addons: dhcp: add vrf awareness

Ticket: CM-10292, CM-10282
Reviewed By: dsa, nikhil, julien
Testing Done: Tested dhcp config on an vrf slave

- Add support for policy module_globals variable
  "vrf-exec-cmd-prefix". It is read into per module
  self.vrf_exec_cmd_prefix variable

- If self.vrf_exec_cmd_prefix is present and interface is a
  vrf slave, use ifupdown2 will call such command in vrf
  context using:
    "%s %s %s" %(<vrf-exec-cmd-prefix>, <vrfname>, <cmd>)

- This also fixes calling of dhcp refresh when a dhcp slave is
  removed from a vrf

Signed-off-by: Roopa Prabhu <roopa@cumulusnetworks.com>

ifupdownaddons/dhclient.py

@@ -29,7 +29,18 @@ class dhclient(utilsBase):
     def is_running6(self, ifacename):
         return self._pid_exists('/run/dhclient6.%s.pid' %ifacename)
 
-    def stop(self, ifacename):
+    def _run_dhclient_cmd(self, cmd, cmd_prefix=None):
+        if not cmd_prefix:
+            cmd_aslist = []
+        else:
+            cmd_aslist = cmd_prefix.split()
+        if cmd_aslist:
+            cmd_aslist.extend(cmd)
+        else:
+            cmd_aslist = cmd
+        self.subprocess_check_call(cmd_aslist)
+
+    def stop(self, ifacename, cmd_prefix=None):
         if os.path.exists('/sbin/dhclient3'):
             cmd = ['/sbin/dhclient3', '-x', '-pf',
                    '/run/dhclient.%s.pid' %ifacename, '-lf',
@@ -40,23 +51,24 @@ class dhclient(utilsBase):
                    '/run/dhclient.%s.pid' %ifacename,
                    '-lf', '/var/lib/dhcp/dhclient.%s.leases' %ifacename,
                    '%s' %ifacename]
-        self.subprocess_check_call(cmd)
+        self._run_dhclient_cmd(cmd, cmd_prefix)
 
-    def start(self, ifacename, wait=True):
+    def start(self, ifacename, wait=True, cmd_prefix=None):
         if os.path.exists('/sbin/dhclient3'):
             cmd = ['/sbin/dhclient3', '-pf',
                    '/run/dhclient.%s.pid' %ifacename,
                    '-lf', '/var/lib/dhcp3/dhclient.%s.leases' %ifacename,
                    '%s' %ifacename]
         else:
-            cmd = ['/sbin/dhclient', '-pf', '/run/dhclient.%s.pid' %ifacename,
-                   '-lf', '/var/lib/dhcp/dhclient.%s.leases' %ifacename,
+            cmd = ['/sbin/dhclient', '-pf',
+                   '/run/dhclient.%s.pid' %ifacename, '-lf',
+                   '/var/lib/dhcp/dhclient.%s.leases' %ifacename,
                    '%s' %ifacename]
         if not wait:
             cmd.append('-nw')
-        self.subprocess_check_call(cmd)
+        self._run_dhclient_cmd(cmd, cmd_prefix)
 
-    def release(self, ifacename):
+    def release(self, ifacename, cmd_prefix=None):
         if os.path.exists('/sbin/dhclient3'):
             cmd = ['/sbin/dhclient3', '-r', '-pf',
                    '/run/dhclient.%s.pid' %ifacename, '-lf',
@@ -67,25 +79,27 @@ class dhclient(utilsBase):
                    '/run/dhclient.%s.pid' %ifacename,
                    '-lf', '/var/lib/dhcp/dhclient.%s.leases' %ifacename,
                    '%s' %ifacename]
-        self.subprocess_check_call(cmd)
+        self._run_dhclient_cmd(cmd, cmd_prefix)
 
-    def start6(self, ifacename, wait=True):
-        cmd = ['dhclient', '-6', '-pf',
+    def start6(self, ifacename, wait=True, cmd_prefix=None):
+        cmd = ['/sbin/dhclient', '-6', '-pf',
                 '/run/dhclient6.%s.pid' %ifacename, '-lf',
                 '/var/lib/dhcp/dhclient.%s.leases ' %ifacename,
                 '%s' %ifacename]
         if not wait:
             cmd.append('-nw')
-        self.subprocess_check_call(cmd)
+        self._run_dhclient_cmd(cmd, cmd_prefix)
 
-    def stop6(self, ifacename):
-        self.subprocess_check_call(['dhclient', '-6', '-x', '-pf',
-                '/run/dhclient.%s.pid' %ifacename, '-lf',
-                '/var/lib/dhcp/dhclient.%s.leases ' %ifacename,
-                '%s' %ifacename])
+    def stop6(self, ifacename, cmd_prefix=None):
+        cmd = ['/sbin/dhclient', '-6', '-x', '-pf',
+               '/run/dhclient.%s.pid' %ifacename, '-lf',
+               '/var/lib/dhcp/dhclient.%s.leases ' %ifacename,
+               '%s' %ifacename]
+        self._run_dhclient_cmd(cmd, cmd_prefix)
 
-    def release6(self, ifacename):
-        self.subprocess_check_call(['dhclient', '-6', '-r', '-pf',
-                '/run/dhclient6.%s.pid' %ifacename, '-lf',
-                '/var/lib/dhcp/dhclient6.%s.leases' %ifacename,
-                '%s' %ifacename])
+    def release6(self, ifacename, cmd_prefix=None):
+        cmd = ['/sbin/dhclient', '-6', '-r', '-pf',
+               '/run/dhclient6.%s.pid' %ifacename, '-lf',
+               '/var/lib/dhcp/dhclient6.%s.leases' %ifacename,
+               '%s' %ifacename]
+        self._run_dhclient_cmd(cmd, cmd_prefix)

ifupdownaddons/modulebase.py

@@ -15,6 +15,7 @@ import shlex
 
 from ifupdown.utils import utils
 from ifupdown.iface import *
+import ifupdown.policymanager as policymanager
 #from ifupdownaddons.iproute2 import *
 #from ifupdownaddons.dhclient import *
 #from ifupdownaddons.bridgeutils import *
@@ -38,6 +39,11 @@ class moduleBase(object):
         self.CACHE = kargs.get('cache', False)
         self.CACHE_FLAGS = kargs.get('cacheflags', 0x0)
 
+        # vrfs are a global concept and a vrf context can be applicable
+        # to all global vrf commands. Get the default vrf-exec-cmd-prefix
+        # here so that all modules can use it
+        self.vrf_exec_cmd_prefix = policymanager.policymanager_api.get_module_globals('vrf', attr='vrf-exec-cmd-prefix')
+
     def log_warn(self, str, ifaceobj=None):
         """ log a warning if err str is not one of which we should ignore """
         if not self.ignore_error(str):