custom docker image is not running postgres

I am trying to create my own custom docker file for circleci v2. however, I am running into an issue where the postgres server is not running. I've run service postgresql start to no available.

the message I'm getting is:

psql: could not connect to server: Connection refused
    Is the server running locally and accepting
    connections on Unix domain socket "/var/run/postgresql/.s.PGSQL.5432"?

Dockerfile:

FROM ubuntu:16.04

ENV NODEJS_VERSION 6
ENV POSTGRESQL_VERSION 9.6

RUN apt-get update && apt-get -y install curl
RUN curl -sL https://deb.nodesource.com/setup_$NODEJS_VERSION.x | bash -
RUN apt-key adv --keyserver hkp://p80.pool.sks-keyservers.net:80 --recv-keys B97B0AFCAA1A47F044F244A07FCC7D46ACCC4CF8
RUN echo "deb http://apt.postgresql.org/pub/repos/apt/ precise-pgdg main" > /etc/apt/sources.list.d/pgdg.list
RUN apt-get update

RUN apt-get install -y \
  nodejs \
  make \
  git \
  g++ \
  python-software-properties \
  software-properties-common \
  postgresql-$POSTGRESQL_VERSION \
  postgresql-client-$POSTGRESQL_VERSION \
  postgresql-contrib-$POSTGRESQL_VERSION

RUN echo "host all all 0.0.0.0/0 md5" >> /etc/postgresql/$POSTGRESQL_VERSION/main/pg_hba.conf
RUN echo "listen_addresses='*'" >> /etc/postgresql/$POSTGRESQL_VERSION/main/postgresql.conf

USER postgres
RUN service postgresql start && \
  psql -c "create database pgdb;" && \
  psql -c "create role pgrole with login password 'pgrole'; grant all privileges on database pgdb to pgrole;"

See also:

• GitHub: https://github.com/jonathanong/docker-nodejs-postgres
• CircleCI: https://circleci.com/gh/jonathanong/docker-nodejs-postgres/tree/master

thanks

via Jonathan Ong