mongoid yaml combines environment variables for hosts

Question

I am new to rails and mongoid, I have mongoid.yml file that contains the entries as follows:

development:
  # Configure available database clients. (required)
  clients:
    # Defines the default client. (required)
    default:
      # Defines the name of the default database that Mongoid can connect to.
      # (required).
      database: mycollectionname
      # Provides the hosts the default client can connect to. Must be an array
      # of host:port pairs. (required)
      hosts:
        - localhost:27017

this works properly for development, however, in production, I'd like to specify the host from environment variables like ENV['OPENSHIFT_MONGODB_DB_HOST'] + ":" + ENV['OPENSHIFT_MONGODB_DB_PORT']

I've tried various ways such as this

    hosts:
      - <%= \"#{ENV['OPENSHIFT_MONGODB_HOST']}:#{ENV['OPENSHIFT_MONGODB_PORT']}\" %>

or

    hosts:
      - #{ENV['OPENSHIFT_MONGODB_HOST']:ENV['OPENSHIFT_MONGODB_PORT']}

etc, but none works

Answer 1

In yaml code, <%= %> is meant for you to insert ruby code, you can use Expression Substitution inside it to format your url

Expression substitution is a means of embedding the value of any Ruby expression into a string using #{ and }

Something like this will do:

<%= "#{ENV['OPENSHIFT_MONGODB_HOST']}:#{ENV['OPENSHIFT_MONGODB_PORT']}" %>

In my mongoid project with openshift, I am using its uri: field like this:

uri: <%= "#{ENV['OPENSHIFT_MONGODB_DB_URL']}#{ENV['OPENSHIFT_APP_NAME']}" %>

Please also pay attention to the indentation, it has to be accurate and it has to be space! Tab will cause problems too!