Use uv to install tools in tagger image (DataDog#23221)

* Use pipx to install ddev and awscli in tagger image

* Use pipx venv copy instead of building sdist tarball

* Use ARG for base image so bumping requires a single line change

* Switch to uv for zero-maintenance Python version management

* Revert HATCH_VCS_PRETEND_VERSION attempt, writable copy is required

Author: AAraKKe

.gitlab/tagger/Dockerfile

@@ -1,12 +1,8 @@
-# Use a separate image to build ddev from source so the final image doesn't need git
-FROM registry.ddbuild.io/images/mirror/python:3.13.0 AS ddev-python
-COPY . /home
-RUN python -m pip install build
-RUN python -m build -s ./home/ddev
-RUN mv ./home/ddev/dist/*.tar.gz ddev.tar.gz
-
 FROM registry.ddbuild.io/images/mirror/ubuntu:25.04
 
+# Get uv — manages Python installations on demand, no system Python pinning needed
+COPY --from=ghcr.io/astral-sh/uv:latest /uv /usr/local/bin/uv
+
 # Update sources and install required packages
 RUN apt-get update \
  && apt-get -y install --no-install-recommends \
@@ -41,12 +37,14 @@ COPY --from=registry.ddbuild.io/dd-octo-sts:v1.10.4@sha256:20edc79b3fc3f9cd58eb0
 # Locales are required to be set to use click
 ENV LC_ALL=C.UTF-8
 ENV LANG=C.UTF-8
+ENV UV_TOOL_BIN_DIR=/usr/local/bin
 
-# Copy in ddev.tar.gz from the other image
-COPY --from=ddev-python ddev.tar.gz /
-
-# Install pip and ddev for release tagging
-# Install awscli for access to the key used for signing in integrations-extras and marketplace
-RUN curl -sSL https://bootstrap.pypa.io/get-pip.py | python3 - --break-system-packages \
- && pip3 install --no-cache-dir --break-system-packages awscli==1.29.7 \
- && pip3 install --no-cache-dir --break-system-packages ddev.tar.gz
+# Mount the build context without adding it to the image.
+# Copy to a writable location because hatch-vcs writes src/ddev/_version.py during build,
+# which fails on the read-only bind mount. Both the copy and removal are in one RUN
+# so the source never lands in the final image.
+RUN --mount=type=bind,source=.,target=/src \
+    cp -r /src /tmp/repo \
+ && uv tool install /tmp/repo/ddev \
+ && uv tool install 'awscli==1.29.7' \
+ && rm -rf /tmp/repo