apache-frontend: Now monitor a re6St url (may be defined as a parameter)

software/apache-frontend/instance-apache-frontend.cfg

@@ -52,6 +52,7 @@ parts =
   monitor-backup-log-access
   monitor-ats-cache-stats-wrapper
   monitor-apache-configuration-verification
+  monitor-verify-re6st-connectivity
 
 extends = ${monitor-template:output}
 
@@ -629,3 +630,13 @@ mode = 0700
 command = echo "<pre>$($${apache-configuration:frontend-configuration-verification})</pre>"
 extra-context =
   key content :command
+
+[monitor-verify-re6st-connectivity]
+recipe = slapos.cookbook:check_url_available
+path = $${monitor-directory:monitor-custom-scripts}/re6st-connectivity
+url = $${public:re6st-verification-url}
+dash_path = ${dash:location}/bin/dash
+curl_path = ${curl:location}/bin/curl
+
+[public]
+re6st-verification-url = http://[2001:67c:1254:4::1]/index.html