diff -r ea8e27e6098d -r d73f23344dc7 mercurial/hgweb/__init__.py
--- a/mercurial/hgweb/__init__.py	Sat Oct 31 21:57:45 2015 +0900
+++ b/mercurial/hgweb/__init__.py	Sat Oct 31 22:15:16 2015 +0900
@@ -13,6 +13,7 @@
 from ..i18n import _
 
 from .. import (
+    error,
     util,
 )
 
@@ -83,3 +84,32 @@
 
     def run(self):
         self.httpd.serve_forever()
+
+def createservice(ui, repo, opts):
+    # this way we can check if something was given in the command-line
+    if opts.get('port'):
+        opts['port'] = util.getport(opts.get('port'))
+
+    if repo:
+        baseui = repo.baseui
+    else:
+        baseui = ui
+    optlist = ("name templates style address port prefix ipv6"
+               " accesslog errorlog certificate encoding")
+    for o in optlist.split():
+        val = opts.get(o, '')
+        if val in (None, ''): # should check against default options instead
+            continue
+        baseui.setconfig("web", o, val, 'serve')
+        if repo and repo.ui != baseui:
+            repo.ui.setconfig("web", o, val, 'serve')
+
+    o = opts.get('web_conf') or opts.get('webdir_conf')
+    if not o:
+        if not repo:
+            raise error.RepoError(_("there is no Mercurial repository"
+                                    " here (.hg not found)"))
+        o = repo
+
+    app = hgweb(o, baseui=baseui)
+    return httpservice(ui, app, opts)