Enable Postgis extension Postgres in Dockerfile - postgresql

Question

How can i enable the Postgis extension in a Dockerfile? The Postgres installation is already working
this is the command in Ubuntu:
sudo -u postgres psql -c "CREATE EXTENSION postgis;"
My Dockerfile:
# Set the base image to Ubuntu
FROM ubuntu:14.04
# Update the repository sources list
RUN apt-get update -y
################## BEGIN INSTALLATION ######################
# Postgres with Postgis
# Install wget
RUN apt-get install wget -y
# Setup Postgres repository
RUN wget --quiet -O - https://www.postgresql.org/media/keys/ACCC4CF8.asc | sudo apt-key add -
# Add Postgres repository
RUN sh -c "echo "deb http://apt.postgresql.org/pub/repos/apt/ trusty-pgdg main" >> /etc/apt/sources.list.d/postgresql.list"
# Update repository
RUN apt-get update -y
# Install Postgres with Postgis
RUN apt-get install postgresql-9.3-postgis-2.1 -y
# Change rights for start Postgresql
RUN chmod +x /etc/init.d/postgresql
# Start Postgresql
CMD service postgresql start && tail -F /var/lib/postgresql/data/serverlog

Answer 1

The solution for enable an extension
# Enable Postgis
RUN service postgresql start \
&& sudo -u postgres psql -c "CREATE EXTENSION postgis;"
RUN service postgresql stop

Answer 2

If you see other Dockerfiles using that psql -c command, like apache/marmotta Dockerfile, you will see lines like:
RUN service postgresql start \
&& psql --command "CREATE USER $DB_USER WITH PASSWORD '$DB_PASS';" \
&& psql --command "CREATE DATABASE $DB_NAME WITH OWNER $DB_USER;"
USER root
RUN service postgresql stop
In other words, you need to make sure the postgresql service is running for those commands to succeed.