# examples/starter/Dockerfile.example

## Naming

EXAMPLE — a component image. Copy, rename, replace. Named like the manifest it feeds and the resource it becomes:

```
Dockerfile.api   ->  image <cluster>-api  ->  image: in k8s/base/api.yaml
```

That image string is the ONLY thing connecting the three. Nothing checks it; a typo shows up as a pod stuck in ImagePullBackOff pulling from the public index, which reads like a network problem and is not one.

## COPY paths are relative to the build context

The overlay's Tiltfile runs from the overlay's own folder (rig's ctrl/Tiltfile includes it), so both paths in `docker_build` are relative to the overlay:

```
context='.'                  the overlay folder (or a subfolder, e.g. 'repodir/api')
dockerfile='Dockerfile.api'  relative to the overlay's Tiltfile too
```

Every COPY is resolved against the context, NOT against the Dockerfile's directory. With `context='.'` and the Dockerfile in a subfolder, a file sitting right beside it is still reached through that subfolder:

```
COPY docker/nginx.conf /etc/nginx/conf.d/default.conf     # correct, Dockerfile in docker/
COPY nginx.conf        /etc/nginx/conf.d/default.conf     # fails — no such file in the context
```

Nothing warns you. The build just cannot find a file that is visibly there.

Before overlays, rig's own ctrl/Tiltfile built with `context='..'` (the repository root) and the Dockerfile in ctrl/, which is the same trap one level up.

## Dependency layer

Dependencies first, in their own layer: they change far less often than the code, so a source edit does not reinstall them on every rebuild.

## live_update

The sync in the Tiltfile's `docker_build` must land where this image expects it:

```
live_update=[sync('api', '/app/api')]
```

matches `COPY api/ ./api/` with `WORKDIR /app`. If the two disagree, Tilt syncs into a path nothing reads and the container keeps serving the built copy — edits appear to do nothing, with no error anywhere.