Make calling service and chkconfig tolerant of the service not installed

For example, if nscd is not installed this would throw lots of errors about
not being able to disable it, stop it, etc.

ipa-client/ipa-install/ipa-client-install

@@ -32,7 +32,7 @@ try:
     import ipaclient.ipadiscovery
     import ipaclient.ipachangeconf
     import ipaclient.ntpconf
-    from ipapython.ipautil import run, user_input
+    from ipapython.ipautil import run, user_input, CalledProcessError
     from ipapython import sysrestore
     from ipapython import version
     import SSSDConfig
@@ -120,6 +120,56 @@ def nickname_exists(nickname):
         else:
             return False
 
+def service(name, status):
+    """
+    Run a System V init script 'name' with the status 'status'
+
+    The return value of /sbin/service name start/stop/status is:
+
+    0 - Ok
+    1 - unrecognized service, bad usage
+    > 1 - generally command-specific
+
+    For status == 'status' it means:
+    0 - running
+    1 - dead but pid file exists
+    2 - dead but sybsys locked
+    3 - stopped
+    """
+    (sout, serr, returncode) = run(['/sbin/service', name, 'status'], raiseonerr=False)
+
+    # If the service isn't installed return with no error
+    if returncode == 1:
+        return
+
+    args = ['/sbin/service', name, status]
+    (sout, serr, returncode) = run(args, raiseonerr=False)
+
+    if returncode != 0:
+        raise CalledProcessError(returncode, ' '.join(args))
+
+    return
+
+def chkconfig(name, status):
+    """
+    Set startup of service 'name' to 'status' (on or off)
+
+    chkconfig returns 1 if the service is unknown, 0 otherwise
+    """
+    (sout, serr, returncode) = run(['/sbin/chkconfig', name, '--list'], raiseonerr=False)
+
+    # If the service isn't installed return with no error
+    if returncode == 1:
+        return
+
+    args = ['/sbin/chkconfig', name, status]
+    (sout, serr, returncode) = run(args, raiseonerr=False)
+
+    if returncode != 0:
+        raise CalledProcessError(returncode, ' '.join(args))
+
+    return
+
 def uninstall(options):
 
     # Remove our host cert and CA cert
@@ -139,12 +189,12 @@ def uninstall(options):
             print "Failed to stop tracking Server-Cert in certmonger: %s" % str(e)
 
     try:
-        run(["/sbin/service", "certmonger", "stop"])
+        service('certmonger', 'stop')
     except:
         print "Failed to stop the certmonger daemon"
 
     try:
-        run(["/sbin/chkconfig", "certmonger", "off"])
+        chkconfig('certmonger', 'off')
     except:
         print "Failed to disable automatic startup of the certmonger daemon"
 
@@ -166,12 +216,12 @@ def uninstall(options):
     fstore.restore_all_files()
 
     try:
-        run(["/sbin/service", "nscd", "restart"])
+        service('nscd', 'restart')
     except:
         print "Failed to restart start the NSCD daemon"
 
     try:
-        run(["/sbin/chkconfig", "nscd", "on"])
+        chkconfig('nscd', 'on')
     except:
         print "Failed to configure automatic startup of the NSCD daemon"
 
@@ -328,14 +378,14 @@ def configure_certmonger(fstore, subject_base, cli_realm, options):
     started = True
 
     try:
-        run(["/sbin/service", "certmonger", "restart"])
+        service('certmonger', 'restart')
     except:
         print "Failed to start the certmonger daemon"
         print "Automatic certificate management will not be available"
         started = False
 
     try:
-        run(["/sbin/chkconfig", "certmonger", "on"])
+        chkconfig('certmonger', 'on')
     except:
         print "Failed to configure automatic startup of the certmonger daemon"
         print "Automatic certificate management will not be available"
@@ -624,14 +674,14 @@ def main():
 
     #Name Server Caching Daemon. Disable for SSSD, use otherwise
     try:
-        run(["/sbin/service", "nscd", nscd_action])
+        service('nscd', nscd_action)
     except:
         print "Failed to %s the NSCD daemon" % nscd_action
         if not options.sssd:
             print "Caching of users/groups will not be available"
 
     try:
-        run(["/sbin/chkconfig", "nscd", nscd_status])
+        chkconfig('nscd', nscd_status)
     except:
         print "Failed to configure automatic startup of the NSCD daemon"
         if not options.sssd: