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Re: [jetty-users] is hot re-deployment without errors possible?
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Rob,
You could also look at customizing the
org.eclipse.jetty.server.handler.DefaultHandler, which is the last
handler in the HandlerCollection configured in jetty.xml. You could
make it do the error message, with an automatic retry redirect etc.
See http://download.eclipse.org/jetty/stable-9/xref/org/eclipse/jetty/server/handler/DefaultHandler.html
regards
Jan
On 22 March 2014 01:29, Rob Nikander <rob.nikander@xxxxxxxxx> wrote:
> Thanks for the help, I'll explore both of these suggestions.
>
> Rob
>
>
> On Mon, Mar 17, 2014 at 3:09 PM, "" <lord.buddha@xxxxxxxxx> wrote:
>>
>> Another way to avoid this really is to run two instances of jetty,
>> production and production-standby. You deploy your new application version
>> to the standby then tell your load balancer to send all requests without an
>> already established session to the standby instance which effectively makes
>> the standby production and the old production into a standby, This should
>> be possible with nginx but certainly is using other reverse proxy
>> arrangements.
>>
>> An advantage for this is that if your production and production-standby
>> use two different installations of jetty, then it will be much easier to
>> perform upgrades / maintenance of jetty. It also allows you to test your
>> new application on production-standy before letting customers at it.
>>
>> Of course, this requires a bit more sysadmin type effort.
>>
>>
>> On 17 March 2014 12:14, Jan Bartel <janb@xxxxxxxxxxx> wrote:
>>>
>>> Robert,
>>>
>>> A 404 seems pretty reasonable. If the connectors are still running,
>>> then the server is still accepting requests. Therefore there is a
>>> small amount of time during which the webapp is stopped, and the
>>> restart has not yet completed, and a request can arrive. During that
>>> period, it is correct that there is no context matching the request.
>>>
>>> If you want to avoid a 404 you could deploy a 2nd webapp at the same
>>> context path. When the 1st webapp stops due to the hot update, the 2nd
>>> webapp will answer the request. Normally this 2nd webapp would contain
>>> a static page with a maintenance message, maybe doing an automatic
>>> reload or directing the user to do the reload, and of course turning
>>> off caching. After you've got the 1st webapp redeployed, you can use
>>> jmx to turn off the 2nd webapp, so traffic will flow again to the 1st
>>> webapp.
>>>
>>> Jan
>>>
>>> On 15 March 2014 00:56, Robert Nikander <rob.nikander@xxxxxxxxx> wrote:
>>> > Upgrading to Jetty 9.1.3 fixed the NullPointerExceptions. But now,
>>> > instead of the 500 error, I get a 404 not found error for a second while the
>>> > app is redeploying. So, my question remains: is that normal, or is
>>> > re-deployment supposed to work seamlessly?
>>> >
>>> > Rob
>>> >
>>> >
>>> > On Mar 14, 2014, at 9:02 AM, Robert Nikander <rob.nikander@xxxxxxxxx>
>>> > wrote:
>>> >
>>> >> Ah, this may be fixed in newer Jetty versions. I'll try upgrading.
>>> >>
>>> >> https://bugs.eclipse.org/bugs/show_bug.cgi?id=417475
>>> >>
>>> >> Rob
>>> >>
>>> >> On Mar 14, 2014, at 8:49 AM, Robert Nikander <rob.nikander@xxxxxxxxx>
>>> >> wrote:
>>> >>
>>> >>> Jan,
>>> >>>
>>> >>> I believe the rsync is finished. I use a shell script and and the
>>> >>> two commands are sequential. Here is the script, and some log messages.
>>> >>>
>>> >>> #!/bin/bash
>>> >>> rsync -v myapp.war myserver:/opt/webapps
>>> >>> rsync -v deployment/myapp.xml myserver:/opt/jetty/webapps/
>>> >>>
>>> >>> If I run that, the logs show a stop and start.
