Move Pi-hole backup node from Serenity to NOMAD

pihole/nomad/keepalived.conf.template

@@ -0,0 +1,32 @@
+global_defs {
+    router_id ${ROUTER_ID_NAME}
+}
+
+vrrp_script chk_pihole_web {
+    script "grep -qi ':${PIHOLE_WEB_PORT_HEX}' /proc/net/tcp /proc/net/tcp6"
+    interval 2
+    fall 2
+    rise 2
+}
+
+vrrp_instance VI_DNS {
+    state ${KEEPALIVED_STATE}
+    interface ${LAN_INTERFACE}
+    virtual_router_id ${KEEPALIVED_ROUTER_ID}
+    priority ${KEEPALIVED_PRIORITY}
+    advert_int 1
+${NOPREEMPT_LINE}
+
+    authentication {
+        auth_type PASS
+        auth_pass ${KEEPALIVED_PASSWORD}
+    }
+
+    virtual_ipaddress {
+        ${VIP_CIDR}
+    }
+
+    track_script {
+        chk_pihole_web
+    }
+}