Merge pull request #2774 from vyos/mergify/bp/sagitta/pr-2758

pki: T5886: add support for ACME protocol (LetsEncrypt) (backport #2758)

4 files changed, 197 insertions, 223 deletions

diff --git a/src/conf_mode/pki.py b/src/conf_mode/pki.py
index f7e14aa16..239e44c3b 100755
--- a/src/conf_mode/pki.py
+++ b/src/conf_mode/pki.py
@@ -1,6 +1,6 @@
 #!/usr/bin/env python3
 #
-# Copyright (C) 2021 VyOS maintainers and contributors
+# Copyright (C) 2021-2024 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
@@ -14,59 +14,66 @@
 # 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
+
+from sys import argv
 from sys import exit
 
 from vyos.config import Config
-from vyos.configdep import set_dependents, call_dependents
+from vyos.config import config_dict_merge
+from vyos.configdep import set_dependents
+from vyos.configdep import call_dependents
 from vyos.configdict import node_changed
+from vyos.configdiff import Diff
+from vyos.defaults import directories
 from vyos.pki import is_ca_certificate
 from vyos.pki import load_certificate
 from vyos.pki import load_public_key
 from vyos.pki import load_private_key
 from vyos.pki import load_crl
 from vyos.pki import load_dh_parameters
+from vyos.utils.boot import boot_configuration_complete
+from vyos.utils.dict import dict_search
 from vyos.utils.dict import dict_search_args
 from vyos.utils.dict import dict_search_recursive
+from vyos.utils.process import call
+from vyos.utils.process import cmd
+from vyos.utils.process import is_systemd_service_active
 from vyos import ConfigError
 from vyos import airbag
 airbag.enable()
 
-# keys to recursively search for under specified path, script to call if update required
+vyos_certbot_dir = directories['certbot']
+
+# keys to recursively search for under specified path
 sync_search = [
     {
         'keys': ['certificate'],
         'path': ['service', 'https'],
-        'script': '/usr/libexec/vyos/conf_mode/service_https.py'
     },
     {
         'keys': ['certificate', 'ca_certificate'],
         'path': ['interfaces', 'ethernet'],
-        'script': '/usr/libexec/vyos/conf_mode/interfaces_ethernet.py'
     },
     {
         'keys': ['certificate', 'ca_certificate', 'dh_params', 'shared_secret_key', 'auth_key', 'crypt_key'],
         'path': ['interfaces', 'openvpn'],
-        'script': '/usr/libexec/vyos/conf_mode/interfaces_openvpn.py'
     },
     {
         'keys': ['ca_certificate'],
         'path': ['interfaces', 'sstpc'],
-        'script': '/usr/libexec/vyos/conf_mode/interfaces_sstpc.py'
     },
     {
         'keys': ['certificate', 'ca_certificate', 'local_key', 'remote_key'],
         'path': ['vpn', 'ipsec'],
-        'script': '/usr/libexec/vyos/conf_mode/vpn_ipsec.py'
     },
     {
         'keys': ['certificate', 'ca_certificate'],
         'path': ['vpn', 'openconnect'],
-        'script': '/usr/libexec/vyos/conf_mode/vpn_openconnect.py'
     },
     {
         'keys': ['certificate', 'ca_certificate'],
         'path': ['vpn', 'sstp'],
-        'script': '/usr/libexec/vyos/conf_mode/vpn_sstp.py'
     }
 ]
 
