michaelneale mine are attached above.

twasink unfortunately can't see anything wrong with that specifically: https://gist.github.com/michaelneale/886148eb67749263e935156d1fe6acab is the snippet used on that server you tried. I am not sure what would make it decode but others have seen it.

AH:

http://stackoverflow.com/questions/20496963/avoid-nginx-decoding-query-parameters-on-proxy-pass-equivalent-to-allowencodeds/20544409#20544409
http://nginx.org/en/docs/http/ngx_http_proxy_module.html#proxy_pass

If the proxy_pass directive is specified with a URI, then when a request is passed to the server, the part of a normalized request URI matching the location is replaced by a URI specified in the directive:

location /name/ {
proxy_pass http://127.0.0.1/remote/;
}
If proxy_pass is specified without a URI, the request URI is passed to the server in the same form as sent by a client when the original request is processed, or the full normalized request URI is passed when processing the changed URI:
location /some/path/ {
proxy_pass http://127.0.0.1;
}

So to me this looks like the only difference, as you are proxying to /jenkins, it is normalising the URI for you (which is not wanted). I guess classic doesn't get hit by this (or does it?) as it always double encodes?

So if you change it to something like

location / {
    proxy_pass  http://tracking/webapp$request_uri;
}

then it should be passed verbatim, according to http://stackoverflow.com/questions/20496963/avoid-nginx-decoding-query-parameters-on-proxy-pass-equivalent-to-allowencodeds/20544409#20544409 (way too early in the morning for this).

Or have it proxy pass without a trailing uri component and it won't normalise for you.

Okay, so changing this, in my nginx jenkins.conf file:

location /jenkins/ {
  proxy_pass         http://jenkins:8080/jenkins/;
  ...
}

to this:

location /jenkins/ {
  proxy_pass         http://jenkins:8080;
  ...
}

worked.

Hmm - going back through the history of my config file, this is what I actually had at the start of my Jenkins/Nginx config. But then I wanted to run Jenkins on a subpath so I could put another web app (Sonatype Nexus) on the same server - and that's when I screwed it up. Weird.

twasink yes I think nginx is being odd here - many people asked about this (outside of jenkins) and been burnt by it, but they keep closing it as not a bug (I guess they have their reasons) - so not your screw up by any means. Bad UX from nginx that it subtly changes behavior ... you could keep the subpath if you use $request_uri if you still wanted to do that, should work.

nginx config fix.

When should it be released?

The ticket never appeared in the Blue Ocean release notes.

equincerot there is no fix on the blue ocean side - it requires a change to the config of the proxy (depends what is in use). 

Sorry Vivek for the assignee change. I misused JIRA shortcurts.

Indeed, michaelneale our configuration was having a "/" at the end of the proxy_pass. It has been changed and works fine now. Thanks!

equincerot great to hear. I have put a note to configuration in the wiki/documentation but even having this ticket is handy, as google seems to find it.