Dockerfile: Populate a pip cache

Given the number of jobs in CI we have which use python and pip install
packages, we should do this once in the Dockerfile, in order to populate
the cache. We let each job continue to create and use the virtual
environments they need to facilitate making updates to these
environments easier.

Signed-off-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/tools/docker/Dockerfile b/tools/docker/Dockerfile
index bd02531..20c2b2a 100644
--- a/tools/docker/Dockerfile
+++ b/tools/docker/Dockerfile
@@ -265,6 +265,17 @@
 RUN useradd -m -U uboot
 USER uboot:uboot
 
+# Populate the cache for pip to use. Get these via wget as the
+# COPY / ADD directives don't work as we need them to.
+RUN wget -O /tmp/pytest-requirements.txt https://source.denx.de/u-boot/u-boot/-/raw/master/test/py/requirements.txt
+RUN wget -O /tmp/sphinx-requirements.txt https://source.denx.de/u-boot/u-boot/-/raw/master/doc/sphinx/requirements.txt
+RUN virtualenv -p /usr/bin/python3 /tmp/venv && \
+	. /tmp/venv/bin/activate && \
+	pip install -r /tmp/pytest-requirements.txt \
+		-r /tmp/sphinx-requirements.txt && \
+	deactivate && \
+	rm -rf /tmp/venv /tmp/pytest-requirements.txt /tmp/sphinx-requirements.txt
+
 # Create the buildman config file
 RUN /bin/echo -e "[toolchain]\nroot = /usr" > ~/.buildman
 RUN /bin/echo -e "kernelorg = /opt/gcc-12.2.0-nolibc/*" >> ~/.buildman