Fix fluentd-gcp Dockerfile to reduce image size

cluster/addons/fluentd-gcp/fluentd-gcp-image/Dockerfile

@@ -30,27 +30,29 @@ ENV DEBIAN_FRONTEND noninteractive
 # Install build tools
 RUN apt-get -qq update && \
     apt-get install -y -qq curl ca-certificates gcc make bash sudo && \
-    apt-get install -y -qq --reinstall lsb-base lsb-release
-
-# Install logging agent and required gems
-RUN /usr/bin/curl -sSL https://toolbelt.treasuredata.com/sh/install-ubuntu-xenial-td-agent2.sh | sh && \
+    apt-get install -y -qq --reinstall lsb-base lsb-release && \
+    # Install logging agent and required gems
+    /usr/bin/curl -sSL https://toolbelt.treasuredata.com/sh/install-ubuntu-xenial-td-agent2.sh | sh && \
     sed -i -e "s/USER=td-agent/USER=root/" -e "s/GROUP=td-agent/GROUP=root/" /etc/init.d/td-agent && \
     td-agent-gem install --no-document fluent-plugin-record-reformer -v 0.8.2 && \
     td-agent-gem install --no-document fluent-plugin-systemd -v 0.0.5 && \
-    td-agent-gem install --no-document fluent-plugin-google-cloud -v 0.5.2
-
-# Remove build tools
-RUN apt-get remove -y -qq gcc make && \
+    td-agent-gem install --no-document fluent-plugin-google-cloud -v 0.5.2 && \
+    # Remove build tools
+    apt-get remove -y -qq gcc make && \
     apt-get autoremove -y -qq && \
-    apt-get clean -qq
-
-# Remove unnecessary files
-RUN rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/*
+    apt-get clean -qq && \
+    # Remove unnecessary files
+    rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/* \
+        /opt/td-agent/embedded/share/doc \
+        /opt/td-agent/embedded/share/gtk-doc \
+        /opt/td-agent/embedded/lib/postgresql \
+        /opt/td-agent/embedded/bin/postgres \
+        /opt/td-agent/embedded/share/postgresql \
+        /etc/td-agent/td-agent.conf
 
 # Copy the Fluentd configuration files for logging Docker container logs.
 # Either configuration file can be used by specifying `-c <file>` as a command
 # line argument.
-RUN rm /etc/td-agent/td-agent.conf
 COPY google-fluentd.conf /etc/td-agent/google-fluentd.conf
 COPY google-fluentd-journal.conf /etc/td-agent/google-fluentd-journal.conf