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From Kurtis Rader <kra...@skepticism.us>
Subject Re: [users@httpd] Re: Proxying From Directory To App On Port
Date Fri, 28 Aug 2015 04:23:00 GMT
On Thu, Aug 27, 2015 at 8:21 PM, Steven Shi <steven200796@gmail.com> wrote:

> Hey Kurtis,
>
> I was in the middle of replying and then something clicked for me.  I
> spent the day today working on this one more time and ended up getting it
> working.  I believe my fundamental understanding of a proxy was simply
> incorrect.
>

> Your comment about the URI prefix was what made it click for me.
>

I am happy you solved your problem but am concerned you still do not really
understand what is happening.


> Basically all my requests on the client front end were formatted like so
> "/command".  I mistakenly thought that the client would run these with
> respect to the host it came from (Jetty returns the client as a result of
> the initial proxied GET to localhost:2000).  Apparently, the client ends up
> realizing it is no longer on localhost:2000 but is now instead on
> localhost:80 and was calling the requests as such.  This would also make
> sense why "/command" would result in the GET/POST URL as
> "localhost:80/command".
>

The client code running in the browser does not "realize" it is no longer
on localhost:2000.  At least not in the sense you seem to mean. The browser
client code is simply going (that is, making requests) where it was told to
go. Specifically, it appears (as I suspected) your Jetty backend has no
knowledge it is being proxied and is returning a response containing URIs
that implied the Jetty backend could be directly reached on port 80
(because the URIs in its response do not include a port number). When in
fact it can only be directly reached on port 2000. This is a very common
problem and why the ProxyReversePass directive in conjunction with
the proxy_html_module (or other suitable module) exists.

After your comment, I realized that requests also need to have the URI with
> respect to the original host rather than the proxy on localhost:2000.  As
> such I changed every instance of "/command" to "./command" and now
> everything works perfectly.
>

I don't understand what you did. For the benefit of myself, and everyone
else reading this email thread, can you provide more detail regarding what
your changed?


> I did in fact enable the high levels of debug output and could make no
> sense of them unfortunately...somehow one request ended up in 200 lines of
> garble (I cleared the log beforehand).
>

That is often the case. Which is why it is important to perform one
experiment at a time; i.e., issuing one client request then saving the log
files for analysis. If you do not minimize the number of variables (e.g.,
the number of unrelated HTTP requests) it can be very difficult to derive
any conclusions from the data.

-- 
Kurtis Rader
Caretaker of the exceptional canines Junior and Hank

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