FIX: show letter avatars even if NGINX is not running in Dev mode

app/controllers/user_avatars_controller.rb

@@ -3,7 +3,7 @@ require_dependency 'letter_avatar'
 class UserAvatarsController < ApplicationController
   DOT = Base64.decode64("R0lGODlhAQABALMAAAAAAIAAAACAAICAAAAAgIAAgACAgMDAwICAgP8AAAD/AP//AAAA//8A/wD//wBiZCH5BAEAAA8ALAAAAAABAAEAAAQC8EUAOw==")
 
-  skip_before_filter :preload_json, :redirect_to_login_if_required, :check_xhr, :verify_authenticity_token, only: [:show, :show_letter]
+  skip_before_filter :preload_json, :redirect_to_login_if_required, :check_xhr, :verify_authenticity_token, only: [:show, :show_letter, :show_proxy_letter]
 
   def refresh_gravatar
     user = User.find_by(username_lower: params[:username].downcase)
@@ -22,6 +22,26 @@ class UserAvatarsController < ApplicationController
     end
   end
 
+  # mainly used in development for backwards compat
+  def show_proxy_letter
+    params.require(:letter)
+    params.require(:color)
+    params.require(:version)
+    params.require(:size)
+
+    no_cookies
+
+    identity = LetterAvatar::Identity.new
+    identity.letter = params[:letter].to_s[0].upcase
+    identity.color = params[:color].scan(/../).map(&:hex)
+    image = LetterAvatar.generate(params[:letter].to_s, params[:size].to_i, identity: identity)
+
+    response.headers["Last-Modified"] = File.ctime(image).httpdate
+    response.headers["Content-Length"] = File.size(image).to_s
+    expires_in 1.year, public: true
+    send_file image, disposition: nil
+  end
+
   def show_letter
     params.require(:username)
     params.require(:version)

config/routes.rb

@@ -314,6 +314,9 @@ Discourse::Application.routes.draw do
   get "letter_avatar/:username/:size/:version.png" => "user_avatars#show_letter", format: false, constraints: { hostname: /[\w\.-]+/, size: /\d+/, username: USERNAME_ROUTE_FORMAT}
   get "user_avatar/:hostname/:username/:size/:version.png" => "user_avatars#show", format: false, constraints: { hostname: /[\w\.-]+/, size: /\d+/, username: USERNAME_ROUTE_FORMAT }
 
+  # in most production settings this is bypassed
+  get "letter_avatar_proxy/:version/letter/:letter/:color/:size.png" => "user_avatars#show_proxy_letter"
+
   get "highlight-js/:hostname/:version.js" => "highlight_js#show", format: false, constraints: { hostname: /[\w\.-]+/ }
 
   get "stylesheets/:name.css" => "stylesheets#show", constraints: { name: /[a-z0-9_]+/ }

lib/letter_avatar.rb

@@ -1,5 +1,18 @@
 class LetterAvatar
 
+  class Identity
+    attr_accessor :color, :letter
+
+    def self.from_username(username)
+      identity = new
+      identity.color = LetterAvatar::COLORS[
+        Digest::MD5.hexdigest(username)[0...15].to_i(16) % LetterAvatar::COLORS.length
+      ]
+      identity.letter = username[0].upcase
+      identity
+    end
+  end
+
   # BUMP UP if avatar algorithm changes
   VERSION = 5
 
@@ -9,19 +22,6 @@ class LetterAvatar
 
   class << self
 
-    class Identity
-      attr_accessor :color, :letter
-
-      def self.from_username(username)
-        identity = new
-        identity.color = LetterAvatar::COLORS[
-          Digest::MD5.hexdigest(username)[0...15].to_i(16) % LetterAvatar::COLORS.length
-        ]
-        identity.letter = username[0].upcase
-        identity
-      end
-    end
-
     def version
       "#{VERSION}_#{image_magick_version}"
     end
@@ -32,7 +32,7 @@ class LetterAvatar
 
     def generate(username, size, opts = nil)
       DistributedMutex.synchronize("letter_avatar_#{version}_#{username}") do
-        identity = Identity.from_username(username)
+        identity = (opts && opts[:identity]) || LetterAvatar::Identity.from_username(username)
 
         cache = true
         cache = false if opts && opts[:cache] == false