title: How to create postgres extension inside the container?
body: <p>I have to install <code>hstore</code> to my docker postgres<br>
  Here is my ordinary command in the shell to execute my need<br></p>
  
  <pre><code>psql -d template1 -c 'create extension hstore';
  </code></pre>
  
  <p>If I remove that line my container, it works, but I have execute <code>hstore</code> installation by myself and I have to tell everyone in my project to do so which is not a good practice</p>
  
  <p>Here is my <code>yml file</code></p>
  
  <pre><code>  postgres:
      build:
        context: .
        dockerfile: dockerfiles/devdb.dockerfile
      environment:
        POSTGRES_USER: uih
        POSTGRES_PASSWORD: uIhbod!
        POSTGRES_DB: uih_portal
      ports:
          - "5433:5432"
  </code></pre>
  
  <p>Here is my docker file <code>devdb.dockerfile</code><br></p>
  
  <pre><code>FROM postgres:9.5
  
  RUN mkdir -p /var/lib/postgresql-static/data
  ENV PGDATA /var/lib/postgresql-static/data
  
  # psql -d template1 -c 'create extension hstore;'
  CMD ["psql", "-d", "template1", "-c", "'create extension hstore;'"]
  
  RUN echo "hstore extension installed"
  </code></pre>
  
  <p>After build I can not get it run<br></p>
  
  <pre><code>$ docker-compose up postgres
  Recreating uihportal_postgres_1
  Attaching to uihportal_postgres_1
  postgres_1       | psql: could not connect to server: No such file or directory
  postgres_1       |      Is the server running locally and accepting
  postgres_1       |      connections on Unix domain socket "/var/run/postgresql/.s.PGSQL.5432"?
  uihportal_postgres_1 exited with code 2
  </code></pre>
  
  <p><strong>Question:</strong></p>
  
  <p>How to install <code>hstore</code> from the dockerfile?<br>
  I want to make an image and re-use it for the entire project for my team</p>