dhcp: T3316: Adjust kea lease files' location and permissions

Move the kea lease file to a separate directory `/config/dhcp` that `kea`
process can write to so that subprocesses spawned by `kea` process can
operate on the lease files.

To allow `kea` process to write to `/config/dhcp`, add `_kea` user to
`vyattacfg` group. And the lease files are owned completely by `_kea`
user to play well with `kea-lfc` process.

Specifically, this is necessary for `kea-lfc` which is spawned by `kea`
process to clean up expired leases. Since `kea-lfc` creates additional
backup lease files, it needs write access to the lease file directory.

Additionally, change the extension of the lease file from `.leases` to
`.csv` to reflect the actual file format.

1 files changed, 1 insertions, 2 deletions

diff --git a/src/op_mode/clear_dhcp_lease.py b/src/op_mode/clear_dhcp_lease.py
index 2c95a2b08..7d4b47104 100755
--- a/src/op_mode/clear_dhcp_lease.py
+++ b/src/op_mode/clear_dhcp_lease.py
@@ -28,7 +28,7 @@ from vyos.utils.commit import commit_in_progress
 
 config = ConfigTreeQuery()
 base = ['service', 'dhcp-server']
-lease_file = '/config/dhcp4.leases'
+lease_file = '/config/dhcp/dhcp4-leases.csv'
 
 
 def del_lease_ip(address):
@@ -52,7 +52,6 @@ def is_ip_in_leases(address):
     Return True if address found in the lease file
     """
     leases = kea_parse_leases(lease_file)
-    lease_ips = []
     for lease in leases:
         if address == lease['address']:
             return True