reduce image size

db/Dockerfile

@@ -1,15 +1,16 @@
 FROM postgres:12
 EXPOSE 5432
 
-RUN apt-get update 
-RUN apt-get -y install git libpq-dev postgresql-server-dev-12
-RUN apt-get -y install gcc make
-
 COPY init-count-bits.sh /docker-entrypoint-initdb.d/
 
-RUN git clone https://github.com/sldab/count-bits.git /opt/count-bits && \
+RUN apt-get update && \
+	apt-get -y install git libpq-dev postgresql-server-dev-12 gcc make && \
+	git clone https://github.com/sldab/count-bits.git /opt/count-bits && \
 	cd /opt/count-bits && \
 	make && \
 	sed -i.bak 's/create_functions: install/create_functions:/' Makefile && \
-	make install
+	make install && \
+	apt-get -y remove git libpq-dev postgresql-server-dev-12 && \
+	apt-get -y autoremove && \
+	apt-get -y clean