Added note as to why mapbox config isn't in application.yml

config/application.yml.example

@@ -2,6 +2,14 @@
 # copy and use to store your API credentials for external APIs used by
 # the Growstuff application.
 
+# We are progressively moving config variables out of
+# config/environments/*.rb and into this application.yml config instead.
+# Please do not add new config variables to config/environments.
+# There are however a couple of exceptions to this, particularly config
+# variables used by the assets pipeline, which cannot access ENV.  These
+# include:
+#   mapbox_map_id
+
 # To use it, copy application.yml.example to application.yml (which is
 # .gitignored) and fill in the appropriate values.
 

config/environments/development.rb

@@ -54,6 +54,8 @@ Growstuff::Application.configure do
   config.host = 'localhost:8080'
   config.analytics_code = ''
 
+  # this config variable cannot be put in application.yml as it is needed
+  # by the assets pipeline, which doesn't have access to ENV.
   config.mapbox_map_id = 'growstuff.i3n2il6a'
 
   config.after_initialize do

config/environments/production.rb

@@ -86,6 +86,8 @@ Growstuff::Application.configure do
     <noscript><p><img alt="Clicky" width="1" height="1" src="//in.getclicky.com/100594260ns.gif" /></p></noscript>
   eos
 
+  # this config variable cannot be put in application.yml as it is needed
+  # by the assets pipeline, which doesn't have access to ENV.
   config.mapbox_map_id = 'growstuff.i3n2c4ie'
 
   config.after_initialize do

config/environments/staging.rb

@@ -82,6 +82,8 @@ Growstuff::Application.configure do
   config.host = 'dev.growstuff.org'
   config.analytics_code = ''
 
+  # this config variable cannot be put in application.yml as it is needed
+  # by the assets pipeline, which doesn't have access to ENV.
   config.mapbox_map_id = 'growstuff.i3n2hao7'
 
   config.after_initialize do