Add master_url

Author: Brad Miller

runestone/__init__.py

@@ -21,7 +21,7 @@
 from .webgldemo import *
 
 
-import os, sys
+import os, sys, socket
 
 def runestone_static_dirs():
     basedir = os.path.dirname(__file__)
@@ -47,6 +47,18 @@ def runestone_extensions():
     modules.insert(0, modules.pop(modules.index('runestone.common')))
     return modules
 
+def master_url():
+    if socket.gethostname() in ['runestone-deploy', 'rsbuilder']:
+        master_url = 'https://runestone.academy'
+    elif 'RUNESTONE_HOST' in os.environ:
+        port = os.environ.get('RUNESTONE_PORT', 80)
+        secure = os.environ.get('RUNESTONE_PROTOCOL','http')
+        master_url = '{}://{}:{}'.format(secure, os.environ['RUNESTONE_HOST'], port)
+    else:
+        master_url = 'http://127.0.0.1:8000'
+
+    return master_url
+
 from paver.easy import task, cmdopts, sh
 from sphinxcontrib import paverutils