Install project deps before copying src for faster builds

Author: schloerke

Dockerfile

@@ -4,7 +4,10 @@ RUN apt-get update && apt-get install -y make
 
 WORKDIR /sdk
 
-COPY Makefile pyproject.toml vars.mk ./
+COPY Makefile pyproject.toml vars.mk uv.lock ./
+
+# Run before `COPY src src` to cache dependencies for faster iterative builds
+RUN --mount=type=cache,mode=0755,target=/root/.cache/pip make docker-deps
 
 COPY .git .git
 COPY src src

Makefile

@@ -2,7 +2,7 @@ include vars.mk
 
 .DEFAULT_GOAL := all
 
-.PHONY: build clean cov default dev docs ensure-uv fmt fix install it lint test uninstall version help
+.PHONY: build clean cov default dev docker-deps docs ensure-uv fmt fix install it lint test uninstall version help
 
 all: dev test lint build
 
@@ -32,6 +32,12 @@ cov-xml: dev
 dev: ensure-uv
 	$(UV) pip install -e .
 
+docker-deps: ensure-uv
+	# Sync given the `uv.lock` file
+	# --frozen : assert that the lock file exists
+	# --no-install-project : do not install the project itself, but install its dependencies
+	$(UV) sync --frozen --no-install-project
+
 docs: ensure-uv
 	$(MAKE) -C ./docs