@@ -82,6 +89,33 @@ sync_translate = {
     'crypt_key': 'openvpn'
 }
 
+def certbot_delete(certificate):
+    if not boot_configuration_complete():
+        return
+    if os.path.exists(f'{vyos_certbot_dir}/renewal/{certificate}.conf'):
+        cmd(f'certbot delete --non-interactive --config-dir {vyos_certbot_dir} --cert-name {certificate}')
+
+def certbot_request(name: str, config: dict, dry_run: bool=True):
+    # We do not call certbot when booting the system - there is no need to do so and
+    # request new certificates during boot/image upgrade as the certbot configuration
+    # is stored persistent under /config - thus we do not open the door to transient
+    # errors
+    if not boot_configuration_complete():
+        return
+
+    domains = '--domains ' + ' --domains '.join(config['domain_name'])
+    tmp = f'certbot certonly --non-interactive --config-dir {vyos_certbot_dir} --cert-name {name} '\
+          f'--standalone --agree-tos --no-eff-email --expand --server {config["url"]} '\
+          f'--email {config["email"]} --key-type rsa --rsa-key-size {config["rsa_key_size"]} '\
+          f'{domains}'
+    if 'listen_address' in config:
+        tmp += f' --http-01-address {config["listen_address"]}'
+    # verify() does not need to actually request a cert but only test for plausability
+    if dry_run:
+        tmp += ' --dry-run'
+
+    cmd(tmp, raising=ConfigError, message=f'ACME certbot request failed for "{name}"!')
+
 def get_config(config=None):
     if config:
         conf = config
@@ -93,25 +127,61 @@ def get_config(config=None):
                                      get_first_key=True,
                                      no_tag_node_value_mangle=True)
 
-    pki['changed'] = {}
+    if len(argv) > 1 and argv[1] == 'certbot_renew':
+        pki['certbot_renew'] = {}
+
     tmp = node_changed(conf, base + ['ca'], key_mangling=('-', '_'), recursive=True)
-    if tmp: pki['changed'].update({'ca' : tmp})
+    if tmp:
+        if 'changed' not in pki: pki.update({'changed':{}})
+        pki['changed'].update({'ca' : tmp})
 
     tmp = node_changed(conf, base + ['certificate'], key_mangling=('-', '_'), recursive=True)
-    if tmp: pki['changed'].update({'certificate' : tmp})
+    if tmp:
+        if 'changed' not in pki: pki.update({'changed':{}})
+        pki['changed'].update({'certificate' : tmp})
 
     tmp = node_changed(conf, base + ['dh'], key_mangling=('-', '_'), recursive=True)
-    if tmp: pki['changed'].update({'dh' : tmp})
+    if tmp:
+        if 'changed' not in pki: pki.update({'changed':{}})
+        pki['changed'].update({'dh' : tmp})
 
     tmp = node_changed(conf, base + ['key-pair'], key_mangling=('-', '_'), recursive=True)
-    if tmp: pki['changed'].update({'key_pair' : tmp})
+    if tmp:
+        if 'changed' not in pki: pki.update({'changed':{}})
+        pki['changed'].update({'key_pair' : tmp})
 
-    tmp = node_changed(conf, base + ['openvpn', 'shared-secret'], key_mangling=('-', '_'), recursive=True)
-    if tmp: pki['changed'].update({'openvpn' : tmp})
+    tmp = node_changed(conf, base + ['openvpn', 'shared-secret'], key_mangling=('-', '_'),
+                       recursive=True)
+    if tmp:
+        if 'changed' not in pki: pki.update({'changed':{}})
+        pki['changed'].update({'openvpn' : tmp})
 
     # We only merge on the defaults of there is a configuration at all
     if conf.exists(base):
-        pki = conf.merge_defaults(pki, recursive=True)
+        # We have gathered the dict representation of the CLI, but there are default
+        # options which we need to update into the dictionary retrived.
+        default_values = conf.get_config_defaults(**pki.kwargs, recursive=True)
+        # remove ACME default configuration if unused by CLI
+        if 'certificate' in pki:
+            for name, cert_config in pki['certificate'].items():
+                if 'acme' not in cert_config:
+                    # Remove ACME default values
+                    del default_values['certificate'][name]['acme']
+
+        # merge CLI and default dictionary
+        pki = config_dict_merge(default_values, pki)
+
+    # Certbot triggered an external renew of the certificates.
+    # Mark all ACME based certificates as "changed" to trigger
+    # update of dependent services
+    if 'certificate' in pki and 'certbot_renew' in pki:
+        renew = []
+        for name, cert_config in pki['certificate'].items():
+            if 'acme' in cert_config:
+                renew.append(name)
+        # If triggered externally by certbot, certificate key is not present in changed
+        if 'changed' not in pki: pki.update({'changed':{}})
+        pki['changed'].update({'certificate' : renew})
 
     # We need to get the entire system configuration to verify that we are not
     # deleting a certificate that is still referenced somewhere!
@@ -119,38 +189,34 @@ def get_config(config=None):
                                          get_first_key=True,
                                          no_tag_node_value_mangle=True)
 
