pre-warm matplotlib font cache

IV/Dockerfile

@@ -7,3 +7,7 @@ RUN apt-get update && \
     python3-pygments python3-geopandas \
     latexmk make \
     docker.io
+
+COPY layer2img.py /tmp/layer2img.py
+RUN python3 /tmp/layer2img.py -o /tmp/foo.pdf
+RUN rm /tmp/layer2img.py

IV/in-container

@@ -12,7 +12,7 @@ set -euo pipefail
 
 NAME=wm-mj-build
 if [[ -z "$(docker images -q --filter "reference=$NAME")" ]]; then
-    docker build -t "$NAME" - < Dockerfile
+    docker build -t "$NAME" .
 fi
 
 exec docker run -ti --rm \