Rails server starts but AR Connection not established for reading role

Question

A confusion with the pg gem compiled against some previous version of homebrew, leading to the reinstallation of postgresql, led to uninstalling and reinstalling the pg gem. gem uninstall pg gem install pg

Subsequently, the rails console and server can be activated, and while the former can be used, the server returns an error when previously this had never been seen. Needless to say, nothing else changed in the application in the meantime.

Processing by HomeController#hello as HTML
Completed 500 Internal Server Error in 5ms (Allocations: 3461)

ActiveRecord::ConnectionNotEstablished (No connection pool for 'ActiveRecord::Base' found for the 'reading' role.):

pointing to an issue with config/database.yml There, the default suggestion fro Rails 7 indicates:

# On macOS with Homebrew:
#   gem install pg -- --with-pg-config=/usr/local/bin/pg_config

but /usr/local is an empty directory and the install command with those options fails

*** extconf.rb failed ***
Could not create Makefile due to some reason, probably lack of necessary libraries and/or headers.  Check the mkmf.log file for more details.  You may
need configuration options.

the simple gem install command yields:

gem install pg
Building native extensions. This could take a while...
Successfully installed pg-1.4.3
Parsing documentation for pg-1.4.3
Installing ri documentation for pg-1.4.3
Done installing documentation for pg after 0 seconds
1 gem installed

database.yml is configured by stock rails installation:

default: &default
  adapter: postgresql
  encoding: unicode
  # https://guides.rubyonrails.org/configuring.html#database-pooling
  pool: <%= ENV.fetch("RAILS_MAX_THREADS") { 5 } %>

development:
  primary:
    <<: *default
    database: mrt_development
    username: deploy_root
    password: [...]
  primary_replica:
    <<: *default
    database: mrkt_test
    username: deploy_readonly
    password: password
    replica: true

The [rails guide][1] provides no indications as to 'reading' roles.

What should be done to get a proper connection running? [1]: https://guides.rubyonrails.org/configuring.html#database-pooling

Update
Interesting behaviour observed: a deployment has led to the same error being generated on the remote server.

Rails server starts but AR Connection not established for reading role

0 Answers