Improve build time with custom build image.

Dockerfile

@@ -1,31 +1,7 @@
 #
 # Stage 1, Prebuild
 #
-FROM microsoft/aspnetcore-build:2.0.3-jessie as builder
-
-# Install runtime dependencies
-RUN apt-get update \
- && apt-get install -y --no-install-recommends ca-certificates bzip2 libfontconfig \
- && apt-get clean \
- && rm -rf /var/lib/apt/lists/*
- 
- # Install official PhantomJS release
-RUN set -x  \
- && apt-get update \
- && apt-get install -y --no-install-recommends \
- && mkdir /srv/var \
- && mkdir /tmp/phantomjs \
-   # Download Phantom JS
- && curl -L https://bitbucket.org/ariya/phantomjs/downloads/phantomjs-2.1.1-linux-x86_64.tar.bz2 | tar -xj --strip-components=1 -C /tmp/phantomjs \
-   # Copy binaries only
- && mv /tmp/phantomjs/bin/phantomjs /usr/local/bin \
-   # Create symbol link
-   # Clean up
- && apt-get autoremove -y \
- && apt-get clean all \
- && rm -rf /tmp/* /var/lib/apt/lists/*
-
-RUN phantomjs --version
+FROM squidex/aspnetcore-build-phantomjs:2.0.3-jessie as builder
 
 COPY src/Squidex/package.json /tmp/package.json
 

libs/Dockerfile

@@ -0,0 +1,25 @@
+FROM microsoft/aspnetcore-build:2.0.3-jessie
+
+# Install runtime dependencies
+RUN apt-get update \
+ && apt-get install -y --no-install-recommends ca-certificates bzip2 libfontconfig \
+ && apt-get clean \
+ && rm -rf /var/lib/apt/lists/*
+ 
+ # Install official PhantomJS release
+RUN set -x  \
+ && apt-get update \
+ && apt-get install -y --no-install-recommends \
+ && mkdir /srv/var \
+ && mkdir /tmp/phantomjs \
+   # Download Phantom JS
+ && curl -L https://bitbucket.org/ariya/phantomjs/downloads/phantomjs-2.1.1-linux-x86_64.tar.bz2 | tar -xj --strip-components=1 -C /tmp/phantomjs \
+   # Copy binaries only
+ && mv /tmp/phantomjs/bin/phantomjs /usr/local/bin \
+   # Create symbol link
+   # Clean up
+ && apt-get autoremove -y \
+ && apt-get clean all \
+ && rm -rf /tmp/* /var/lib/apt/lists/*
+
+RUN phantomjs --version