From d3922f5c819dd9dea0bb7ac8a0108ab060df04f0 Mon Sep 17 00:00:00 2001
From: Paul Buetow <paul@buetow.org>
Date: Wed, 20 Mar 2024 18:37:39 +0200
Subject: add health-based DNS failover

---
 frontends/scripts/dns-failover.ksh | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

(limited to 'frontends/scripts')

diff --git a/frontends/scripts/dns-failover.ksh b/frontends/scripts/dns-failover.ksh
index 4042ee3..6566a5e 100644
--- a/frontends/scripts/dns-failover.ksh
+++ b/frontends/scripts/dns-failover.ksh
@@ -18,6 +18,21 @@ determine_master_and_standby () {
         standby=$tmp
     fi
 
+    local -i health_ok=1
+    if ! ftp -4 -o - https://$master/index.txt | grep "Welcome to $master"; then
+        echo "https://$master IPv4 health check failed"
+        health_ok=0
+    elif ! ftp -6 -o - https://$master/index.txt | grep "Welcome to $master"; then
+        echo "https://$master IPv6 health check failed"
+        health_ok=0
+    fi
+
+    if [ $health_ok -eq 0 ]; then
+        local tmp=$master
+        master=$standby
+        standby=$tmp
+    fi
+
     echo "Master is $master, standby is $standby"
 
     MASTER_A=$(host $master | awk '/has address/ { print $(NF) }')
-- 
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