Reduce Docker image size

Dockerfile

@@ -1,15 +1,32 @@
-FROM node:10
+FROM node:10-stretch-slim AS build
 
 WORKDIR /app
-RUN \
-  apt-get -y update && \
-  apt-get -y install dumb-init libopencv-dev && \
-  rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/*
+RUN apt-get -y update \
+  && apt-get -y install libopencv-dev \
+  && rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/*
 
 COPY package.json package.json
-RUN mkdir tmp && npm install
+RUN npm install && npm cache clean --force
 
-COPY illuminati.js illuminati.js
+FROM node:10-stretch-slim
+
+RUN apt-get -y update \
+  && apt-get -y install \
+  dumb-init \
+  libopencv-contrib2.4v5 \
+  libopencv-gpu2.4v5 \
+  libopencv-ocl2.4v5 \
+  libopencv-stitching2.4v5 \
+  libopencv-superres2.4v5 \
+  libopencv-ts2.4v5 \
+  libopencv-videostab2.4v5 \
+  && rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/*
+
+COPY --from=build /app/node_modules /app/node_modules
+COPY illuminati.js /app/illuminati.js
+RUN mkdir /app/tmp
+
+WORKDIR /app
 ENTRYPOINT ["/usr/bin/dumb-init", "--"]
 CMD ["node", "illuminati.js"]
 EXPOSE 3000