Simplify Dockerfile

Dockerfile

@@ -1,19 +1,14 @@
 FROM ruby:2.5
 
-# fixes dpkg man page softlink error while installing postgresql-client [source: https://stackoverflow.com/a/52655008/5350059]
-RUN mkdir -p /usr/share/man/man1 && \
-    mkdir -p /usr/share/man/man7
+# Add yarn apt repository
+# https://classic.yarnpkg.com/en/docs/install#debian-stable
+RUN curl -sS https://dl.yarnpkg.com/debian/pubkey.gpg | apt-key add - && \
+    echo "deb https://dl.yarnpkg.com/debian/ stable main" > /etc/apt/sources.list.d/yarn.list
 
-# npm is not available in Debian repo so following official instruction [source: https://github.com/nodesource/distributions/blob/master/README.md#debinstall]
-RUN curl -sL https://deb.nodesource.com/setup_10.x -o nodesource_setup.sh && \
-    bash nodesource_setup.sh && \
-    rm -f nodesource_setup.sh
-
-# install packages
+# Install system packages
 RUN apt-get update && \
     apt-get install --no-install-recommends -y \
       build-essential \
-      curl \
       imagemagick \
       libarchive-dev \
       libffi-dev \
@@ -24,29 +19,21 @@ RUN apt-get update && \
       libxslt1-dev \
       locales \
       nodejs \
-      osmosis \
+      phantomjs \
       postgresql-client \
-      ruby-dev && \
+      ruby-dev \
+      yarn && \
     apt-get clean && \
     rm -rf /var/lib/apt/lists/*
 
-# install npm packages
-RUN npm install -g --unsafe-perm \
-      phantomjs-prebuilt \
-      yarn
-
 # Setup app location
 RUN mkdir -p /app
 WORKDIR /app
 
-# Install gems
-ADD Gemfile* /app/
+# Install Ruby packages
+ADD Gemfile Gemfile.lock /app/
 RUN bundle install
 
-# Setup local
-RUN sed -i -e 's/# en_GB.UTF-8 UTF-8/en_GB.UTF-8 UTF-8/' /etc/locale.gen && \
-    echo 'LANG="en_GB.UTF-8"'>/etc/default/locale && \
-    dpkg-reconfigure --frontend=noninteractive locales && \
-    update-locale LANG=en_GB.UTF-8
-
-ENV LANG en_GB.UTF-8
+# Install NodeJS packages
+ADD package.json yarn.lock /app/
+RUN yarn