proxy and 502 responses

[sdouglass]

Hi, I have a question about Zimbra Proxy and intermittent 502 responses, different from the one in the other similarly named thread.

We have a setup similar to the one mentioned in the other thread: one proxy node and two mailbox nodes. We're using ZCS 5.0.9. We installed and configured the proxy according to the instructions at:

Working with Zimbra Proxy

We are seeing intermittent 502 responses, first noticed on the client side then seen in the nginx.access.log file. (The client in this case is a Java API that we wrote for posting to the Zimbra SOAP service, and this client has not changed in ~1 year).

I found bug 30999 about zmproxyinit leaving the proxy node in the list of route lookup targets. I looked at /opt/zimbra/conf/nginx/includes/nginx.conf.web and confirmed that the proxy node was in the route handler list. So I ran "zmprov ms proxynode.domain.com zimbraReverseProxyLookupTarget FALSE" and restarted the proxy. I looked at nginx.conf.web again and confirmed that the proxy was no longer in the list. However, we're still seeing the 502 responses.

I turned the nginx logging level to debug and restarted the proxy, and I'm seeing log messages in nginx.log, corresponding to the 502 responses. The logs contain this message:

2009/01/07 13:18:08 [error] 28405#0: *151115 no live upstreams while connecting to upstream, client: 10.1.2.62, server: proxynode.domain.com, URL: "/service/soap", upstream: "http://zimbra/service/soap", host: "proxynode.domain.com"

Has anyone seen anything like this or have any idea what might be going on here?