adding db service (postgres database)

Hi there,

Im stuck again, trying to run the db. I'm doing everything exactly as in the video, but for some reason when I put the command docker-compose ps, it shows me this:

     Name                          Command               State                     Ports                  
----------------------------------------------------------------------------------------------------------------
example-voting-app_db_1       docker-entrypoint.sh postgres    Exit 1                                           
example-voting-app_redis_1    docker-entrypoint.sh redis ...   Up       6379/tcp                                
example-voting-app_result_1   docker-entrypoint.sh /bin/ ...   Up       0.0.0.0:5046->4000/tcp,:::5046->4000/tcp
example-voting-app_vote_1     gunicorn app:app -b 0.0.0. ...   Up       0.0.0.0:5045->80/tcp,:::5045->80/tcp    
example-voting-app_worker_1   /usr/local/bin/mvn-entrypo ...   Up              

I already checked if I have another postgres db on my system (I don't)...

any help?