serve and auto publishes DNS Service Discovery records

On Avahi/dbus systems (Linux/FreeBSD), running web servers are announced to the local network over DNS-SD so clients can more easily find these services. IPv6 annonce used with the `-6` switch. Will just give up if the required system python bindings are not present and will not make a fuzz about it.
getnikola · Oct 10, 2015 · 4572f4c · 4572f4c
1 parent 359a581
commit 4572f4c
Show file tree

Hide file tree

Showing 4 changed files with 36 additions and 2 deletions.
diff --git a/CHANGES.txt b/CHANGES.txt
@@ -3,6 +3,9 @@ New in master
 
 Features
 --------
+* ``serve`` and ``auto`` publishes DNS Service Discovery records
+  to the local network announcing they’re running web servers.
+
 
 Bugfixes
 --------

diff --git a/nikola/plugins/command/auto/__init__.py b/nikola/plugins/command/auto/__init__.py
@@ -63,7 +63,7 @@
 
 
 from nikola.plugin_categories import Command
-from nikola.utils import req_missing, get_logger, get_theme_path, STDERR_HANDLER
+from nikola.utils import dns_sd, req_missing, get_logger, get_theme_path, STDERR_HANDLER
 LRJS_PATH = os.path.join(os.path.dirname(__file__), 'livereload.js')
 error_signal = signal('error')
 refresh_signal = signal('refresh')
@@ -85,6 +85,8 @@ class CommandAuto(Command):
     logger = None
     has_server = True
     doc_purpose = "builds and serves a site; automatically detects site changes, rebuilds, and optionally refreshes a browser"
+    dns_sd = None
+
     cmd_options = [
         {
             'name': 'port',
@@ -233,9 +235,12 @@ def __call__(self, environ, start_response):
                 webbrowser.open('http://{0}:{1}'.format(host, port))
 
             try:
+                self.dns_sd = dns_sd(port, (options['ipv6'] or '::' in host))
                 ws.serve_forever()
             except KeyboardInterrupt:
                 self.logger.info("Server is shutting down.")
+                if self.dns_sd:
+                    self.dns_sd.Reset()
                 # This is a hack, but something is locking up in a futex
                 # and exit() doesn't work.
                 os.kill(os.getpid(), 15)

diff --git a/nikola/plugins/command/serve.py b/nikola/plugins/command/serve.py
@@ -45,7 +45,7 @@
 
 
 from nikola.plugin_categories import Command
-from nikola.utils import get_logger, STDERR_HANDLER
+from nikola.utils import dns_sd, get_logger, STDERR_HANDLER
 
 
 class IPv6Server(HTTPServer):
@@ -61,6 +61,7 @@ class CommandServe(Command):
     doc_usage = "[options]"
     doc_purpose = "start the test webserver"
     logger = None
+    dns_sd = None
 
     cmd_options = (
         {
@@ -150,9 +151,12 @@ def _execute(self, options, args):
                         raise e
             else:
                 try:
+                    self.dns_sd = dns_sd(options['port'], (options['ipv6'] or '::' in options['address']))
                     httpd.serve_forever()
                 except KeyboardInterrupt:
                     self.logger.info("Server is shutting down.")
+                    if self.dns_sd:
+                        self.dns_sd.Reset()
                     return 130
 
 

diff --git a/nikola/utils.py b/nikola/utils.py
@@ -1813,6 +1813,28 @@ def color_hsl_adjust_hex(hexstr, adjust_h=None, adjust_s=None, adjust_l=None):
     return husl.husl_to_hex(h, s, l)
 
 
+def dns_sd(port, inet6):
+    """Optimistically publish a HTTP service to the local network over DNS-SD. (Linux/FreeBSD only.)"""
+    try:
+        import avahi
+        import dbus
+        inet = avahi.PROTO_INET6 if inet6 else avahi.PROTO_INET
+        bus = dbus.SystemBus()
+        bus_server = dbus.Interface(bus.get_object(avahi.DBUS_NAME,
+                                                   avahi.DBUS_PATH_SERVER),
+                                    avahi.DBUS_INTERFACE_SERVER)
+        bus_group = dbus.Interface(bus.get_object(avahi.DBUS_NAME,
+                                                  bus_server.EntryGroupNew()),
+                                   avahi.DBUS_INTERFACE_ENTRY_GROUP)
+        bus_group.AddService(avahi.IF_UNSPEC, inet, dbus.UInt32(0),
+                             'Nikola Server', '_http._tcp', '', '',
+                             dbus.UInt16(port), '')
+        bus_group.Commit()
+        return bus_group  # remember to bus_group.Reset() to unpublish
+    except:
+        return None
+
+
 # Stolen from textwrap in Python 3.4.3.
 def indent(text, prefix, predicate=None):
     """Add 'prefix' to the beginning of selected lines in 'text'.