`shipit` shells out to a JavaScript runtime

[XrXr]

While trying to run the shipit benchmark:

[b4108cc5-f95b-473f-804e-40aae2c7b87a]   
[b4108cc5-f95b-473f-804e-40aae2c7b87a] ActionView::Template::Error (Could not find a JavaScript runtime. See https://github.com/rails/execjs for a list of available ru
ntimes.)
[b4108cc5-f95b-473f-804e-40aae2c7b87a] Caused by: ExecJS::RuntimeUnavailable (Could not find a JavaScript runtime. See https://github.com/rails/execjs for a list of av
ailable runtimes.)
[b4108cc5-f95b-473f-804e-40aae2c7b87a] 
Information for: ActionView::Template::Error (Could not find a JavaScript runtime. See https://github.com/rails/execjs for a list of available runtimes.):
[b4108cc5-f95b-473f-804e-40aae2c7b87a]      7:   <title><%= Shipit.app_name %></title>
[b4108cc5-f95b-473f-804e-40aae2c7b87a]      8:   <% end %>
[b4108cc5-f95b-473f-804e-40aae2c7b87a]      9:   <meta name="viewport" content="width=device-width, initial-scale=1">
[b4108cc5-f95b-473f-804e-40aae2c7b87a]     10:   <%= favicon_link_tag %>
[b4108cc5-f95b-473f-804e-40aae2c7b87a]     11:   <%= stylesheet_link_tag :shipit, media: 'all' %>
[b4108cc5-f95b-473f-804e-40aae2c7b87a]     12:   <%= javascript_include_tag :shipit %>
[b4108cc5-f95b-473f-804e-40aae2c7b87a]     13:   <%= yield :update_subscription %>
[b4108cc5-f95b-473f-804e-40aae2c7b87a]   
[b4108cc5-f95b-473f-804e-40aae2c7b87a] execjs (2.10.0) lib/execjs/runtimes.rb:68:in 'ExecJS::Runtimes.autodetect'
[b4108cc5-f95b-473f-804e-40aae2c7b87a] execjs (2.10.0) lib/execjs.rb:6:in 'ExecJS.runtime'
[b4108cc5-f95b-473f-804e-40aae2c7b87a] execjs (2.10.0) lib/execjs/module.rb:27:in 'ExecJS.compile'
[b4108cc5-f95b-473f-804e-40aae2c7b87a] coffee-script (2.4.1) lib/coffee_script.rb:50:in 'CoffeeScript::Source.context'
[b4108cc5-f95b-473f-804e-40aae2c7b87a] coffee-script (2.4.1) lib/coffee_script.rb:78:in 'CoffeeScript.compile'
[b4108cc5-f95b-473f-804e-40aae2c7b87a] sprockets (3.7.5) lib/sprockets/coffee_script_processor.rb:21:in 'block in Sprockets::CoffeeScriptProcessor.call'
[b4108cc5-f95b-473f-804e-40aae2c7b87a] sprockets (3.7.5) lib/sprockets/cache.rb:85:in 'Sprockets::Cache#fetch'
[b4108cc5-f95b-473f-804e-40aae2c7b87a] sprockets (3.7.5) lib/sprockets/coffee_script_processor.rb:20:in 'Sprockets::CoffeeScriptProcessor.call'
[b4108cc5-f95b-473f-804e-40aae2c7b87a] sprockets (3.7.5) lib/sprockets/processor_utils.rb:75:in 'Sprockets::ProcessorUtils#call_processor'
[b4108cc5-f95b-473f-804e-40aae2c7b87a] sprockets (3.7.5) lib/sprockets/processor_utils.rb:57:in 'block in Sprockets::ProcessorUtils#call_processors'
[b4108cc5-f95b-473f-804e-40aae2c7b87a] sprockets (3.7.5) lib/sprockets/processor_utils.rb:56:in 'Array#reverse_each'
[b4108cc5-f95b-473f-804e-40aae2c7b87a] sprockets (3.7.5) lib/sprockets/processor_utils.rb:56:in 'Sprockets::ProcessorUtils#call_processors'
[b4108cc5-f95b-473f-804e-40aae2c7b87a] sprockets (3.7.5) lib/sprockets/loader.rb:134:in 'Sprockets::Loader#load_from_unloaded'
[b4108cc5-f95b-473f-804e-40aae2c7b87a] sprockets (3.7.5) lib/sprockets/loader.rb:60:in 'block in Sprockets::Loader#load'

We probably shouldn't be benchmarking the performance of a JS runtime while trying to benchmark ruby.

[k0kubun]

Copying discussions from Slack: Let's run assets:precompile before any warmup/benchmark iterations, and/or get rid of coffee-rails as @byroot suggested at Shopify/shipit-engine#1467.

[k0kubun]

🤔 Shopify/shipit-engine#1475

[k0kubun]

#494

[XrXr]

We should also set

# Don't fallback to assets pipeline if a precompiled asset is missed
config.assets.compile = false

in environment/production.rb.

[byroot]

I'm not sure getting rid of coffee-rails is worth it, also I suspect other parts of sprockets may need JS anyway.

I think we can either:

• config.assets.compile = false and just ignore all this.
• Run assets:precompile and commit the manifest.

The later might be better as it means we're exercise the asset lookup codepath like real production apps do.

[byroot]

The fix is here: #495