-    if 'changed' in pki:
-        for search in sync_search:
-            for key in search['keys']:
-                changed_key = sync_translate[key]
-
-                if changed_key not in pki['changed']:
-                    continue
-
-                for item_name in pki['changed'][changed_key]:
-                    node_present = False
-                    if changed_key == 'openvpn':
-                        node_present = dict_search_args(pki, 'openvpn', 'shared_secret', item_name)
-                    else:
-                        node_present = dict_search_args(pki, changed_key, item_name)
-
-                    if node_present:
-                        search_dict = dict_search_args(pki['system'], *search['path'])
-
-                        if not search_dict:
-                            continue
-
-                        for found_name, found_path in dict_search_recursive(search_dict, key):
-                            if found_name == item_name:
-                                path = search['path']
-                                path_str = ' '.join(path + found_path)
-                                print(f'pki: Updating config: {path_str} {found_name}')
-
-                                if path[0] == 'interfaces':
-                                    ifname = found_path[0]
-                                    set_dependents(path[1], conf, ifname)
-                                else:
-                                    set_dependents(path[1], conf)
+    for search in sync_search:
+        for key in search['keys']:
+            changed_key = sync_translate[key]
+            if 'changed' not in pki or changed_key not in pki['changed']:
+                continue
+
+            for item_name in pki['changed'][changed_key]:
+                node_present = False
+                if changed_key == 'openvpn':
+                    node_present = dict_search_args(pki, 'openvpn', 'shared_secret', item_name)
+                else:
+                    node_present = dict_search_args(pki, changed_key, item_name)
+
+                if node_present:
+                    search_dict = dict_search_args(pki['system'], *search['path'])
+                    if not search_dict:
+                        continue
+                    for found_name, found_path in dict_search_recursive(search_dict, key):
+                        if found_name == item_name:
+                            path = search['path']
+                            path_str = ' '.join(path + found_path)
+                            print(f'PKI: Updating config: {path_str} {found_name}')
+
+                            if path[0] == 'interfaces':
+                                ifname = found_path[0]
+                                set_dependents(path[1], conf, ifname)
+                            else:
+                                set_dependents(path[1], conf)
 
     return pki
 
@@ -223,6 +289,22 @@ def verify(pki):
                 if not is_valid_private_key(private['key'], protected):
                     raise ConfigError(f'Invalid private key on certificate "{name}"')
 
+            if 'acme' in cert_conf:
+                if 'domain_name' not in cert_conf['acme']:
+                    raise ConfigError(f'At least one domain-name is required to request '\
+                                    f'certificate for "{name}" via ACME!')
+
+                if 'email' not in cert_conf['acme']:
+                    raise ConfigError(f'An email address is required to request '\
+                                    f'certificate for "{name}" via ACME!')
+
+                if 'certbot_renew' not in pki:
+                    # Only run the ACME command if something on this entity changed,
+                    # as this is time intensive
+                    tmp = dict_search('changed.certificate', pki)
+                    if tmp != None and name in tmp:
+                        certbot_request(name, cert_conf['acme'])
+
     if 'dh' in pki:
         for name, dh_conf in pki['dh'].items():
             if 'parameters' in dh_conf:
@@ -283,12 +365,58 @@ def generate(pki):
     if not pki:
         return None
 
+    # Certbot renewal only needs to re-trigger the services to load up the
+    # new PEM file
+    if 'certbot_renew' in pki:
+        return None
+
+    certbot_list = []
+    certbot_list_on_disk = []
+    if os.path.exists(f'{vyos_certbot_dir}/live'):
+        certbot_list_on_disk = [f.path.split('/')[-1] for f in os.scandir(f'{vyos_certbot_dir}/live') if f.is_dir()]
+
+    if 'certificate' in pki:
+        changed_certificates = dict_search('changed.certificate', pki)
+        for name, cert_conf in pki['certificate'].items():
+            if 'acme' in cert_conf:
+                certbot_list.append(name)
+                # generate certificate if not found on disk
+                if name not in certbot_list_on_disk:
+                    certbot_request(name, cert_conf['acme'], dry_run=False)
+                elif changed_certificates != None and name in changed_certificates:
+                    # when something for the certificate changed, we should delete it
+                    if name in certbot_list_on_disk:
+                        certbot_delete(name)
+                    certbot_request(name, cert_conf['acme'], dry_run=False)
+
+    # Cleanup certbot configuration and certificates if no longer in use by CLI
+    # Get foldernames under vyos_certbot_dir which each represent a certbot cert
+    if os.path.exists(f'{vyos_certbot_dir}/live'):
+        for cert in certbot_list_on_disk:
+            if cert not in certbot_list:
+                # certificate is no longer active on the CLI - remove it
+                certbot_delete(cert)
+
     return None
 
