Dockerinzing Play framework - docker

Question

I am developing a web app using play fraework2.6. I am trying to have java8, postgres and nginx in my dockerfile. Here's the docker file:
FROM ubuntu:14.04
#INSTALL
RUN \
echo "deb http://dl.bintray.com/sbt/debian /" | tee -a /etc/apt/sources.list.d/sbt.list \
&& sudo apt-get update -y --force-yes \
&& sudo apt-get install -y --force-yes sbt
RUN apt-get update && apt-get -y upgrade && apt-get -y install software-properties-common && add-apt-repository ppa:webupd8team/java -y && apt-get update
RUN (echo oracle-java8-installer shared/accepted-oracle-license-v1-1 select true | /usr/bin/debconf-set-selections) && apt-get install -y oracle-java8-installer oracle-java8-set-default
ENV JAVA_HOME /usr/lib/jvm/java-8-oracle
ENV PATH $JAVA_HOME/bin:$PATH
ENV SBT_OPTS="-Xmx2048M"
ENV SBT_OPTS="-XX:MaxPermSize=2048m"
# Add the PostgreSQL PGP key to verify their Debian packages.
# It should be the same key as https://www.postgresql.org/media/keys/ACCC4CF8.asc
RUN apt-key adv --keyserver hkp://p80.pool.sks-keyservers.net:80 --recv-keys B97B0AFCAA1A47F044F244A07FCC7D46ACCC4CF8
# Add PostgreSQL's repository. It contains the most recent stable release
# of PostgreSQL, ``9.3``.
RUN echo "deb http://apt.postgresql.org/pub/repos/apt/ precise-pgdg main" > /etc/apt/sources.list.d/pgdg.list
# Install ``python-software-properties``, ``software-properties-common`` and PostgreSQL 9.3
# There are some warnings (in red) that show up during the build. You can hide
# them by prefixing each apt-get statement with DEBIAN_FRONTEND=noninteractive
RUN apt-get update && apt-get install -y python-software-properties postgresql-9.3 postgresql-client-9.3 postgresql-contrib-9.3
# Install Nginx
RUN sudo apt-get install -y nginx
# RUN echo "\ndaemon off;" >> /etc/nginx/nginx.conf
# Note: The official Debian and Ubuntu images automatically ``apt-get clean``
# after each ``apt-get``
# Run the rest of the commands as the ``postgres`` user created by the ``postgres-9.3`` package when it was ``apt-get installed``
USER postgres
# Create a PostgreSQL role named ``docker`` with ``docker`` as the password and
# then create a database `docker` owned by the ``docker`` role.
# Note: here we use ``&&\`` to run commands one after the other - the ``\``
# allows the RUN command to span multiple lines.
RUN /etc/init.d/postgresql start &&\
psql --command "CREATE USER crm_play WITH SUPERUSER PASSWORD 'prod#123';" &&\
createdb -O crm_play crm_play
# Adjust PostgreSQL configuration so that remote connections to the
# database are possible.
RUN echo "host all all 0.0.0.0/0 md5" >> /etc/postgresql/9.3/main/pg_hba.conf
# And add ``listen_addresses`` to ``/etc/postgresql/9.3/main/postgresql.conf``
RUN echo "listen_addresses='*'" >> /etc/postgresql/9.3/main/postgresql.conf
# Expose the PostgreSQL port
EXPOSE 5432
# Add VOLUMEs to allow backup of config, logs and databases
VOLUME ["/etc/postgresql", "/var/log/postgresql", "/var/lib/postgresql"]
# Set the default command to run when starting the container
# CMD ["/usr/lib/postgresql/9.3/bin/postgres", "-D", "/var/lib/postgresql/9.3/main", "-c", "config_file=/etc/postgresql/9.3/main/postgresql.conf"]
WORKDIR /java/src/project
RUN sbt update
EXPOSE 9000
ENTRYPOINT ["sbt", "run"]
COPY . /java/src/project
First of all is this the correct way to do this. Also build takes too much of time to build. I am building like this:
docker build -t image:tag .
build downloads all dependencies in sbt and other dependencies mentioned in docker file. After that I run
docker run -it -p 9000:9000 image:tag
It again starts downloading all the dependencies. What I am doing wrong here?