Merge pull request #1358 from sever-sever/T1237

routing: T1237: Add new feature failover route

1 files changed, 184 insertions, 0 deletions

diff --git a/src/helpers/vyos-failover.py b/src/helpers/vyos-failover.py
new file mode 100755
index 000000000..1ac193423
--- /dev/null
+++ b/src/helpers/vyos-failover.py
@@ -0,0 +1,184 @@
+#!/usr/bin/env python3
+#
+# Copyright (C) 2022 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 json
+import subprocess
+import socket
+import time
+
+from vyos.util import rc_cmd
+from pathlib import Path
+from systemd import journal
+
+
+my_name = Path(__file__).stem
+
+
+def get_best_route_options(route, debug=False):
+    """
+    Return current best route ('gateway, interface, metric)
+
+    % get_best_route_options('203.0.113.1')
+    ('192.168.0.1', 'eth1', 1)
+
+    % get_best_route_options('203.0.113.254')
+    (None, None, None)
+    """
+    rc, data = rc_cmd(f'ip --detail --json route show protocol failover {route}')
+    if rc == 0:
+        data = json.loads(data)
+        if len(data) == 0:
+            print(f'\nRoute {route} for protocol failover was not found')
+            return None, None, None
+        # Fake metric 999 by default
+        # Search route with the lowest metric
+        best_metric = 999
+        for entry in data:
+            if debug: print('\n', entry)
+            metric = entry.get('metric')
+            gateway = entry.get('gateway')
+            iface = entry.get('dev')
+            if metric < best_metric:
+                best_metric = metric
+                best_gateway = gateway
+                best_interface = iface
+        if debug:
+            print(f'### Best_route exists: {route}, best_gateway: {best_gateway}, '
+                  f'best_metric: {best_metric}, best_iface: {best_interface}')
+        return best_gateway, best_interface, best_metric
+
+def is_port_open(ip, port):
+    """
+    Check connection to remote host and port
+    Return True if host alive
+
+    % is_port_open('example.com', 8080)
+    True
+    """
+    s = socket.socket(socket.AF_INET, socket.SOCK_STREAM, socket.IPPROTO_TCP)
+    s.settimeout(2)
+    try:
+        s.connect((ip, int(port)))
+        s.shutdown(socket.SHUT_RDWR)
+        return True
+    except:
+        return False
+    finally:
+        s.close()
+
+def is_target_alive(target=None, iface='', proto='icmp', port=None, debug=False):
+    """
+    Host availability check by ICMP, ARP, TCP
+    Return True if target checks is successful
+
+    % is_target_alive('192.0.2.1', 'eth1', proto='arp')
+    True
+    """
+    if iface != '':
+        iface = f'-I {iface}'
+    if proto == 'icmp':
+        command = f'/usr/bin/ping -q {target} {iface} -n -c 2 -W 1'
+        rc, response = rc_cmd(command)
+        if debug: print(f'    [ CHECK-TARGET ]: [{command}] -- return-code [RC: {rc}]')
+        if rc == 0:
+            return True
+    elif proto == 'arp':
+        command = f'/usr/bin/arping -b -c 2 -f -w 1 -i 1 {iface} {target}'
+        rc, response = rc_cmd(command)
+        if debug: print(f'    [ CHECK-TARGET ]: [{command}] -- return-code [RC: {rc}]')
+        if rc == 0:
+            return True
+    elif proto == 'tcp' and port is not None:
+        return True if is_port_open(target, port) else False
+    else:
+        return False
+
+
+if __name__ == '__main__':
+    # Parse command arguments and get config
+    parser = argparse.ArgumentParser()
+    parser.add_argument('-c',
+                        '--config',
+                        action='store',
+                        help='Path to protocols failover configuration',
+                        required=True,
+                        type=Path)
+
+    args = parser.parse_args()
+    try:
+        config_path = Path(args.config)
+        config = json.loads(config_path.read_text())
+    except Exception as err:
+        print(
+            f'Configuration file "{config_path}" does not exist or malformed: {err}'
+        )
+        exit(1)
+
+    # Useful debug info to console, use debug = True
+    # sudo systemctl stop vyos-failover.service
+    # sudo /usr/libexec/vyos/vyos-failover.py --config /run/vyos-failover.conf
+    debug = False
+
+    while(True):
+
+        for route, route_config in config.get('route').items():
+
+            exists_route = exists_gateway, exists_iface, exists_metric =  get_best_route_options(route, debug=debug)
+
+            for next_hop, nexthop_config in route_config.get('next_hop').items():
+                conf_iface = nexthop_config.get('interface')
+                conf_metric = int(nexthop_config.get('metric'))
+                port = nexthop_config.get('check').get('port')
+                port_opt = f'port {port}' if port else ''
+                proto = nexthop_config.get('check').get('type')
+                target = nexthop_config.get('check').get('target')
+                timeout = nexthop_config.get('check').get('timeout')
+
+                # Best route not fonund in the current routing table
+                if exists_route == (None, None, None):
+                    if debug: print(f"    [NEW_ROUTE_DETECTED] route: [{route}]")
+                    # Add route if check-target alive
+                    if is_target_alive(target, conf_iface, proto, port, debug=debug):
+                        if debug: print(f'    [ ADD ] -- ip route add {route} via {next_hop} dev {conf_iface} '
+                                        f'metric {conf_metric} proto failover\n###')
+                        rc, command = rc_cmd(f'ip route add {route} via {next_hop} dev {conf_iface} '
+                                             f'metric {conf_metric} proto failover')
+                        # If something is wrong and gateway not added
+                        # Example: Error: Next-hop has invalid gateway.
+                        if rc !=0:
+                            if debug: print(f'{command} -- return-code [RC: {rc}] {next_hop} dev {conf_iface}')
+                        else:
+                            journal.send(f'ip route add {route} via {next_hop} dev {conf_iface} '
+                                         f'metric {conf_metric} proto failover', SYSLOG_IDENTIFIER=my_name)
+                    else:
+                        if debug: print(f'    [ TARGET_FAIL ] target checks fails for [{target}], do nothing')
+                        journal.send(f'Check fail for route {route} target {target} proto {proto} '
+                                     f'{port_opt}', SYSLOG_IDENTIFIER=my_name)
+
+                # Route was added, check if the target is alive
+                # We should delete route if check fails only if route exists in the routing table
+                if not is_target_alive(target, conf_iface, proto, port, debug=debug) and \
+                        exists_route != (None, None, None):
+                    if debug:
+                        print(f'Nexh_hop {next_hop} fail, target not response')
+                        print(f'    [ DEL ] -- ip route del {route} via {next_hop} dev {conf_iface} '
+                              f'metric {conf_metric} proto failover [DELETE]')
+                    rc_cmd(f'ip route del {route} via {next_hop} dev {conf_iface} metric {conf_metric} proto failover')
+                    journal.send(f'ip route del {route} via {next_hop} dev {conf_iface} '
+                                 f'metric {conf_metric} proto failover', SYSLOG_IDENTIFIER=my_name)
+
+                time.sleep(int(timeout))