 def apply(pki):
+    systemd_certbot_name = 'certbot.timer'
     if not pki:
+        call(f'systemctl stop {systemd_certbot_name}')
         return None
 
+    has_certbot = False
+    if 'certificate' in pki:
+        for name, cert_conf in pki['certificate'].items():
+            if 'acme' in cert_conf:
+                has_certbot = True
+                break
+
+    if not has_certbot:
+        call(f'systemctl stop {systemd_certbot_name}')
+    elif has_certbot and not is_systemd_service_active(systemd_certbot_name):
+        call(f'systemctl restart {systemd_certbot_name}')
+
     if 'changed' in pki:
         call_dependents()
 
diff --git a/src/conf_mode/service_https.py b/src/conf_mode/service_https.py
index cb40acc9f..2e7ebda5a 100755
--- a/src/conf_mode/service_https.py
+++ b/src/conf_mode/service_https.py
@@ -22,7 +22,6 @@ from copy import deepcopy
 from time import sleep
 
 import vyos.defaults
-import vyos.certbot_util
 
 from vyos.base import Warning
 from vyos.config import Config
@@ -33,8 +32,6 @@ from vyos.pki import wrap_certificate
 from vyos.pki import wrap_private_key
 from vyos.template import render
 from vyos.utils.process import call
-from vyos.utils.process import is_systemd_service_running
-from vyos.utils.process import is_systemd_service_active
 from vyos.utils.network import check_port_availability
 from vyos.utils.network import is_listen_port_bind_service
 from vyos.utils.file import write_file
@@ -46,12 +43,11 @@ config_file = '/etc/nginx/sites-available/default'
 systemd_override = r'/run/systemd/system/nginx.service.d/override.conf'
 cert_dir = '/etc/ssl/certs'
 key_dir = '/etc/ssl/private'
-certbot_dir = vyos.defaults.directories['certbot']
 
 api_config_state = '/run/http-api-state'
 systemd_service = '/run/systemd/system/vyos-http-api.service'
 
-# https config needs to coordinate several subsystems: api, certbot,
+# https config needs to coordinate several subsystems: api,
 # self-signed certificate, as well as the virtual hosts defined within the
 # https config definition itself. Consequently, one needs a general dict,
 # encompassing the https and other configs, and a list of such virtual hosts
@@ -63,7 +59,6 @@ default_server_block = {
     'name'      : ['_'],
     'api'       : False,
     'vyos_cert' : {},
-    'certbot'   : False
 }
 
 def get_config(config=None):
@@ -80,7 +75,6 @@ def get_config(config=None):
 
     https = conf.get_config_dict(base, get_first_key=True, with_pki=True)
 
-    https['children_changed'] = diff.node_changed_children(base)
     https['api_add_or_delete'] = diff.node_changed_presence(base + ['api'])
 
     if 'api' not in https:
@@ -100,7 +94,6 @@ def get_config(config=None):
         http_api['vrf'] = conf.return_value(vrf_path)
 
     https['api'] = http_api
-
     return https
 
 def verify(https):
@@ -119,25 +112,17 @@ def verify(https):
             cert_name = certificates['certificate']
 
             if cert_name not in https['pki']['certificate']:
-                raise ConfigError("Invalid certificate on https configuration")
+                raise ConfigError('Invalid certificate on https configuration')
 
             pki_cert = https['pki']['certificate'][cert_name]
 
             if 'certificate' not in pki_cert:
-                raise ConfigError("Missing certificate on https configuration")
+                raise ConfigError('Missing certificate on https configuration')
 
