Merge ~pjdc/ubuntu-mirror-charm/+git/ubuntu-mirror-charm:default-v6 into ubuntu-mirror-charm:master

[Paul Collins]

rewrite my_ipaddr as get_default_address

[🤖 Canonical IS Merge Bot (canonical-is-mergebot)]

This merge proposal is being monitored by mergebot. Change the status to Approved to merge.

[Haw Loeung (hloeung)]

LGTM

review: Approve (+1)

[🤖 Canonical IS Merge Bot (canonical-is-mergebot)]

Change successfully merged at revision 3775701f7862cf739540a60f76120a9f66ec9737

diff --git a/hooks/hooks.py b/hooks/hooks.py
index 448c752..f5b932e 100755
--- a/hooks/hooks.py
+++ b/hooks/hooks.py
@@ -80,20 +80,24 @@ def juju_header():
     return header
 
 
-#
-# Make an educated guess at our external IP address
-#
-def my_ipaddr():
-    s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
+# Google Public DNS addresses are good "cannot possibly be internal" destinations
+GET_DEFAULT_ADDRESS_DESTINATIONS = {
+    socket.AF_INET: ("8.8.8.8", 53),
+    socket.AF_INET6: ("2001:4860:4860::8888", 53),
+}
+
+
+def get_default_address(af):
+    """Determine our default address for the given address family."""
     try:
-        # Use some arbitrary external address here
-        s.connect(("ntp.ubuntu.com", 123))
-    except socket.error:
-        log("CHARM: Unable to determine local IP address - possible DNS issues")
-        return "127.0.1.1"
-    ipaddr = s.getsockname()[0]
-    s.close()
-    return ipaddr
+        s = socket.socket(af, socket.SOCK_DGRAM)
+        s.connect(GET_DEFAULT_ADDRESS_DESTINATIONS[af])
+        return s.getsockname()[0]
+    except Exception as e:
+        log("CHARM: Unable to determine local {} address: {}".format(af.name, str(e)))
+        return None
+    finally:
+        s.close()
 
 
 def get_pkg_version(name):
@@ -608,7 +612,12 @@ def configure_nrpe():
             if 'addresses' in role_config:
                 tmpl_data["ipaddr"] = ' '.join(role_config['addresses'])
             else:
-                tmpl_data["ipaddr"] = my_ipaddr()
+                ipaddr = get_default_address(socket.AF_INET)
+                if not ipaddr:
+                    error = 'Could not determine default IP address!'
+                    status_set('blocked', error)
+                    raise Exception(error)
+                tmpl_data["ipaddr"] = ipaddr
             tmpl_data["port"] = 80
             tmpl_data["role"] = role
             tmpl_data["path"] = mirror["path"]