T775: Add service config-sync between 2 routers

Service config-sync allows synchronizing a section of
the configuration.
As PoC allow only nat, nat66 and firewall sections

Rertreive the configuration for a section from self node and
send this configuration to the section of the 'secondary' node.

This feature adds a symlink from helper 'vyos_config_sync.py'
to '/config/scripts/commit/post-hooks.d' and config that is
located in '/run/config_sync_conf.conf'
It will synchronyze the config only if the setcion
was changed.

set service config-sync secondary address 192.0.2.11
set service config-sync secondary key xxx
set service config-sync section nat
set service config-sync section nat66
set service config-sync section firewall
set service config-sync mode load

3 files changed, 405 insertions, 0 deletions

diff --git a/interface-definitions/service-config-sync.xml.in b/interface-definitions/service-config-sync.xml.in
new file mode 100644
index 000000000..e804e17f7
--- /dev/null
+++ b/interface-definitions/service-config-sync.xml.in
@@ -0,0 +1,104 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<interfaceDefinition>
+  <node name="service">
+    <children>
+      <node name="config-sync" owner="${vyos_conf_scripts_dir}/service_config_sync.py">
+        <properties>
+          <help>Configuration synchronization</help>
+        </properties>
+        <children>
+          <node name="secondary">
+            <properties>
+              <help>Secondary server parameters</help>
+            </properties>
+            <children>
+              <leafNode name="address">
+                <properties>
+                  <help>IP address</help>
+                  <valueHelp>
+                    <format>ipv4</format>
+                    <description>IPv4 address to match</description>
+                  </valueHelp>
+                  <valueHelp>
+                    <format>ipv6</format>
+                    <description>IPv6 address to match</description>
+                  </valueHelp>
+                  <valueHelp>
+                    <format>hostname</format>
+                    <description>FQDN address to match</description>
+                  </valueHelp>
+                  <constraint>
+                    <validator name="ipv4-address"/>
+                    <validator name="ipv6-address"/>
+                    <validator name="fqdn"/>
+                  </constraint>
+                </properties>
+              </leafNode>
+              <leafNode name="timeout">
+                <properties>
+                  <help>Connection API timeout</help>
+                  <valueHelp>
+                    <format>u32:1-300</format>
+                    <description>Connection API timeout</description>
+                  </valueHelp>
+                  <constraint>
+                    <validator name="numeric" argument="--range 1-300"/>
+                  </constraint>
+                </properties>
+                <defaultValue>60</defaultValue>
+              </leafNode>
+              <leafNode name="key">
+                <properties>
+                  <help>HTTP API key</help>
+                </properties>
+              </leafNode>
+            </children>
+          </node>
+          <leafNode name="mode">
+            <properties>
+              <help>Synchronization mode</help>
+              <completionHelp>
+                <list>load set</list>
+              </completionHelp>
+              <valueHelp>
+                <format>load</format>
+                <description>Load and replace configuration section</description>
+              </valueHelp>
+              <valueHelp>
+                <format>set</format>
+                <description>Set configuration section</description>
+              </valueHelp>
+              <constraint>
+                <regex>(load|set)</regex>
+              </constraint>
+            </properties>
+          </leafNode>
+          <leafNode name="section">
+            <properties>
+              <help>Section for synchronization</help>
+              <completionHelp>
+                <list>nat nat66 firewall</list>
+              </completionHelp>
+              <valueHelp>
+                <format>nat</format>
+                <description>NAT</description>
+              </valueHelp>
+              <valueHelp>
+                <format>nat66</format>
+                <description>NAT66</description>
+              </valueHelp>
