fix: better Dockerfiles

Dockerfile

@@ -1,4 +1,4 @@
-FROM drogonframework/drogon
+FROM drogonframework/drogon AS installer
 
 ENV CORE_ROOT=$IROOT/core
 
@@ -10,4 +10,10 @@ WORKDIR $CORE_ROOT
 
 RUN ./build.sh
 
+FROM drogonframework/drogon
+
+COPY --from=installer /srv/core /srv/core
+
+EXPOSE 5000
+
 ENTRYPOINT ["/srv/core"]

Dockerfile.drogon

@@ -0,0 +1,27 @@
+FROM ubuntu:18.04
+
+RUN apt-get update -yqq && \
+    apt-get install -yqq --no-install-recommends software-properties-common && \
+    apt-get install -yqq --no-install-recommends sudo curl wget cmake locales git \
+    openssl libssl-dev libjsoncpp-dev uuid-dev zlib1g-dev postgresql-server-dev-all \
+    libmariadbclient-dev libsqlite3-dev gcc-8 g++-8 && \
+    locale-gen en_US.UTF-8
+
+ENV LANG en_US.UTF-8
+ENV LANGUAGE en_US:en
+ENV LC_ALL en_US.UTF-8
+
+ENV CC=gcc-8
+ENV CXX=g++-8
+ENV AR=gcc-ar-8
+ENV RANLIB=gcc-ranlib-8
+
+ENV IROOT=/install
+ENV DROGON_ROOT=$IROOT/drogon
+
+WORKDIR $IROOT
+ADD https://api.github.com/repos/an-tao/drogon/git/refs/heads/master version.json
+RUN git clone https://github.com/an-tao/drogon
+
+WORKDIR $DROGON_ROOT
+RUN ./build.sh