use python:3-slim-buster

docker/ci.Dockerfile

@@ -5,8 +5,6 @@ ENV TERM xterm
 # -- Install CI deps.
 RUN set -ex && \
     apt-get update -qq && \
-    apt-get upgrade -y -qq && \
-    apt-get install curl -y -qq --no-install-recommends && \
     apt-get install expect npm -y -qq >/dev/null && \
     apt-get clean -y -qq && \
     apt-get autoclean -y -qq && \
@@ -14,7 +12,6 @@ RUN set -ex && \
     npm install -g bats > /dev/null && \
     pip3 install bake-cli --upgrade --quiet > /dev/null && \
     apt remove --autoremove --purge -y curl && \
-    apt-get install expect npm -y -qq >/dev/null && \
     apt-get clean -y -qq && \
     apt-get autoclean -y -qq && \
     rm -fr /var/lib/apt/lists/*

docker/core.Dockerfile

@@ -1,28 +1,27 @@
-FROM ubuntu:19.04
+FROM python:3-slim-buster
 
 # Tell Ubuntu to not prompt during apt installs.
-ENV DEBIAN_FRONTEND 'noninteractive'
+ARG DEBIAN_FRONTEND='noninteractive'
+
+# -- Setup mirrors, for faster downloads (main sources can be *very* slow sometimes).
+RUN cat /etc/apt/sources.list
+COPY ./docker/scripts/use-mirrors.sh /opt/use-mirrors.sh
+RUN set -ex && \
+    /opt/use-mirrors.sh && \
+    rm -fr /opt/use-mirrors.sh
 
 # -- System dependencies + common utilities.
 RUN set -ex && \
     apt-get update -qq && \
     apt-get upgrade -y -qq && \
-    apt-get install curl python3 git python3-distutils  -y -qq >/dev/null && \
+    apt-get install curl git -y -qq --no-install-recommends >/dev/null && \
     apt-get clean -y -qq && \
     apt-get autoclean -y -qq
 
-# -- Install pip.
-RUN set -ex && curl -s --retry 3 https://bootstrap.pypa.io/get-pip.py > /tmp/get-pip.py && \
-    python3 /tmp/get-pip.py > /dev/null && rm -fr /tmp/get-pip.py
-
-# -- Install hconfig.
+# -- Install Pipenv.
 RUN set -ex && \
     pip3 install pipenv --quiet --no-cache 2>/dev/null
 
-# -- Clean up.
-RUN set -ex && \
-    apt-get clean -y -qq && apt-get autoremove -y -qq && apt-get autoclean -y -qq
-
 # -- Home directory.
 RUN set -ex && \
     mkdir /app

docker/scripts/use-mirrors.sh

@@ -1,6 +1,11 @@
 #!/usr/bin/env bash
 
 SOURCES_LIST='/etc/apt/sources.list'
-PREVIOUS_SOURCES=$(cat $SOURCES_LIST)
 
-perl -pe '/(http|https):\/\/(.*?)(\/|$)/ && s/$2/mirror.math.princeton.edu\/pub\//g' <<< "$PREVIOUS_SOURCES" > "$SOURCES_LIST"
+
+# deb http://snapshot.debian.org/archive/debian/20190910T000000Z buster main
+echo 'deb https://mirror.math.princeton.edu/pub/debian buster main' > ${SOURCES_LIST}
+# deb http://snapshot.debian.org/archive/debian-security/20190910T000000Z buster/updates main
+echo 'deb http://security.debian.org/debian-security buster/updates main' >> ${SOURCES_LIST}
+# deb http://snapshot.debian.org/archive/debian/20190910T000000Z buster-updates main
+echo 'deb http://deb.debian.org/debian buster-updates main' >> ${SOURCES_LIST}