refactor docker to support arm32/arm64/amd64 all in one build

Dockerfile

@@ -1,20 +1,48 @@
-FROM node:6-alpine
-
-COPY . /cryptpad
-WORKDIR /cryptpad
-
-RUN apk add --no-cache git tini \
-   && npm install --production \
-   && npm install -g bower \
-   && bower install --allow-root
-
-EXPOSE 3000 3001
-
-VOLUME /cryptpad/datastore
-VOLUME /cryptpad/customize
+FROM node:6-stretch-slim
 
+# You want USE_SSL=true if not putting cryptpad behind a proxy
 ENV USE_SSL=false
 ENV STORAGE=\'./storage/file\'
 ENV LOG_TO_STDOUT=true
 
+# Persistent storage needs
+VOLUME /cryptpad/datastore
+VOLUME /cryptpad/customize
+VOLUME /cryptpad/blobstage
+VOLUME /cryptpad/pins
+VOLUME /cryptpad/tasks
+VOLUME /cryptpad/block
+
+# Required packages
+#   jq is a build only dependency, removed in cleanup stage
+RUN apt-get update \
+    && apt-get install -y --no-install-recommends \
+         git jq python
+
+# Install tini for faux init
+#   sleep 1 is to ensure overlay2 can catch up with the copy prior to running chmod
+COPY ./docker-install-tini.sh / 
+RUN chmod a+x /docker-install-tini.sh \
+    && sleep 1 \
+    && /docker-install-tini.sh \
+    && rm /docker-install-tini.sh
+
+# Cleanup apt
+RUN apt-get remove -y --purge jq python \
+    && apt-get auto-remove -y \
+    && apt-get clean \
+    && rm -rf /var/lib/apt/lists/*
+
+# Install cryptpad
+COPY . /cryptpad
+WORKDIR /cryptpad
+RUN npm install --production \
+    && npm install -g bower \
+    && bower install --allow-root
+
+# Unsafe / Safe ports
+EXPOSE 3000 3001
+
+# Run cryptpad on startup
 CMD ["/sbin/tini", "--", "/cryptpad/container-start.sh"]
+