add custom octoprint dockerfile; add link about cross-building images to buildscript

docker/octoprint/Dockerfile

@@ -1,5 +1,33 @@
-ARG VERSION=minimal
-FROM octoprint/octoprint:${VERSION}
+## Install OctoPrint and Plugins in venv
+FROM python:3 as build
 
-COPY plugins.txt /tmp/plugins.txt
-RUN pip install -r /tmp/plugins.txt
+ARG VERSION=1.7.2
+
+WORKDIR /opt
+COPY plugins.txt plugins.txt
+RUN python -m venv venv \
+ && venv/bin/pip install OctoPrint==${VERSION} \
+ && venv/bin/pip install -r plugins.txt
+
+## Runtime Image
+FROM python:3-slim as run
+
+WORKDIR /opt
+COPY --from=build /opt/venv venv
+COPY apt.txt apt.txt
+
+RUN apt update \
+ && apt install -y $(grep -vE "^\s*#" apt.txt  | tr "\n" " ") \
+ && apt clean
+
+RUN mkdir run cfg
+RUN groupadd octoprint --gid 1000 \
+ && useradd octoprint --uid 1000 --gid octoprint \
+ && usermod octoprint --append --groups dialout \
+ && chown -R octoprint:octoprint /opt/*
+
+ USER octoprint
+ EXPOSE 5000
+ VOLUME ["/opt/run", "/opt/cfg"]
+ ENTRYPOINT ["/opt/venv/bin/octoprint", "serve"]
+ CMD ["-b", "/opt/cfg"]

docker/octoprint/apt.txt

@@ -0,0 +1,5 @@
+# FilamentManager
+psycopg2
+
+# PrusaSlicerThumbnails
+libjpeg62-turbo

scripts/build-images.sh

@@ -1,5 +1,8 @@
 #!/bin/bash
 
+## https://www.stereolabs.com/docs/docker/building-arm-container-on-x86/
+## docker run --rm --privileged multiarch/qemu-user-static --reset -p yes
+
 set -e
 
 registry=${1}