Adds a simple string templating system for fetch vars not yet set

config/deploy.rb

@@ -46,23 +46,25 @@
 
 # files which need to be symlinked to other parts of the
 # filesystem. For example nginx virtualhosts, log rotation
-# init scripts etc.
+# init scripts etc. The full_app_name variable isn't
+# available at this point so we use a custom template {{}}
+# tag and then add it at run time.
 set(:symlinks, [
   {
     source: "nginx.conf",
-    link: "/etc/nginx/sites-enabled/#{fetch(:full_app_name)}"
+    link: "/etc/nginx/sites-enabled/{{full_app_name}}"
   },
   {
     source: "unicorn_init.sh",
-    link: "/etc/init.d/unicorn_#{fetch(:full_app_name)}"
+    link: "/etc/init.d/unicorn_{{full_app_name}}"
   },
   {
     source: "log_rotation",
-   link: "/etc/logrotate.d/#{fetch(:full_app_name)}"
+   link: "/etc/logrotate.d/{{full_app_name}}"
   },
   {
     source: "monit",
-    link: "/etc/monit/conf.d/#{fetch(:full_app_name)}.conf"
+    link: "/etc/monit/conf.d/{{full_app_name}}.conf"
   }
 ])
 

lib/capistrano/substitute_strings.rb

@@ -0,0 +1,12 @@
+# we often want to refer to variables which
+# are defined in subsequent stage files. This
+# let's us use the {{var}} to represent fetch(:var)
+# in strings which are only evaluated at runtime.
+
+def sub_strings(input_string)
+  output_string = input_string
+  input_string.scan(/{{(\w*)}}/).each do |var|
+    output_string.gsub!("{{#{var[0]}}}", fetch(var[0].to_sym))
+  end
+  output_string
+end

lib/capistrano/tasks/setup_config.cap

@@ -26,7 +26,7 @@ namespace :deploy do
       symlinks = fetch(:symlinks)
 
       symlinks.each do |symlink|
-        sudo "ln -nfs #{shared_path}/config/#{symlink[:source]} #{symlink[:link]}"
+        sudo "ln -nfs #{shared_path}/config/#{symlink[:source]} #{sub_strings(symlink[:link])}"
       end
     end
   end