From 571175eef5a4471fc8b2b674f03e72ae4e49fed4 Mon Sep 17 00:00:00 2001
From: Taka <taka@vm-linux-dev>
Date: Sat, 28 Nov 2020 19:39:24 +1100
Subject: [PATCH] Do a multi-stage build for Docker.

---
 Dockerfile | 57 ++++++++++++++++++++++++++++++++++++++----------------
 1 file changed, 40 insertions(+), 17 deletions(-)

diff --git a/Dockerfile b/Dockerfile
index 7c41ec6..ba6acdd 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,31 +1,30 @@
 # NOTE: Use the run-container.sh script to build and launch this container.
 
-FROM centos:8
+# We do a multi-stage build (requires Docker >= 17.05) to install everything, then copy it all
+# to the final target image.
+
+FROM centos:8 AS base
 
 # update packages
 RUN dnf -y upgrade-minimal
 
 # install Python
-RUN dnf install -y python36
+RUN dnf install -y python36 && pip3 install --upgrade pip
 
-# install Java
-RUN curl -s "https://download.java.net/java/GA/jdk15.0.1/51f4f36ad4ef43e39d0dfdbaf6549e32/9/GPL/openjdk-15.0.1_linux-x64_bin.tar.gz" \
-    | tar -C /usr/bin/ -xz
+# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 
-# install Firefox
-RUN dnf install -y wget bzip2 xorg-x11-server-Xvfb gtk3 dbus-glib && \
-    wget -qO- "https://download.mozilla.org/?product=firefox-latest-ssl&os=linux64&lang=en-US" \
-        | tar -C /usr/local/ -jx && \
-    ln -s /usr/local/firefox/firefox /usr/bin/firefox && \
-    echo "exclude=firefox" >>/etc/dnf/dnf.conf
+# NOTE: We install the Python dependencies into a temporary intermediate stage, then copy everything over
+# to the final image, because some modules (e.g. grpcio) need pre-requisites to be installed.
+# This saves us about 300 MB for the final image and, importantly, adding a requirement doesn't cause us
+# to re-install Java and Firefox below, when we start building the final image.
 
-# install geckodriver
-RUN url=$( curl -s https://api.github.com/repos/mozilla/geckodriver/releases/latest | grep -Poh 'https.*linux64\.tar\.gz(?!\.)' ) && \
-    curl -sL "$url" \
-        | tar -C /usr/bin/ -xz
+FROM base AS build
+
+# set up a virtualenv
+RUN python3 -m venv /opt/venv && pip3 install --upgrade pip
+ENV PATH="/opt/venv/bin:$PATH"
 
 # install the application requirements
-WORKDIR /app
 COPY requirements.txt requirements-dev.txt ./
 RUN pip3 install -r requirements.txt
 ARG CONTROL_TESTS_PORT
@@ -34,13 +33,37 @@ RUN if [ -n "$CONTROL_TESTS_PORT" ]; then \
     pip3 install -r requirements-dev.txt \
 ; fi
 
+# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+
+FROM base
+
+# install Java
+RUN url="https://download.java.net/java/GA/jdk15.0.1/51f4f36ad4ef43e39d0dfdbaf6549e32/9/GPL/openjdk-15.0.1_linux-x64_bin.tar.gz" ; \
+    curl -s "$url" | tar -C /usr/bin/ -xz
+
+# install Firefox
+RUN dnf install -y wget bzip2 xorg-x11-server-Xvfb gtk3 dbus-glib && \
+    wget -qO- "https://download.mozilla.org/?product=firefox-latest-ssl&os=linux64&lang=en-US" \
+        | tar -C /usr/local/ -jx && \
+    ln -s /usr/local/firefox/firefox /usr/bin/firefox && \
+    echo "exclude=firefox" >>/etc/dnf/dnf.conf
+
+# install geckodriver
+RUN url=$( curl -s https://api.github.com/repos/mozilla/geckodriver/releases/latest | grep -Poh 'https.*linux64\.tar\.gz(?!\.)' ) && \
+    curl -sL "$url" | tar -C /usr/bin/ -xz
+
 # clean up
 RUN dnf clean all
 
+# install the application requirements
+COPY --from=build /opt/venv /opt/venv
+ENV PATH="/opt/venv/bin:$PATH"
+
 # install the application
+WORKDIR /app
 COPY vasl_templates/webapp/ ./vasl_templates/webapp/
 COPY vassal-shim/release/vassal-shim.jar ./vassal-shim/release/
-COPY setup.py LICENSE.txt ./
+COPY setup.py requirements.txt requirements-dev.txt LICENSE.txt ./
 RUN pip3 install --editable .
 
 # install the config files