GAE Java 8: need urlfetch to communicate between modules

[Bob Evans]

Hi,

After a bunch of experimentation I had to revert to the urlfetch handler ( <url-stream-handler>urlfetch</url-stream-handler>) because calling our backends  failed with a 302 redirect error. With the urlfetch handler, it works.

This seems wrong. Please tell me how I should properly design this.

Current design (has been working for years):

Frontend module gets https request forwards it to a backend module using UrlConnection and the doNotFollowRedirects=false.

Backend module is marked in web.xml CONFIDENTIAL and locked to admin role. Also, it checks the header for X-Google-Inbound-Appid to match our project.

After upgrading, it stopped working and the backend module sends a 302 redirect. 

If I add the  <url-stream-handler>urlfetch</url-stream-handler> to the frontend appengine-web.xml then it works again.

It looks like the native httpconnection in java 8 does not send the X-Google-Inbound-Appid header either.

Overall, how should one properly configure a backend module in the Java 8 environment to receive frontend connections yet keep it inaccessible from external queries?

Thanks for any help.

Bob

[Les Vogel]

[bcc: a googler]

Yes - we changed the behavior with the move to Java8 but left the work-a-round that you've found.  I don't believe the work-a-round will work w/ later versions of Java.

The current recommendation is that you create a JWT in one module and check it in the other.   See this Python example [rootdir].  I don't think there is a Java sample yet. (I saw the bug for it a few weeks ago).  

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•  Les Vogel   •  Cloud Developer Relations   •  le...@google.com   •  +1-408-676-7023