>>> >>>
>>> >>> 2014-03-14 12:37:01.706:INFO:oejsh.ContextHandler:Scanner-0:
>>> >>> Stopped
>>> >>> o.e.j.w.WebAppContext@358ee631{/myapp,file:/tmp/jetty-0.0.0.0-8080-myapp.war-_myapp-any-/webapp/,UNAVAILABLE}{/myapp.war}
>>> >>> 2014-03-14 12:37:03.644:INFO:oejsh.ContextHandler:Scanner-0:
>>> >>> Started
>>> >>> o.e.j.w.WebAppContext@760aa0cd{/myapp,file:/tmp/jetty-0.0.0.0-8080-myapp.war-_myapp-any-/webapp/,AVAILABLE}{/myapp.war}
>>> >>>
>>> >>> I ran the script again, but this time kept reloading a page in the
>>> >>> browser, to trigger an error. Between the stop and the start messages, I
>>> >>> see a bunch of errors like this:
>>> >>>
>>> >>> 2014-03-14 12:37:33.079:WARN:oejs.HttpChannel:qtp121295574-906:
>>> >>> /myapp/static/common/angular/angular-sanitize.min.js
>>> >>> java.lang.NullPointerException
>>> >>> at
>>> >>> org.eclipse.jetty.server.handler.ContextHandlerCollection.handle(ContextHandlerCollection.java:192)
>>> >>> at
>>> >>> org.eclipse.jetty.server.handler.HandlerCollection.handle(HandlerCollection.java:109)
>>> >>> at
>>> >>> org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:97)
>>> >>> at
>>> >>> org.eclipse.jetty.rewrite.handler.RewriteHandler.handle(RewriteHandler.java:317)
>>> >>> at
>>> >>> org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:97)
>>> >>> at org.eclipse.jetty.server.Server.handle(Server.java:445)
>>> >>> at
>>> >>> org.eclipse.jetty.server.HttpChannel.handle(HttpChannel.java:268)
>>> >>> at
>>> >>> org.eclipse.jetty.server.HttpConnection.onFillable(HttpConnection.java:229)
>>> >>> at
>>> >>> org.eclipse.jetty.io.AbstractConnection$ReadCallback.run(AbstractConnection.java:358)
>>> >>> at
>>> >>> org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:601)
>>> >>> at
>>> >>> org.eclipse.jetty.util.thread.QueuedThreadPool$3.run(QueuedThreadPool.java:532)
>>> >>> at java.lang.Thread.run(Thread.java:744)
>>> >>>
>>> >>> Rob
>>> >>>
>>> >>>
>>> >>> On Mar 13, 2014, at 10:27 PM, Jan Bartel <janb@xxxxxxxxxxx> wrote:
>>> >>>
>>> >>>> Robert,
>>> >>>>
>>> >>>> Are you sure that the rsync has finished by the time you touch the
>>> >>>> xml file?
>>> >>>>
>>> >>>> Upgrading is generally a good idea :), but I can't think of anything
>>> >>>> specifically that would affect the hot redeployment (other than the
>>> >>>> war file not being fully copied).
>>> >>>>
>>> >>>> Might be able to comment more if you could post an example of the
>>> >>>> log messages.
>>> >>>>
>>> >>>> cheers
>>> >>>> Jan
>>> >>>>
>>> >>>> On 14 March 2014 02:33, Robert Nikander <rob.nikander@xxxxxxxxx>
>>> >>>> wrote:
>>> >>>>> Hi,
>>> >>>>>
>>> >>>>> (I posted on stackoverflow first [1] but no answers, so I'll try
>>> >>>>> here.)
>>> >>>>>
>>> >>>>> I have the usual web app deployer as described in the docs [2] and
>>> >>>>> defined in etc/jetty-deploy.xml. I use an xml file to define my web app
>>> >>>>> context, so when I push new code to my production server, I upload a new
>>> >>>>> myapp.war file using `rsync` and then touch that myapp.xml file. This works
>>> >>>>> pretty well, but there are few seconds where the app throws a
>>> >>>>> NullPointerException or other weirdness, and some users appear to be getting
>>> >>>>> corrupt statically served files (.js files from the war), so that they have
>>> >>>>> to flush their browser's cache for the app to work again.
>>> >>>>>
>>> >>>>> Is this supposed to work perfectly, or do you expect a brief dead
>>> >>>>> period like this? Is there a recommended way to deploy new code without the
>>> >>>>> 2-second snafu?
>>> >>>>>
>>> >>>>> Jetty is behind nginx with simple proxy configuration, if that
>>> >>>>> matters. I'm running 9.0.5, but could upgrade.
>>> >>>>>
>>> >>>>> thanks,
>>> >>>>> Rob
>>> >>>>>
>>> >>>>>
>>> >>>>> [1]
>>> >>>>> http://stackoverflow.com/questions/22357690/can-jetty-hot-redeployment-work-without-service-interruption
>>> >>>>> [2]
>>> >>>>> http://www.eclipse.org/jetty/documentation/current/hot-deployment.html
>>> >>>>> _______________________________________________
>>> >>>>> jetty-users mailing list
>>> >>>>> jetty-users@xxxxxxxxxxx
>>> >>>>> https://dev.eclipse.org/mailman/listinfo/jetty-users
>>> >>>>
>>> >>>>
>>> >>>>
>>> >>>> --
>>> >>>> Jan Bartel <janb@xxxxxxxxxxx>
>>> >>>> www.webtide.com
>>> >>>> 'Expert Jetty/CometD developer,production,operations advice'
>>> >>>> _______________________________________________
>>> >>>> jetty-users mailing list
>>> >>>> jetty-users@xxxxxxxxxxx
>>> >>>> https://dev.eclipse.org/mailman/listinfo/jetty-users
>>> >>>
>>> >>
>>> >
>>> > _______________________________________________
>>> > jetty-users mailing list
>>> > jetty-users@xxxxxxxxxxx
>>> > https://dev.eclipse.org/mailman/listinfo/jetty-users
>>>
>>>
>>>
>>> --
>>> Jan Bartel <janb@xxxxxxxxxxx>
>>> www.webtide.com
>>> 'Expert Jetty/CometD developer,production,operations advice'
>>> _______________________________________________
>>> jetty-users mailing list
>>> jetty-users@xxxxxxxxxxx
>>> https://dev.eclipse.org/mailman/listinfo/jetty-users
>>
>>
>>
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>
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--
Jan Bartel <janb@xxxxxxxxxxx>
www.webtide.com
'Expert Jetty/CometD developer,production,operations advice'
