T1277: [dhcp-server] bugfix 'show dhcp server leases'

The script did not check if the service was actually configured or not.
This caused a FileNotFoundError for unconfigured services.

  vyos@vyos:~$ show dhcp server leases
  Traceback (most recent call last):
    File "/usr/libexec/vyos/op_mode/show_dhcp.py", line 123, in <module>
      leases = get_leases(lease_file, state='active')
    File "/usr/libexec/vyos/op_mode/show_dhcp.py", line 60, in get_leases
      leases = IscDhcpLeases(lease_file).get()
    File "/usr/lib/python3/dist-packages/isc_dhcp_leases/iscdhcpleases.py", line 110, in get
      with open(self.filename) as lease_file:
  FileNotFoundError: [Errno 2] No such file or directory: '/config/dhcpd.leases'

(cherry picked from commit ed620ef7e8ba741e165698c558b110a31cc35dfd)

1 files changed, 8 insertions, 6 deletions

diff --git a/src/op_mode/show_dhcp.py b/src/op_mode/show_dhcp.py
index 0005d62a3..4c4ee6355 100755
--- a/src/op_mode/show_dhcp.py
+++ b/src/op_mode/show_dhcp.py
@@ -18,14 +18,12 @@
 import json
 import argparse
 import ipaddress
-
 import tabulate
+import sys
 
-import vyos.config
-
+from vyos.config import Config
 from isc_dhcp_leases import Lease, IscDhcpLeases
 
-
 lease_file = "/config/dhcpd.leases"
 pool_key = "shared-networkname"
 
@@ -110,6 +108,12 @@ if __name__ == '__main__':
 
     args = parser.parse_args()
 
+    # Do nothing if service is not configured
+    config = Config()
+    if not config.exists_effective('service dhcp-server'):
+        print("DHCP service is not configured")
+        sys.exit(0)
+
     if args.leases:
         if args.expired:
             if args.pool:
@@ -127,8 +131,6 @@ if __name__ == '__main__':
         else:
             show_leases(leases)
     elif args.statistics:
-        config = vyos.config.Config()
-
         pools = []
 
         # Get relevant pools