a builder

Services from GitHub have three builders under **Builder**.

- **Automatic** picks a build for you and works for common Node.js, Python and Go projects.
- **Buildpack** builds with a Railpack-style buildpack.
- **Dockerfile** builds the Dockerfile at **Dockerfile path**, which defaults to `Dockerfile` in the root directory.

If the automatic build guesses wrong, set the **Build command**, such as `npm run build`, and the **Start command**, such as `npm start` or `uvicorn app.main:app --host 0.0.0.0 --port $PORT`. Empty commands use what Dekka detects.

## Deploy only when certain files change

**Watch paths** lists globs, one per line, such as `apps/api/**` or `packages/shared/**/*.ts`. A push deploys the service only when at least one changed file matches one of them, and an empty list means any change deploys it. Globs are matched from the repository root, not the root directory, and a service can have up to 20.

## Run migrations before a release

The **Pre-deploy command**, such as `npm run migrate` or `python manage.py migrate --noinput`, runs once before the new release takes traffic.

## How does Dekka know my service is healthy?

For a web service, Dekka requests the **Health check path** on the new release and sends it traffic only after the path returns a 2xx. If that doesn't happen within the **Timeout**, which defaults to 30 seconds and can be up to 300, the deployment fails and the previous release keeps serving.

## What happens when my service crashes?

The **Restart policy** decides. **Restart when it crashes** is the default and tries up to the number of **Retries**, which defaults to 10. **Always restart** restarts the service whenever it exits, and **Never restart** leaves it stopped.

## Size a service

Under **Resources**, **Replicas** sets how many copies run, and **vCPU** and **Memory** set the limit for each copy. A new service gets 0.5 vCPU and 256 MiB. Each plan caps these per service.

| Plan | Memory | vCPU | Replicas |
| --- | --- | --- | --- |
| Free | 256 MiB | 0.5 | 1 |
| Starter | 512 MiB | 1 | 2 |
| Growth | 1024 MiB | 2 | 4 |

A service with a [volume](/docs/volumes) runs one replica.

## Sleep when idle

**Sleep when idle** stops a service when it has no traffic and wakes it on the next request, which can add a few seconds to that request. It's off by default.

## Networking settings

A web service's **Port** is the port it listens on, and Dekka sets `PORT` to the same value. **Public address** turns its `apps.dekka.cloud` address on or off. Your code must listen on `0.0.0.0` rather than `localhost`, or Dekka can't reach it.

## Setting names in the API and config files

In the API, these are fields of a service's `spec`. A [config file](/docs/config-as-code) uses the same names in its `build` and `runtime` sections.

- `build.strategy` is the **Builder**, one of `auto`, which is the default, `railpack` or `dockerfile`.
- `build.dockerfile_path` is the **Dockerfile path**, `Dockerfile` by default.
- `build.build_command` and `build.start_command` are the commands, detected when empty.
- `build.watch_paths` is a list of globs, empty by default.
- `build.pre_deploy_command` is the **Pre-deploy command**.
- `runtime.port` is the **Port**, `3000` by default.
- `runtime.health_check_path` is the **Health check path**, `/` by default.
- `runtime.health_check_timeout_seconds` is the health check **Timeout**, `30` by default.
- `runtime.memory_mib`, `runtime.vcpu` and `runtime.replicas` are the resources, `256`, `0.5` and `1` by default. vCPU goes in steps of 0.25.
- `runtime.restart_policy` is `on_failure`, which is the default, `always` or `never`, and `runtime.restart_max_retries` is the **Retries**, `10` by default.
- `runtime.cron_schedule` is the cron schedule, and `runtime.sleep_when_idle` is `false` by default.
- `source.root_dir` is the **Root directory**, `autodeploy` is **Deploy on push**, and `networking.public_domain` is **Public address**. A config file can't set these three.