             if 'private' not in pki_cert or 'key' not in pki_cert['private']:
                 raise ConfigError("Missing certificate private key on https configuration")
-
-        if 'certbot' in https['certificates']:
-            vhost_names = []
-            for _, vh_conf in https.get('virtual-host', {}).items():
-                vhost_names += vh_conf.get('server-name', [])
-            domains = https['certificates']['certbot'].get('domain-name', [])
-            domains_found = [domain for domain in domains if domain in vhost_names]
-            if not domains_found:
-                raise ConfigError("At least one 'virtual-host <id> server-name' "
-                              "matching the 'certbot domain-name' is required.")
+    else:
+        Warning('No certificate specified, using buildin self-signed certificates!')
 
     server_block_list = []
 
@@ -255,22 +240,6 @@ def generate(https):
         for block in server_block_list:
             block['vyos_cert'] = vyos_cert_data
 
-    # letsencrypt certificate using certbot
-
-    certbot = False
-    cert_domains = cert_dict.get('certbot', {}).get('domain-name', [])
-    if cert_domains:
-        certbot = True
-        for domain in cert_domains:
-            sub_list = vyos.certbot_util.choose_server_block(server_block_list,
-                                                             domain)
-            if sub_list:
-                for sb in sub_list:
-                    sb['certbot'] = True
-                    sb['certbot_dir'] = certbot_dir
-                    # certbot organizes certificates by first domain
-                    sb['certbot_domain_dir'] = cert_domains[0]
-
     if 'api' in list(https):
         vhost_list = https.get('api-restrict', {}).get('virtual-host', [])
         if not vhost_list:
@@ -283,7 +252,6 @@ def generate(https):
 
     data = {
         'server_block_list': server_block_list,
-        'certbot': certbot
     }
 
     render(config_file, 'https/nginx.default.j2', data)
@@ -297,27 +265,18 @@ def apply(https):
     https_service_name = 'nginx.service'
 
     if https is None:
-        if is_systemd_service_active(f'{http_api_service_name}'):
-            call(f'systemctl stop {http_api_service_name}')
+        call(f'systemctl stop {http_api_service_name}')
         call(f'systemctl stop {https_service_name}')
         return
 
-    if 'api' in https['children_changed']:
-        if 'api' in https:
-            if is_systemd_service_running(f'{http_api_service_name}'):
-                call(f'systemctl reload {http_api_service_name}')
-            else:
-                call(f'systemctl restart {http_api_service_name}')
-            # Let uvicorn settle before (possibly) restarting nginx
-            sleep(1)
-        else:
-            if is_systemd_service_active(f'{http_api_service_name}'):
-                call(f'systemctl stop {http_api_service_name}')
+    if 'api' in https:
+        call(f'systemctl reload-or-restart {http_api_service_name}')
+        # Let uvicorn settle before (possibly) restarting nginx
+        sleep(1)
+    else:
+        call(f'systemctl stop {http_api_service_name}')
 
-    if (not is_systemd_service_running(f'{https_service_name}') or
-        https['api_add_or_delete'] or
-        set(https['children_changed']) - set(['api'])):
-        call(f'systemctl restart {https_service_name}')
+    call(f'systemctl reload-or-restart {https_service_name}')
 
