Production environment configuration in Ruby on Rails - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ component_behavior

intermediate

What is the effect of setting config.cache_classes = true in production?

In a Rails production environment configuration, what does setting config.cache_classes = true do?

A It reloads application classes on every request, slowing down response time.

B It enables verbose logging of class loading for debugging purposes.

C It caches application classes so they are loaded once, improving performance.

D It disables class loading entirely, causing errors when classes are referenced.

💡 Hint

Think about how caching classes affects speed and memory in production.

Setting config.cache_classes = true in production tells Rails to load application classes once and cache them. This avoids reloading classes on every request, which improves performance.

📝 Syntax

intermediate

Identify the correct syntax to enable serving static files in production

Which of the following lines correctly enables serving static files in a Rails production environment configuration file?

A config.public_file_server.enabled = ENV['RAILS_SERVE_STATIC_FILES'].present?

B config.public_file_server.enabled == true

C config.public_file_server.enabled = true if ENV['RAILS_SERVE_STATIC_FILES']

D config.public_file_server.enabled = ENV['RAILS_SERVE_STATIC_FILES']

💡 Hint

Check how to properly assign a boolean based on environment variable presence.

The correct syntax uses ENV['RAILS_SERVE_STATIC_FILES'].present? to check if the environment variable is set and assigns a boolean accordingly.

❓ state_output

advanced

What is the value of config.log_level after this production config runs?

Given this snippet in config/environments/production.rb:

Rails.application.configure do
  config.log_level = :info
  config.log_level = :debug if ENV['DEBUG_LOG'] == 'true'
end

If the environment variable DEBUG_LOG is not set, what is the final value of config.log_level?

A :debug

B :info

C nil

D Raises an error because ENV['DEBUG_LOG'] is nil

💡 Hint

Consider what happens when the environment variable is missing.

If ENV['DEBUG_LOG'] is not set, the condition ENV['DEBUG_LOG'] == 'true' is false, so config.log_level remains :info.

🔧 Debug

advanced

Why does this production config cause an error?

Examine this production environment configuration snippet:

Rails.application.configure do
  config.action_mailer.raise_delivery_errors = true
  config.action_mailer.delivery_method = :smtp
  config.action_mailer.smtp_settings = {
    address: 'smtp.example.com',
    port: 587,
    domain: 'example.com',
    user_name: ENV['SMTP_USER'],
    password: ENV['SMTP_PASS'],
    authentication: 'plain',
    enable_starttls_auto: true
  }
end

Why does this code raise a syntax error?

A Missing commas between some hash key-value pairs cause a syntax error.

B Using symbols as keys in smtp_settings is not allowed in production config.

C The delivery_method :smtp is invalid in production environment.

D ENV variables cannot be used directly in production config files.

💡 Hint

Look carefully at punctuation between hash entries.

In Ruby hashes, commas are required between key-value pairs. Missing commas after address: 'smtp.example.com' and domain: 'example.com' cause syntax errors.

🧠 Conceptual

expert

Which production config setting ensures assets are precompiled and digest filenames are used?

In Rails production configuration, which setting ensures that assets are precompiled and served with digest fingerprints for caching?

A config.assets.precompile = false

B config.assets.compile = true

C config.assets.debug = true

D config.assets.digest = true

💡 Hint

Think about how Rails manages asset filenames for caching in production.

config.assets.digest = true enables fingerprinting of asset filenames, which helps browsers cache assets effectively. This is standard in production.