rig major updates

rig/examples/starter/Dockerfile.example

@@ -0,0 +1,24 @@
+# EXAMPLE component image. Copy, rename, replace:
+#   Dockerfile.api  ->  image <cluster>-api  ->  image: in k8s/base/api.yaml
+# COPY paths are relative to the build context the overlay's Tiltfile names (context='.').
+# Notes: rig's docs/notes/Dockerfile.example.md
+
+FROM python:3.12-slim
+
+WORKDIR /app
+
+# Dependencies first, in their own layer, so a source edit does not reinstall them.
+COPY api/requirements.txt ./
+RUN pip install --no-cache-dir -r requirements.txt
+
+# Context-relative — see above.
+COPY api/ ./api/
+
+# Match this with the containerPort in the manifest and the target of the
+# Service in front of it.
+EXPOSE 8000
+
+CMD ["python", "-m", "api"]
+
+# live_update: the Tiltfile's sync('api', '/app/api') must match COPY api/ + WORKDIR /app,
+# or edits silently do nothing.