Installation : problème de connection postgres

Bonjour, je suis en train d'installer decidim en suivant la procédure décrite ici : https://github.com/Platoniq/decidim-install/blob/master/decidim-bionic.md Les choses se déroulent (à peu près) bien, jusqu'à ce que "decidim devrait pouvoir commencer à marcher", et l'instruction suivante : $ bin/rails db:create RAILS_ENV=production qui me donne la sortie suivante : === début sortie could not connect to server: Connection refused Is the server running on host "localhost" (::1) and accepting TCP/IP connections on port 5432? could not connect to server: Connection refused Is the server running on host "localhost" (127.0.0.1) and accepting TCP/IP connections on port 5432? Couldn't create 'decidim_prod' database. Please check your configuration. rails aborted! PG::ConnectionBad: could not connect to server: Connection refused Is the server running on host "localhost" (::1) and accepting TCP/IP connections on port 5432? could not connect to server: Connection refused Is the server running on host "localhost" (127.0.0.1) and accepting TCP/IP connections on port 5432? bin/rails:4:in `' Tasks: TOP => db:create (See full trace by running task with --trace) could not connect to server: Connection refused Is the server running on host "localhost" (::1) and accepting TCP/IP connections on port 5432? could not connect to server: Connection refused Is the server running on host "localhost" (127.0.0.1) and accepting TCP/IP connections on port 5432? Couldn't create 'decidim_prod' database. Please check your configuration. rails aborted! PG::ConnectionBad: could not connect to server: Connection refused Is the server running on host "localhost" (::1) and accepting TCP/IP connections on port 5432? could not connect to server: Connection refused Is the server running on host "localhost" (127.0.0.1) and accepting TCP/IP connections on port 5432? bin/rails:4:in `' Tasks: TOP => db:create (See full trace by running task with --trace) === fin sortie Je dois dire que je n'ai jamais ni installé ni même utilisé postgres. J'ai mis en oeuvre différentes suggestions trouvées ici et là sur le web, mais sans succès. Auriez-vous des suggestions, svp ? J'installe sur un serveur distant (chez un hébergeur), créé pour l'occasion, et équipé avec ubuntu 18.04. La version de PostgreSQL est la 10.9. Merci pour votre aide ! Jean-Philippe