Unexplained Upstream Status Change: Online State Set to False

[ReiNichi]

First, I would like to apologize if this isn't the right place to ask for help and that my experience and knowledge isn't as deep for an sysadmin. Sadly, the main sysadmin is on vacation for two more weeks, so I'm unable to ask questions regarding the network.

Note: The following IPs and domains are made up.

I have the following situation. I have 5 shop servers: www1 - www5 with IPs 100.100.100.10 - 14. Each shop server hosts different shops via Apache for example, Shop A is on 100.100.100.10 and Shop B is on 100.100.100.11, etc. All requests go to my Zoraxy, which does not function as a load balancer but as a proxy. That is, in Zoraxy, I specify that requests to Shop B should be forwarded to the IP 100.100.100.11 using an upstream. Now, today I encountered the phenomenon that the upstream went offline. I found the following two lines in the logs:

[2025-09-16 09:55:28.918591] [uptime-monitor] [system:error] Ping upstream timeout. Assume offline: Get "https://100.100.100.10:80": context deadline exceeded (Client.Timeout exceeded while awaiting headers)

[2025-09-16 09:55:28.918623] [LoadBalancer] [system:info] Updating upstream 100.100.100.10:80 online state to false

As a result, numerous shops became inaccessible, as indicated by the following error message:

Failed to assign Upstream for this request: no online upstream is available for origin: www.URL-TO-SHOP.com

The domain www.URL-TO-SHOP.com was pointing to the above mentioned upstream in the error message (the 100.100.100.10:80)
Here is an example of one HTTP Proxy configuration in Zoraxy:

Fifteen minutes after the error shown above, I restarted Zoraxy via systemctl restart zoraxy, and five minutes later everything was working again.

Zoraxy is hosted on a Proxmox VM using Ubuntu.
Zoraxy Version is 3.1.9

Resulting questions:

• Is there any way to configure Zoraxy so that it doesn’t mark Upstreams as “down” after just a few failed checks?

• Is there any way to manually, preferably automatically, establish the connection to the Upstream after it's Online State was set to "false"?

• If I disable the “Upstream Monitoring” option in all HTTP Proxy entries that point to the same shop server, is it correct to assume Zoraxy will stop performing any uptime checks for that upstream?

• What are the specific details of the uptime check? i.e.

• How often is an uptime check performed?

• After how many failed checks (or how long of no response) does Zoraxy decide to mark an Upstream as offline?

[tobychui]

Yes, disabling the uptime monitor on a given rule will make Zoraxy skip checking if the upstream is offline.

The default uptime monitoring interval is 5 minutes per ping and will set it to offline if two consecutive checks timeout.

You can read more about the behavior details in the source code.