+              <valueHelp>
+                <format>firewall</format>
+                <description>firewall</description>
+              </valueHelp>
+              <constraint>
+                <regex>(nat|nat66|firewall)</regex>
+              </constraint>
+              <multi/>
+            </properties>
+          </leafNode>
+        </children>
+      </node>
+    </children>
+  </node>
+</interfaceDefinition>
diff --git a/src/conf_mode/service_config_sync.py b/src/conf_mode/service_config_sync.py
new file mode 100755
index 000000000..5cde735a1
--- /dev/null
+++ b/src/conf_mode/service_config_sync.py
@@ -0,0 +1,111 @@
+#!/usr/bin/env python3
+#
+# Copyright (C) 2023 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 os
+import json
+from pathlib import Path
+
+from vyos.config import Config
+from vyos.configdict import dict_merge
+from vyos.xml import defaults
+from vyos import ConfigError
+from vyos import airbag
+
+airbag.enable()
+
+
+service_conf = Path(f'/run/config_sync_conf.conf')
+post_commit_dir = '/run/scripts/commit/post-hooks.d'
+post_commit_file_src = '/usr/libexec/vyos/vyos_config_sync.py'
+post_commit_file = f'{post_commit_dir}/vyos_config_sync'
+
+
+def get_config(config=None):
+    if config:
+        conf = config
+    else:
+        conf = Config()
+
+    base = ['service', 'config-sync']
+    if not conf.exists(base):
+        return None
+    config = conf.get_config_dict(base,
+                                  get_first_key=True,
+                                  no_tag_node_value_mangle=True)
+
+    default_values = defaults(base)
+    config = dict_merge(default_values, config)
+
+    return config
+
+
+def verify(config):
+    # bail out early - looks like removal from running config
+    if not config:
+        return None
+
+    if 'mode' not in config:
+        raise ConfigError(f'config-sync mode is mandatory!')
+
+    for option in ['secondary', 'section']:
+        if option not in config:
+            raise ConfigError(f"config-sync '{option}' is not configured!")
+
+    if 'address' not in config['secondary']:
+        raise ConfigError(f'secondary address is mandatory!')
+    if 'key' not in config['secondary']:
+        raise ConfigError(f'secondary key is mandatory!')
+
+
+def generate(config):
+    if not config:
+
+        if os.path.exists(post_commit_file):
+            os.unlink(post_commit_file)
+
+        if service_conf.exists():
+            service_conf.unlink()
+
+        return None
+
+    # Write configuration file
+    conf_json = json.dumps(config, indent=4)
+    service_conf.write_text(conf_json)
+
+    # Create post commit dir
+    if not os.path.isdir(post_commit_dir):
+        os.makedirs(post_commit_dir)
+
+    # Symlink from helpers to post-commit
+    if not os.path.exists(post_commit_file):
+        os.symlink(post_commit_file_src, post_commit_file)
+
+    return None
+
+
+def apply(config):
+    return None
+
+
+if __name__ == '__main__':
+    try:
+        c = get_config()
+        verify(c)
+        generate(c)
+        apply(c)
+    except ConfigError as e:
+        print(e)
+        exit(1)
diff --git a/src/helpers/vyos_config_sync.py b/src/helpers/vyos_config_sync.py
new file mode 100755
index 000000000..6e66a6be0
--- /dev/null
+++ b/src/helpers/vyos_config_sync.py
@@ -0,0 +1,190 @@
+#!/usr/bin/env python3
+#
+# Copyright (C) 2023 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 os
+import json
+import requests
+import urllib3
+import logging
+from typing import Optional, List, Union, Dict, Any
+
+from vyos.config import Config
+
+
+CONFIG_FILE = '/run/config_sync_conf.conf'
+
+# Logging
+logging.basicConfig(level=logging.INFO)
+logger = logging.getLogger(__name__)
+logger.name = os.path.basename(__file__)
+
+# API
+API_HEADERS = {'Content-Type': 'application/json'}
+
+
+def post_request(url: str,
+                 data: str,
+                 headers: Dict[str, str]) -> requests.Response:
+    """Sends a POST request to the specified URL
+
+    Args:
+        url (str): The URL to send the POST request to.
+        data (Dict[str, Any]): The data to send with the POST request.
+        headers (Dict[str, str]): The headers to include with the POST request.
+
+    Returns:
+        requests.Response: The response object representing the server's response to the request
+    """
+
+    response = requests.post(url,
+                             data=data,
+                             headers=headers,
