Rails - Asset is not present in asset pipeline when using image_tag

Question

Goal: Using my rails app with static images in assets in production environemt

Steps:

1. I turned my rails app to production environment.
2. Precompiled the assets with RAILS_ENV=production rails assets:precompile
3. Set RAILS_SERVE_STATIC_FILES environemt variable to true to enable public file server (in production.rb - config.public_file_server.enabled = ENV['RAILS_SERVE_STATIC_FILES'].present?
4. Added line config.serve_static_assets = true to /config/application.rb

With this setup, I`ve started the server.

I have a few static images in /app/assets/images/ which precompiled versions with fingerprint filename are now in /public/assets. Examples:

• aussen-d2fb0029a12281121a1752c599e715a8e2b3db17f1e8e18248a79a7b1ca63b91.jpg
• hintergrund-ca80e1ae5a697c86898f3a7e107694a76dc12e54320b8ac80c58eecbffe0414a.png

So far so great.

When I use background-image: url(<%= asset_path('hintergrund') %>); in application.css.erb it successfully loads the precompiled background-image from /public/assets.

Problem: I can't access the precompiled images with my image_tags in the views! Example:

<%= image_tag("aussen") %>

Error Logs:

I, [2018-03-23T00:46:29.133381 #9289]  INFO -- : [f36ff000-6261-4c2c-bfcc-4a2f80cae682] Started GET "/" for 46.142.136.81 at 2018-03-23 00:46:29 +0100
I, [2018-03-23T00:46:29.134466 #9289]  INFO -- : [f36ff000-6261-4c2c-bfcc-4a2f80cae682] Processing by HomeController#index as HTML
I, [2018-03-23T00:46:29.136604 #9289]  INFO -- : [f36ff000-6261-4c2c-bfcc-4a2f80cae682]   Rendering home/index.html.erb within layouts/application
I, [2018-03-23T00:46:29.138267 #9289]  INFO -- : [f36ff000-6261-4c2c-bfcc-4a2f80cae682]   Rendered home/index.html.erb within layouts/application (1.5ms)
I, [2018-03-23T00:46:29.138482 #9289]  INFO -- : [f36ff000-6261-4c2c-bfcc-4a2f80cae682] Completed 500 Internal Server Error in 4ms
F, [2018-03-23T00:46:29.139546 #9289] FATAL -- : [f36ff000-6261-4c2c-bfcc-4a2f80cae682]
F, [2018-03-23T00:46:29.139635 #9289] FATAL -- : [f36ff000-6261-4c2c-bfcc-4a2f80cae682] ActionView::Template::Error (The asset "aussen" is not present in the asset pipeline.):
F, [2018-03-23T00:46:29.139798 #9289] FATAL -- : [f36ff000-6261-4c2c-bfcc-4a2f80cae682]     1: <%= image_tag("aussen", id: "home-img", alt: "Aussenansicht von Simson-Seelig") %>
[f36ff000-6261-4c2c-bfcc-4a2f80cae682]     2: <div id="home" class="content">
[f36ff000-6261-4c2c-bfcc-4a2f80cae682]     3:   <p>Alles für Simson von Simson-Seelig.</p>
[f36ff000-6261-4c2c-bfcc-4a2f80cae682]     4:   <p>Für die legendären Schwalben und alle anderen SIMSON-Modelle bieten wir Ersatzteile und Service. </p>
F, [2018-03-23T00:46:29.139867 #9289] FATAL -- : [f36ff000-6261-4c2c-bfcc-4a2f80cae682]
F, [2018-03-23T00:46:29.139930 #9289] FATAL -- : [f36ff000-6261-4c2c-bfcc-4a2f80cae682] app/views/home/index.html.erb:1:in `_app_views_home_index_html_erb__177499641769

After hours of researching, I still don't get why I can access the precompiled image in the stylesheet, but not in the view with the image_tag.

Additional information:

$ ruby --version
ruby 2.4.3p205 (2017-12-14 revision 61247) [x86_64-linux]

$ rails --version
Rails 5.1.4

/config/application.rb:

require_relative 'boot'

require 'rails/all'

# Require the gems listed in Gemfile, including any gems
# you've limited to :test, :development, or :production.
Bundler.require(*Rails.groups)

module SimsonSeelig
  class Application < Rails::Application
    # Initialize configuration defaults for originally generated Rails version.
    config.load_defaults 5.1

    # Settings in config/environments/* take precedence over those specified here.
    # Application configuration should go into files in config/initializers
    # -- all .rb files in that directory are automatically loaded.

    # Enable rails to serve my assets
    config.serve_static_assets = true
  end
end

production.rb:

Rails.application.configure do
  # Settings specified here will take precedence over those in config/application.rb.

