Merge pull request #4237 from indrajitr/hostd-updateHEADcurrent

T6948: Keep DHCP server leases in sync with hostd records

1 files changed, 112 insertions, 0 deletions

diff --git a/src/system/sync-dhcp-lease-to-hosts.py b/src/system/sync-dhcp-lease-to-hosts.py
new file mode 100755
index 000000000..5c8b18faf
--- /dev/null
+++ b/src/system/sync-dhcp-lease-to-hosts.py
@@ -0,0 +1,112 @@
+#!/usr/bin/env python3
+#
+# Copyright (C) 2025 VyOS maintainers and contributors
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License version 2 or later as
+# published by the Free Software Foundation.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+import argparse
+import logging
+
+import vyos.opmode
+import vyos.hostsd_client
+
+from vyos.configquery import ConfigTreeQuery
+
+from vyos.kea import kea_get_active_config
+from vyos.kea import kea_get_dhcp_pools
+from vyos.kea import kea_get_server_leases
+
+# Configure logging
+logger = logging.getLogger(__name__)
+# set stream as output
+logs_handler = logging.StreamHandler()
+logger.addHandler(logs_handler)
+
+
+def _get_all_server_leases(inet_suffix='4') -> list:
+    mappings = []
+    try:
+        active_config = kea_get_active_config(inet_suffix)
+    except Exception:
+        raise vyos.opmode.DataUnavailable('Cannot fetch DHCP server configuration')
+
+    try:
+        pools = kea_get_dhcp_pools(active_config, inet_suffix)
+        mappings = kea_get_server_leases(
+            active_config, inet_suffix, pools, state=[], origin=None
+        )
+    except Exception:
+        raise vyos.opmode.DataUnavailable('Cannot fetch DHCP server leases')
+
+    return mappings
+
+
+if __name__ == '__main__':
+    # Parse command arguments
+    parser = argparse.ArgumentParser()
+    group = parser.add_mutually_exclusive_group(required=True)
+    group.add_argument('--inet', action='store_true', help='Use IPv4 DHCP leases')
+    group.add_argument('--inet6', action='store_true', help='Use IPv6 DHCP leases')
+    args = parser.parse_args()
+
+    inet_suffix = '4' if args.inet else '6'
+    service_suffix = '' if args.inet else 'v6'
+
+    if inet_suffix == '6':
+        raise vyos.opmode.UnsupportedOperation(
+            'Syncing IPv6 DHCP leases are not supported yet'
+        )
+
+    # Load configuration
+    config = ConfigTreeQuery()
+
+    # Check if DHCP server is configured
+    # Using warning instead of error since this check may fail during first-time
+    # DHCP server setup when the service is not yet configured in the config tree.
+    # This happens when called from systemd's ExecStartPost the first time.
+    if not config.exists(f'service dhcp{service_suffix}-server'):
+        logger.warning(f'DHCP{service_suffix} server is not configured')
+
+    # Check if hostfile-update is enabled
+    if not config.exists(f'service dhcp{service_suffix}-server hostfile-update'):
+        logger.debug(
+            f'Hostfile update is disabled for DHCP{service_suffix} server, skipping hosts update'
+        )
+        exit(0)
+
+    lease_data = _get_all_server_leases(inet_suffix)
+
+    try:
+        hc = vyos.hostsd_client.Client()
+
+        for mapping in lease_data:
+            ip_addr = mapping.get('ip')
+            mac_addr = mapping.get('mac')
+            name = mapping.get('hostname')
+            name = name if name else f'host-{mac_addr.replace(":", "-")}'
+            domain = mapping.get('domain')
+            fqdn = f'{name}.{domain}' if domain else name
+            hc.add_hosts(
+                {
+                    f'dhcp-server-{ip_addr}': {
+                        fqdn: {'address': [ip_addr], 'aliases': []}
+                    }
+                }
+            )
+
+        hc.apply()
+
+        logger.debug('Hosts store updated successfully')
+
+    except vyos.hostsd_client.VyOSHostsdError as e:
+        raise vyos.opmode.InternalError(str(e))