[PATCH v2 1/3] docker: Rely on caching

[Stephen Finucane]

It seems less likely that tox and tox-pyenv will change than our
requirements. Split up the 'RUN' steps so we don't have to reinstall the
former every time the latter change.

Signed-off-by: Stephen Finucane <stephen at that.guru>
---
 tools/docker/Dockerfile | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git tools/docker/Dockerfile tools/docker/Dockerfile
index 35324b13..79408041 100644
--- tools/docker/Dockerfile
+++ tools/docker/Dockerfile
@@ -47,15 +47,14 @@ RUN pyenv latest install 2.7 && \
     pyenv latest install 3.5 && \
     pyenv latest install 3.6 && \
     pyenv latest install 3.7
-
 RUN pyenv global $(pyenv versions --bare | tac)
 
-COPY requirements-*.txt /tmp/
-RUN pip install tox tox-pyenv && \
-    pip install -r /tmp/requirements-dev.txt
+RUN pip install tox tox-pyenv
 
-# we deliberately leave the requirements files in tmp so we can
-# ping the user in entrypoint.sh if the change them!
+# we deliberately leave the requirements files in tmp so we can ping the user
+# in entrypoint.sh if they change
+COPY requirements-dev.txt requirements-test.txt /opt/
+RUN pip install -r /opt/requirements-dev.txt
 
 COPY tools/docker/entrypoint.sh /usr/local/bin/entrypoint.sh
 ENTRYPOINT ["/usr/local/bin/entrypoint.sh"]
-- 
2.21.0