  # Code is not reloaded between requests.
  config.cache_classes = true

  # Eager load code on boot. This eager loads most of Rails and
  # your application in memory, allowing both threaded web servers
  # and those relying on copy on write to perform better.
  # Rake tasks automatically ignore this option for performance.
  config.eager_load = true

  # Full error reports are disabled and caching is turned on.
  config.consider_all_requests_local       = false
  config.action_controller.perform_caching = true

  # Attempt to read encrypted secrets from `config/secrets.yml.enc`.
  # Requires an encryption key in `ENV["RAILS_MASTER_KEY"]` or
  # `config/secrets.yml.key`.
  config.read_encrypted_secrets = true

  # Disable serving static files from the `/public` folder by default since
  # Apache or NGINX already handles this.
  config.public_file_server.enabled = ENV['RAILS_SERVE_STATIC_FILES'].present?

  if ENV["RAILS_LOG_TO_STDOUT"].present?
    logger           = ActiveSupport::Logger.new(STDOUT)
    logger.formatter = config.log_formatter
    config.logger = ActiveSupport::TaggedLogging.new(logger)
  end

  # Compress JavaScripts and CSS.
  config.assets.js_compressor = :uglifier
  # config.assets.css_compressor = :sass

  # Do not fallback to assets pipeline if a precompiled asset is missed.
  config.assets.compile = false

  # `config.assets.precompile` and `config.assets.version` have moved to config/initializers/assets.rb

  # Enable serving of images, stylesheets, and JavaScripts from an asset server.
  # config.action_controller.asset_host = 'http://assets.example.com'

  # Specifies the header that your server uses for sending files.
  # config.action_dispatch.x_sendfile_header = 'X-Sendfile' # for Apache
  # config.action_dispatch.x_sendfile_header = 'X-Accel-Redirect' # for NGINX

  # Mount Action Cable outside main process or domain
  # config.action_cable.mount_path = nil
  # config.action_cable.url = 'wss://example.com/cable'
  # config.action_cable.allowed_request_origins = [ 'http://example.com', /http:\/\/example.*/ ]

  # Force all access to the app over SSL, use Strict-Transport-Security, and use secure cookies.
  # config.force_ssl = true

  # Use the lowest log level to ensure availability of diagnostic information
  # when problems arise.
  config.log_level = :debug

  # Prepend all log lines with the following tags.
  config.log_tags = [ :request_id ]

  # Use a different cache store in production.
  # config.cache_store = :mem_cache_store

  # Use a real queuing backend for Active Job (and separate queues per environment)
  # config.active_job.queue_adapter     = :resque
  # config.active_job.queue_name_prefix = "simson-seelig_#{Rails.env}"
  config.action_mailer.perform_caching = false

  # Ignore bad email addresses and do not raise email delivery errors.
  # Set this to true and configure the email server for immediate delivery to raise delivery errors.
  # config.action_mailer.raise_delivery_errors = false

  # Enable locale fallbacks for I18n (makes lookups for any locale fall back to
  # the I18n.default_locale when a translation cannot be found).
  config.i18n.fallbacks = true

  # Send deprecation notices to registered listeners.
  config.active_support.deprecation = :notify

  # Use default logging formatter so that PID and timestamp are not suppressed.
  config.log_formatter = ::Logger::Formatter.new

  # Use a different logger for distributed setups.
  # require 'syslog/logger'
  # config.logger = ActiveSupport::TaggedLogging.new(Syslog::Logger.new 'app-name')

  if ENV["RAILS_LOG_TO_STDOUT"].present?
    logger           = ActiveSupport::Logger.new(STDOUT)
    logger.formatter = config.log_formatter
    config.logger    = ActiveSupport::TaggedLogging.new(logger)
  end

  # Do not dump schema after migrations.
  config.active_record.dump_schema_after_migration = false
end

/config/initializers/assets.rb:

# Be sure to restart your server when you modify this file.

# Version of your assets, change this if you want to expire all your assets.
Rails.application.config.assets.version = '1.0'

# Add additional assets to the asset load path.
# Rails.application.config.assets.paths << Emoji.images_path
# Add Yarn node_modules folder to the asset load path.
Rails.application.config.assets.paths << Rails.root.join('node_modules')

# Precompile additional assets.
# application.js, application.css, and all non-JS/CSS in the app/assets
# folder are already added.
# Rails.application.config.assets.precompile += %w( admin.js admin.css )

Answer 1

The asset "aussen" is not present in the asset pipeline.

Technically true because you have not aussen but you have aussen.jpg so it will be <%= image_tag("aussen.jpg") %>

Look, while you use <%= image_tag("aussen") %> then it will be genarate HTML like this

<%= image_tag("aussen") %>
#=> <img alt="Aussen" src="/assets/aussen" />

While you use <%= image_tag("aussen.jpg") %> then it will be genarate HTML like this

<%= image_tag("aussen.jpg") %>
#=> <img alt="Aussen" src="/assets/aussen.jpg" />

When it's going into production mode then it will be shown some encrypted key on the page source like this

aussen-d2fb0029a12281121a1752c599e715a8e2b3db17f1e8e18248a79a7b1ca63b91.jpg

image_tag AssetTagHelper see this for reference.

Update production.rb file config.assets.compile false to true

# config/environments/production.rb
...
config.assets.compile = true
...