net/network_manager: do not set "may-fail" to False for both ipv6 and…

… ipv6

If "may-fail" set set to False in the Network Manager keyfile for both ipv4
and ipv6, it essentially means both ipv4 and ipv6 network initialization must
succeed for the overall network configuration to succeed. This means, for
environments where only ipv4 or ipv6 is available but not both, the overall
network configuration will fail. This is not what we want. When both ipv4 and
ipv6 are configured, it is enough for the overall configuration to succeed if
any one succeeds. Therefore, set "may-fail" to True when both ipv4 and ipv6
are configured in the Network Manager keyfile for both ipv4 and ipv6.

Please see discussions in PR canonical#4474.

Signed-off-by: Ani Sinha <anisinha@redhat.com>

cloudinit/net/network_manager.py

@@ -71,6 +71,46 @@ def _set_default(self, section, option, value):
         if not self.config.has_option(section, option):
             self.config[section][option] = value
 
+    def _config_option_is_set(self, section, option):
+        """
+        Checks if a config option is set.
+        """
+        return self.config.has_section(section) and self.config.has_option(
+            section, option
+        )
+
+    def _get_config_option(self, section, option):
+        """
+        Returns a config option if its set, else returns
+        None.
+        """
+        if self._config_option_is_set(section, option):
+            return self.config[section][option]
+        else:
+            return None
+
+    def _change_set_config_option(self, section, option, value):
+        """
+        Overrides the value of a config option if its already set.
+        Else, if the config option is not set, it does nothing.
+        """
+        if self._config_option_is_set(section, option):
+            self.config[section][option] = value
+
+    def _set_mayfail_true_if_both_false(self):
+        """
+        If for both ipv4 and ipv6, 'may-fail' is set to be False,
+        set it to True for both of them.
+        """
+        for family in ["ipv4", "ipv6"]:
+            if not self._config_option_is_set(family, "may-fail"):
+                return
+            if self._get_config_option(family, "may-fail") == "true":
+                return
+
+        for family in ["ipv4", "ipv6"]:
+            self._change_set_config_option(family, "may-fail", "true")
+
     def _set_ip_method(self, family, subnet_type):
         """
         Ensures there's appropriate [ipv4]/[ipv6] for given family
@@ -115,6 +155,13 @@ def _set_ip_method(self, family, subnet_type):
 
         self.config[family]["method"] = method
         self._set_default(family, "may-fail", "false")
+        # we do not want to set may-fail to false for both ipv4 and ipv6 at the
+        # at the same time. This will make the network configuration work only
+        # when both ipv4 and ipv6 succeeds which may not be true for most
+        # environments. We want any one to succeed in those cases. So in the
+        # case where "may-fail" is set to False for both ipv4 and ipv6, set
+        # them both to True.
+        self._set_mayfail_true_if_both_false()
 
     def _add_numbered(self, section, key_prefix, value):
         """

tests/unittests/test_net.py

@@ -1425,11 +1425,11 @@
 
                 [ipv4]
                 method=auto
-                may-fail=false
+                may-fail=true
 
                 [ipv6]
                 method=auto
-                may-fail=false
+                may-fail=true
 
                 """
             ),
@@ -1558,12 +1558,12 @@
 
                 [ipv4]
                 method=manual
-                may-fail=false
+                may-fail=true
                 address1=192.168.14.2/24
 
                 [ipv6]
                 method=manual
-                may-fail=false
+                may-fail=true
                 address1=2001:1::1/64
 
                 """
@@ -1598,11 +1598,11 @@
 
                 [ipv6]
                 method=auto
-                may-fail=false
+                may-fail=true
 
                 [ipv4]
                 method=auto
-                may-fail=false
+                may-fail=true
 
                 """
             ),
@@ -2876,12 +2876,12 @@
 
                 [ipv4]
                 method=manual
-                may-fail=false
+                may-fail=true
                 address1=192.168.14.2/24
 
                 [ipv6]
                 method=manual
-                may-fail=false
+                may-fail=true
                 address1=2001:1::1/64
                 route1=::/0,2001:4800:78ff:1b::1
 
@@ -3537,15 +3537,15 @@
 
                 [ipv4]
                 method=manual
-                may-fail=false
+                may-fail=true
                 address1=192.168.0.2/24
                 gateway=192.168.0.1
                 route1=10.1.3.0/24,192.168.0.3
                 address2=192.168.1.2/24
 
                 [ipv6]
                 method=manual
-                may-fail=false
+                may-fail=true
                 address1=2001:1::1/92
                 route1=2001:67c::/32,2001:67c:1562::1
                 route2=3001:67c::/32,3001:67c:15::1
@@ -3659,14 +3659,14 @@
 
                 [ipv4]
                 method=manual
-                may-fail=false
+                may-fail=true
                 address1=192.168.2.2/24
                 address2=192.168.1.2/24
                 gateway=192.168.1.1
 
                 [ipv6]
                 method=manual
-                may-fail=false
+                may-fail=true
                 address1=2001:1::bbbb/96
                 route1=::/0,2001:1::1
 
@@ -5984,11 +5984,11 @@ def test_default_generation(
 
                 [ipv4]
                 method=auto
-                may-fail=false
+                may-fail=true
 
                 [ipv6]
                 method=auto
-                may-fail=false
+                may-fail=true
 
                 """
                 ),