+                             verify=False,
+                             timeout=timeout)
+    return response
+
+
+def retrieve_config(section: str = None) -> Optional[Dict[str, Any]]:
+    """Retrieves the configuration from the local server.
+
+    Args:
+        section: str: The section of the configuration to retrieve. Default is None.
+
+    Returns:
+        Optional[Dict[str, Any]]: The retrieved configuration as a dictionary, or None if an error occurred.
+    """
+    if section is None:
+        section = []
+    else:
+        section = section.split()
+
+    conf = Config()
+    config = conf.get_config_dict(section, get_first_key=True)
+    if config:
+        return config
+    return None
+
+
+def set_remote_config(
+        address: str,
+        key: str,
+        op: str,
+        path: str = None,
+        section: Optional[str] = None) -> Optional[Dict[str, Any]]:
+    """Loads the VyOS configuration in JSON format to a remote host.
+
+    Args:
+        address (str): The address of the remote host.
+        key (str): The key to use for loading the configuration.
+        path (Optional[str]): The path of the configuration. Default is None.
+        section (Optional[str]): The section of the configuration to load. Default is None.
+
+    Returns:
+        Optional[Dict[str, Any]]: The response from the remote host as a dictionary, or None if an error occurred.
+    """
+
+    if path is None:
+        path = []
+    else:
+        path = path.split()
+    headers = {'Content-Type': 'application/json'}
+
+    # Disable the InsecureRequestWarning
+    urllib3.disable_warnings(urllib3.exceptions.InsecureRequestWarning)
+
+    url = f'https://{address}/configure-section'
+    data = json.dumps({
+        'op': mode,
+        'path': path,
+        'section': section,
+        'key': key
+    })
+
+    try:
+        config = post_request(url, data, headers)
+        return config.json()
+    except requests.exceptions.RequestException as e:
+        print(f"An error occurred: {e}")
+        logger.error(f"An error occurred: {e}")
+        return None
+
+
+def is_section_revised(section: str) -> bool:
+    from vyos.config_mgmt import is_node_revised
+    return is_node_revised([section])
+
+
+def config_sync(secondary_address: str,
+                secondary_key: str,
+                sections: List[str],
+                mode: str):
+    """Retrieve a config section from primary router in JSON format and send it to
+       secondary router
+    """
+    # Config sync only if sections changed
+    if not any(map(is_section_revised, sections)):
+        return
+
+    logger.info(
+        f"Config synchronization: Mode={mode}, Secondary={secondary_address}"
+    )
+
+    # Sync sections ("nat", "firewall", etc)
+    for section in sections:
+        config_json = retrieve_config(section=section)
+        # Check if config path deesn't exist, for example "set nat"
+        # we set empty value for config_json data
+        # As we cannot send to the remote host section "nat None" config
+        if not config_json:
+            config_json = ""
+        logger.debug(
+            f"Retrieved config for section '{section}': {config_json}")
+        set_config = set_remote_config(address=secondary_address,
+                                       key=secondary_key,
+                                       op=mode,
+                                       path=section,
+                                       section=config_json)
+        logger.debug(f"Set config for section '{section}': {set_config}")
+
+
+if __name__ == '__main__':
+    # Read configuration from file
+    if not os.path.exists(CONFIG_FILE):
+        logger.error(f"Post-commit: No config file '{CONFIG_FILE}' exists")
+        exit(0)
+
+    with open(CONFIG_FILE, 'r') as f:
+        config_data = f.read()
+
+    config = json.loads(config_data)
+
+    mode = config.get('mode')
+    secondary_address = config.get('secondary', {}).get('address')
+    secondary_key = config.get('secondary', {}).get('key')
+    sections = config.get('section')
+    timeout = int(config.get('secondary', {}).get('timeout'))
+
+    if not all([
+            mode, secondary_address, secondary_key, sections
+    ]):
+        logger.error(
+            "Missing required configuration data for config synchronization.")
+        exit(0)
+
+    config_sync(secondary_address, secondary_key,
+                sections, mode)