From cb297aea56da91144c53be1f396b64a26a8e5b04 Mon Sep 17 00:00:00 2001
From: Viacheslav Hletenko <v.gletenko@vyos.io>
Date: Wed, 20 Sep 2023 07:34:36 +0000
Subject: T5602: Reverse-proxy add option backup for backend server

A `backup` server can be defined to take over in the case of all other
backends failing

set load-balancing reverse-proxy backend <tag> server <tag> address '192.0.2.3'
set load-balancing reverse-proxy backend <tag> server <tag> port '8883'
set load-balancing reverse-proxy backend <tag> server <tag> backup
---
 data/templates/load-balancing/haproxy.cfg.j2               | 2 +-
 interface-definitions/load-balancing-haproxy.xml.in        | 6 ++++++
 smoketest/scripts/cli/test_load_balancing_reverse_proxy.py | 2 ++
 3 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/data/templates/load-balancing/haproxy.cfg.j2 b/data/templates/load-balancing/haproxy.cfg.j2
index 0a40e1ecf..a75ee9904 100644
--- a/data/templates/load-balancing/haproxy.cfg.j2
+++ b/data/templates/load-balancing/haproxy.cfg.j2
@@ -146,7 +146,7 @@ backend {{ back }}
 {%         if back_config.server is vyos_defined %}
 {%             set ssl_back =  'ssl ca-file /run/haproxy/' ~ back_config.ssl.ca_certificate ~ '.pem' if back_config.ssl.ca_certificate is vyos_defined else '' %}
 {%             for server, server_config in back_config.server.items() %}
-    server {{ server }} {{ server_config.address }}:{{ server_config.port }}{{ ' check' if server_config.check is vyos_defined }}{{ ' send-proxy' if server_config.send_proxy is vyos_defined }}{{ ' send-proxy-v2' if server_config.send_proxy_v2 is vyos_defined }} {{ ssl_back }}
+    server {{ server }} {{ server_config.address }}:{{ server_config.port }}{{ ' check' if server_config.check is vyos_defined }}{{ ' backup' if server_config.backup is vyos_defined }}{{ ' send-proxy' if server_config.send_proxy is vyos_defined }}{{ ' send-proxy-v2' if server_config.send_proxy_v2 is vyos_defined }} {{ ssl_back }}
 {%             endfor %}
 {%         endif %}
 {%         if back_config.timeout.check is vyos_defined %}
diff --git a/interface-definitions/load-balancing-haproxy.xml.in b/interface-definitions/load-balancing-haproxy.xml.in
index f955a2fb7..564c335ec 100644
--- a/interface-definitions/load-balancing-haproxy.xml.in
+++ b/interface-definitions/load-balancing-haproxy.xml.in
@@ -124,6 +124,12 @@
                       </constraint>
                     </properties>
                   </leafNode>
+                  <leafNode name="backup">
+                    <properties>
+                      <help>Use backup server if other servers are not available</help>
+                      <valueless/>
+                    </properties>
+                  </leafNode>
                   <leafNode name="check">
                     <properties>
                       <help>Active health check backend server</help>
diff --git a/smoketest/scripts/cli/test_load_balancing_reverse_proxy.py b/smoketest/scripts/cli/test_load_balancing_reverse_proxy.py
index a33fd5c18..274b97f22 100755
--- a/smoketest/scripts/cli/test_load_balancing_reverse_proxy.py
+++ b/smoketest/scripts/cli/test_load_balancing_reverse_proxy.py
@@ -74,6 +74,7 @@ class TestLoadBalancingReverseProxy(VyOSUnitTestSHIM.TestCase):
         self.cli_set(back_base + [bk_second_name, 'mode', mode])
         self.cli_set(back_base + [bk_second_name, 'server', bk_second_name, 'address', bk_server_second])
         self.cli_set(back_base + [bk_second_name, 'server', bk_second_name, 'port', bk_server_port])
+        self.cli_set(back_base + [bk_second_name, 'server', bk_second_name, 'backup'])
 
         self.cli_set(base_path + ['global-parameters', 'max-connections', max_connections])
 
@@ -106,6 +107,7 @@ class TestLoadBalancingReverseProxy(VyOSUnitTestSHIM.TestCase):
         self.assertIn(f'backend {bk_second_name}', config)
         self.assertIn(f'mode {mode}', config)
         self.assertIn(f'server {bk_second_name} {bk_server_second}:{bk_server_port}', config)
+        self.assertIn(f'server {bk_second_name} {bk_server_second}:{bk_server_port} backup', config)
 
 
 if __name__ == '__main__':
-- 
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