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Issue deploying Rails app with capistrano

Dylan asked in Rails

Hello all. This is my first time ever trying to deploy a Rails application. I followed the guide to do so on Ubuntu 20.04, but I run the command bundle exec cap production deploy and it gets to the point of migrating to the production database, it throws this error.

00:31 deploy:migrating
      01 $HOME/.rbenv/bin/rbenv exec bundle exec rake db:migrate
      01 rake aborted!
      01 NoMethodError: Cannot load database configuration:
      01 undefined method `[]' for nil:NilClass
      01 (erb):16:in `<main>'
      01 /home/dylan/deployments/pride_skills/shared/bundle/ruby/2.7.0/gems/rai…
      01 /home/dylan/deployments/pride_skills/shared/bundle/ruby/2.7.0/gems/act…
      01 /home/dylan/deployments/pride_skills/shared/bundle/ruby/2.7.0/gems/rak…
      01 /home/dylan/.gem/ruby/2.7.0/gems/bundler-2.1.4/lib/bundler/cli/exec.rb…
      01 /home/dylan/.gem/ruby/2.7.0/gems/bundler-2.1.4/lib/bundler/cli/exec.rb…
      01 /home/dylan/.gem/ruby/2.7.0/gems/bundler-2.1.4/lib/bundler/cli/exec.rb…
      01 /home/dylan/.gem/ruby/2.7.0/gems/bundler-2.1.4/lib/bundler/cli.rb:476:…
      01 /home/dylan/.gem/ruby/2.7.0/gems/bundler-2.1.4/lib/bundler/vendor/thor…
      01 /home/dylan/.gem/ruby/2.7.0/gems/bundler-2.1.4/lib/bundler/vendor/thor…
      01 /home/dylan/.gem/ruby/2.7.0/gems/bundler-2.1.4/lib/bundler/vendor/thor…
      01 /home/dylan/.gem/ruby/2.7.0/gems/bundler-2.1.4/lib/bundler/cli.rb:30:i…
      01 /home/dylan/.gem/ruby/2.7.0/gems/bundler-2.1.4/lib/bundler/vendor/thor…
      01 /home/dylan/.gem/ruby/2.7.0/gems/bundler-2.1.4/lib/bundler/cli.rb:24:i…
      01 /home/dylan/.gem/ruby/2.7.0/gems/bundler-2.1.4/exe/bundle:46:in `block…
      01 /home/dylan/.gem/ruby/2.7.0/gems/bundler-2.1.4/lib/bundler/friendly_er…
      01 /home/dylan/.gem/ruby/2.7.0/gems/bundler-2.1.4/exe/bundle:34:in `<top …
      01 /home/dylan/.rbenv/versions/2.7.0/bin/bundle:23:in `load'
      01 /home/dylan/.rbenv/versions/2.7.0/bin/bundle:23:in `<main>'

Here is my database.yml:

# MySQL. Versions 5.5.8 and up are supported.
# Install the MySQL driver
#   gem install mysql2
# Ensure the MySQL gem is defined in your Gemfile
#   gem 'mysql2'
# And be sure to use new-style password hashing:
default: &default
  adapter: mysql2
  encoding: utf8mb4
  pool: <%= ENV.fetch("RAILS_MAX_THREADS") { 5 } %>
  username: <%= Rails.application.credentials.mysql[:username] %>
  password: <%= Rails.application.credentials.mysql[:password] %>
  socket: /var/run/mysqld/mysqld.sock

  <<: *default
  database: pride_skills_development

# Warning: The database defined as "test" will be erased and
# re-generated from your development database when you run "rake".
# Do not set this db to the same as development or production.
  <<: *default
  database: pride_skills_test

# As with config/credentials.yml, you never want to store sensitive information,
# like your database password, in your source code. If your source code is
# ever seen by anyone, they now have access to your database.
# Instead, provide the password as a unix environment variable when you boot
# the app. Read
# for a full rundown on how to provide these environment variables in a
# production deployment.
# On Heroku and other platform providers, you may have a full connection URL
# available as an environment variable. For example:
#   DATABASE_URL="mysql2://myuser:mypass@localhost/somedatabase"
# You can use this database configuration with:
#   production:
#     url: <%= ENV['DATABASE_URL'] %>
  <<: *default
  url: <%= ENV['DATABASE_URL'] %>

I've tried to search online to no avail. Any help would be massively appreciated.


There are a few possible things going on here. Is your rails master key saved as an env varaiable?


This is why the nil class error could be happening.

If you don't have the master key set then the following line won't work:


Try seeing if the master key ENV variable is set and just come back with any questions.

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