 if __name__ == '__main__':
     try:
diff --git a/src/conf_mode/service_https_certificates_certbot.py b/src/conf_mode/service_https_certificates_certbot.py
deleted file mode 100755
index 1a6a498de..000000000
--- a/src/conf_mode/service_https_certificates_certbot.py
+++ /dev/null
@@ -1,114 +0,0 @@
-#!/usr/bin/env python3
-#
-# Copyright (C) 2019-2020 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 sys
-import os
-
-import vyos.defaults
-from vyos.config import Config
-from vyos import ConfigError
-from vyos.utils.process import cmd
-from vyos.utils.process import call
-from vyos.utils.process import is_systemd_service_running
-
-from vyos import airbag
-airbag.enable()
-
-vyos_conf_scripts_dir = vyos.defaults.directories['conf_mode']
-vyos_certbot_dir = vyos.defaults.directories['certbot']
-
-dependencies = [
-    'service_https.py',
-]
-
-def request_certbot(cert):
-    email = cert.get('email')
-    if email is not None:
-        email_flag = '-m {0}'.format(email)
-    else:
-        email_flag = ''
-
-    domains = cert.get('domains')
-    if domains is not None:
-        domain_flag = '-d ' + ' -d '.join(domains)
-    else:
-        domain_flag = ''
-
-    certbot_cmd = f'certbot certonly --config-dir {vyos_certbot_dir} -n --nginx --agree-tos --no-eff-email --expand {email_flag} {domain_flag}'
-
-    cmd(certbot_cmd,
-        raising=ConfigError,
-        message="The certbot request failed for the specified domains.")
-
-def get_config():
-    conf = Config()
-    if not conf.exists('service https certificates certbot'):
-        return None
-    else:
-        conf.set_level('service https certificates certbot')
-
-    cert = {}
-
-    if conf.exists('domain-name'):
-        cert['domains'] = conf.return_values('domain-name')
-
-    if conf.exists('email'):
-        cert['email'] = conf.return_value('email')
-
-    return cert
-
-def verify(cert):
-    if cert is None:
-        return None
-
-    if 'domains' not in cert:
-        raise ConfigError("At least one domain name is required to"
-                          " request a letsencrypt certificate.")
-
-    if 'email' not in cert:
-        raise ConfigError("An email address is required to request"
-                          " a letsencrypt certificate.")
-
-def generate(cert):
-    if cert is None:
-        return None
-
-    # certbot will attempt to reload nginx, even with 'certonly';
-    # start nginx if not active
-    if not is_systemd_service_running('nginx.service'):
-        call('systemctl start nginx.service')
-
-    request_certbot(cert)
-
-def apply(cert):
-    if cert is not None:
-        call('systemctl restart certbot.timer')
-    else:
-        call('systemctl stop certbot.timer')
-        return None
-
-    for dep in dependencies:
-        cmd(f'{vyos_conf_scripts_dir}/{dep}', raising=ConfigError)
-
-if __name__ == '__main__':
-    try:
-        c = get_config()
-        verify(c)
-        generate(c)
-        apply(c)
-    except ConfigError as e:
-        print(e)
-        sys.exit(1)
diff --git a/src/conf_mode/vpn_ipsec.py b/src/conf_mode/vpn_ipsec.py
index 7fd32c230..5bdcf2fa1 100755
--- a/src/conf_mode/vpn_ipsec.py
+++ b/src/conf_mode/vpn_ipsec.py
@@ -43,6 +43,7 @@ from vyos.template import is_ipv4
 from vyos.template import is_ipv6
 from vyos.template import render
 from vyos.utils.network import is_ipv6_link_local
+from vyos.utils.network import interface_exists
 from vyos.utils.dict import dict_search
 from vyos.utils.dict import dict_search_args
 from vyos.utils.process import call
@@ -65,11 +66,11 @@ default_install_routes = 'yes'
 
 vici_socket = '/var/run/charon.vici'
 
-CERT_PATH = f'{swanctl_dir}/x509/'
+CERT_PATH   = f'{swanctl_dir}/x509/'
 PUBKEY_PATH = f'{swanctl_dir}/pubkey/'
-KEY_PATH  = f'{swanctl_dir}/private/'
-CA_PATH   = f'{swanctl_dir}/x509ca/'
-CRL_PATH  = f'{swanctl_dir}/x509crl/'
+KEY_PATH    = f'{swanctl_dir}/private/'
+CA_PATH     = f'{swanctl_dir}/x509ca/'
+CRL_PATH    = f'{swanctl_dir}/x509crl/'
 
 DHCP_HOOK_IFLIST = '/tmp/ipsec_dhcp_waiting'
 
@@ -394,7 +395,7 @@ def verify(ipsec):
 
                 if 'bind' in peer_conf['vti']:
                     vti_interface = peer_conf['vti']['bind']
-                    if not os.path.exists(f'/sys/class/net/{vti_interface}'):
+                    if not interface_exists(vti_interface):
                         raise ConfigError(f'VTI interface {vti_interface} for site-to-site peer {peer} does not exist!')
 
             if 'vti' not in peer_conf and 'tunnel' not in peer_conf: