Stale-While-Revalidate or Similar
Graham Lyons
graham.lyons at bbc.co.uk
Tue Mar 20 11:16:32 CET 2012
Yeah, you want grace mode:
https://www.varnish-cache.org/docs/trunk/tutorial/handling_misbehaving_servers.html#grace-mode
As it says on that page, "it serves stale content to avoid request pile-up."
On 20 Mar 2012, at 10:06, varnish-misc-request at varnish-cache.org wrote:
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>
> Today's Topics:
>
> 1. Re: Stale-While-Revalidate or Similar (Graham Lyons)
> 2. Re: Stale-While-Revalidate or Similar (Michael Borejdo)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Tue, 20 Mar 2012 09:50:54 +0000
> From: Graham Lyons <graham.lyons at bbc.co.uk>
> To: varnish-misc at varnish-cache.org
> Subject: Re: Stale-While-Revalidate or Similar
> Message-ID: <9303601D-DC59-45DA-BCCB-6B0D3621557E at bbc.co.uk>
> Content-Type: text/plain; charset="us-ascii"
>
> Hi Michael,
>
> There is a similar feature to this available in Varnish:
> https://www.varnish-cache.org/docs/trunk/tutorial/handling_misbehaving_servers.html
>
> Grace and saint modes correspond roughly, respectively to stale-while-revalidate and stale-if-error proposed in RFC5861.
>
> Graham.
>
> On 20 Mar 2012, at 09:24, varnish-misc-request at varnish-cache.org wrote:
>
>> Send varnish-misc mailing list submissions to
>> varnish-misc at varnish-cache.org
>>
>> To subscribe or unsubscribe via the World Wide Web, visit
>> https://www.varnish-cache.org/lists/mailman/listinfo/varnish-misc
>> or, via email, send a message with subject or body 'help' to
>> varnish-misc-request at varnish-cache.org
>>
>> You can reach the person managing the list at
>> varnish-misc-owner at varnish-cache.org
>>
>> When replying, please edit your Subject line so it is more specific
>> than "Re: Contents of varnish-misc digest..."
>>
>>
>> Today's Topics:
>>
>> 1. Re: Varnish client IP address not display (MassiveScale.net)
>> 2. VUG5 Paris BOF (Jonathan Matthews)
>> 3. Re: Communication between Varnish and the Backend (Hugues Alary)
>> 4. using the max-age request header (Jeroen Ooms)
>> 5. Re: Communication between Varnish and the Backend (Per Buer)
>> 6. Stale-While-Revalidate or Similar (Michael Borejdo)
>>
>>
>> ----------------------------------------------------------------------
>>
>> Message: 1
>> Date: Mon, 19 Mar 2012 12:39:36 +0100
>> From: "MassiveScale.net" <info at massivescale.net>
>> To: varnish-misc at varnish-cache.org
>> Subject: Re: Varnish client IP address not display
>> Message-ID: <4F671AF8.3060201 at massivescale.net>
>> Content-Type: text/plain; charset=ISO-8859-1
>>
>> On 03/19/2012 09:02 AM, Stewart Robinson wrote:
>>> Jewel,
>>> What header are you checking on the back end?
>>> You should be reading the x-forwarded-for header rather than some form
>>> of remote_addr.
>>
>> Alternatively, if your backend server is Apache, you could use mod_rpaf
>> http://stderr.net/apache/rpaf/
>>
>> --
>> Andrzej Godziuk
>> http://MassiveScale.net/
>>
>>
>>
>> ------------------------------
>>
>> Message: 2
>> Date: Mon, 19 Mar 2012 13:25:22 +0000
>> From: Jonathan Matthews <contact at jpluscplusm.com>
>> To: varnish-misc at varnish-cache.org
>> Subject: VUG5 Paris BOF
>> Message-ID:
>> <CAKsTx7Dv1rf62dJ6XYMo0n+vcB02nP7fyxX9CcPaPw2KbHUD-Q at mail.gmail.com>
>> Content-Type: text/plain; charset=UTF-8
>>
>> Hi all -
>>
>> I'm heading along to VUG5 this week - really looking forward to
>> meeting a lot of you and seeing how you're using and abusing our
>> favourite tool :-)
>>
>> When I signed up, I don't recall ticking the "BOF" checkbox - could
>> anyone let me know if it's too late to get in on that action?
>>
>> Either way, are people (like me) who are attending *just* the user day
>> (Thursday) perhaps looking for more Varnish chat on the Friday or the
>> weekend? I'm there 'til Sunday, and would love to get the most out of
>> a high concentration of Varnish-literate folk!
>>
>> All the best,
>> Jonathan
>> --
>> Jonathan Matthews
>> London, Oxford, UK
>> http://www.jpluscplusm.com/contact.html
>>
>>
>>
>> ------------------------------
>>
>> Message: 3
>> Date: Mon, 19 Mar 2012 12:50:23 -0700
>> From: Hugues Alary <hugues.alary at gmail.com>
>> To: varnish-misc at varnish-cache.org
>> Subject: Re: Communication between Varnish and the Backend
>> Message-ID:
>> <CAN-YAk8S=dCxUXR5GbyC3+s3oSgis0+doetcw0N8QUGPJ1Mteg at mail.gmail.com>
>> Content-Type: text/plain; charset="iso-8859-1"
>>
>> Happy Monday everybody,
>>
>> Nobody, got some good advices for me? :)
>>
>> Thanks,
>> -Hugues
>>
>> On Fri, Mar 16, 2012 at 3:42 PM, Hugues Alary <hugues.alary at gmail.com>wrote:
>>
>>> Hi everybody,
>>>
>>> I'm configuring varnish to be used with my web application.
>>>
>>> I need my backend to be able to give instructions to Varnish depending on
>>> the page requested. For example, some of my pages contain ESI includes,
>>> some don't.
>>>
>>> I want my application to tell varnish wether or not do the esi
>>> processing. This approach allows me to keep my VCL configuration file
>>> abstracted from the application. I can then redistribute the VCL to other
>>> users and let their application control the cache.
>>>
>>> So far my solution is to instruct varnish via HTTP headers.
>>>
>>> In my current example I set a header X-Application-DoEsi to 1 or 0. When
>>> varnish receives the response from the backend, it looks for the value
>>> of X-Application-DoEsi and does or not the ESI processing.
>>>
>>> - I was wondering if communicating with varnish via HTTP header is a
>>> good solution?
>>> - How bad can it be performance wise?
>>> - Should I be worried about security (interception/modification of the
>>> communication between Varnish and the backend), even if no credential will
>>> never be sent through HTTP headers? (Also, currently Varnish and the
>>> backend are on the same machine, but chances are that they will in the
>>> future not live on the same host).
>>>
>>> In the future, I plan on instructing varnish not to cache certain pages
>>> containing user defined query strings. I want the user to be able to
>>> specify these un-cachable urls query strings directly in the application.
>>> The application will then send the un-cachable query strings in a header
>>> X-Application-QueryStringNoCache: "querystring1,querystring2,...".
>>>
>>> Is that a bad idea?
>>>
>>> Thank you for your help!
>>>
>>> --
>>> Hugues ALARY
>>>
>>
>>
>>
>> --
>> Hugues ALARY
>> -------------- next part --------------
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>> URL: <https://www.varnish-cache.org/lists/pipermail/varnish-misc/attachments/20120319/a5ee34d6/attachment-0001.html>
>>
>> ------------------------------
>>
>> Message: 4
>> Date: Mon, 19 Mar 2012 17:11:57 -0700
>> From: Jeroen Ooms <jeroen.ooms at stat.ucla.edu>
>> To: varnish-misc at varnish-cache.org
>> Subject: using the max-age request header
>> Message-ID:
>> <CABFfbXtVc3vMVB-7_vEUZW6fXup5zte6rVhwL7avsQdqHX1ZHQ at mail.gmail.com>
>> Content-Type: text/plain; charset=ISO-8859-1
>>
>> How do I configure my VLC to let Varnish respect the 'Cache-Control
>> max-age' request header? Someone on SO suggested the following:
>>
>> if (req.http.Cache-Control ~ '\bmax-age=\b`) {
>> if (std.duration(regsub(req.http.Cache-Control,
>> ".*\bmax-age=(\d+)\b.*", "\1s"), 0s) < obj.age) {
>> return (pass);
>> }
>> }
>>
>> However, what I don't like about this is that vcl_pass does not
>> actually update the cache with the new entry. How can I configure it
>> so that when max age < obj.age, a fresh copy will be fetched and
>> inserted into cache?
>>
>>
>>
>> ------------------------------
>>
>> Message: 5
>> Date: Tue, 20 Mar 2012 07:25:05 +0100
>> From: Per Buer <perbu at varnish-software.com>
>> To: Hugues Alary <hugues.alary at gmail.com>
>> Cc: varnish-misc at varnish-cache.org
>> Subject: Re: Communication between Varnish and the Backend
>> Message-ID:
>> <CAOXZevDAcWRxDFbUA_mSh4_Hh2S1ukF9PGbmN6X2UThC-Md+5Q at mail.gmail.com>
>> Content-Type: text/plain; charset="iso-8859-1"
>>
>> On Fri, Mar 16, 2012 at 11:42 PM, Hugues Alary <hugues.alary at gmail.com>wrote:
>> (..)
>>
>>>
>>> - I was wondering if communicating with varnish via HTTP header is a
>>> good solution?
>>>
>>> Yes.
>>
>>>
>>> - How bad can it be performance wise?
>>>
>>> Negligible.
>>
>>
>>>
>>> - Should I be worried about security (interception/modification of the
>>> communication between Varnish and the backend), even if no credential will
>>> never be sent through HTTP headers? (Also, currently Varnish and the
>>> backend are on the same machine, but chances are that they will in the
>>> future not live on the same host).
>>>
>>>
>> It's more or less impossible to turn Varnish into an open proxy so I
>> wouldn't worry about that.
>>
>>
>>>
>>>
>>> In the future, I plan on instructing varnish not to cache certain pages
>>> containing user defined query strings. I want the user to be able to
>>> specify these un-cachable urls query strings directly in the application.
>>> The application will then send the un-cachable query strings in a header
>>> X-Application-QueryStringNoCache: "querystring1,querystring2,...".
>>>
>>> Is that a bad idea?
>>>
>>
>> No. If it works for you then go for it.
>>
>>
>> --
>> Per Buer, CEO
>> Phone: +47 21 98 92 61 / Mobile: +47 958 39 117 / Skype: per.buer
>> *Varnish makes websites fly!*
>> Whitepapers <http://www.varnish-software.com/whitepapers> |
>> Video<http://www.youtube.com/watch?v=x7t2Sp174eI> |
>> Twitter <https://twitter.com/varnishsoftware>
>> -------------- next part --------------
>> An HTML attachment was scrubbed...
>> URL: <https://www.varnish-cache.org/lists/pipermail/varnish-misc/attachments/20120320/59e9f0ef/attachment-0001.html>
>>
>> ------------------------------
>>
>> Message: 6
>> Date: Tue, 20 Mar 2012 09:24:02 +0000
>> From: Michael Borejdo <mib at electronic-minds.de>
>> To: "varnish-misc at varnish-cache.org" <varnish-misc at varnish-cache.org>
>> Subject: Stale-While-Revalidate or Similar
>> Message-ID:
>> <BE4EDDBE2C55604EB9F3EBA421CB227A23971439 at EM-MBX-1.electronic-minds.local>
>>
>> Content-Type: text/plain; charset="us-ascii"
>>
>> Hello List,
>>
>> Is there support for something like "stale-while-revalidate" coming to Varnish?
>> I need to make the request to my backend-servers async and serve slightly stale content (defined by grace) and I do not want a user to wait for the backend at any time.
>> Or is there any other way with using vcl trickery to accomplish this?
>> (Unfortunately I cannot seem to find any info on this topic and the thread I found on the list has not been answered) [1]
>>
>> [1] https://www.varnish-cache.org/lists/pipermail/varnish-misc/2012-February/021644.html
>>
>> Thanks
>>
>> Michael
>> -------------- next part --------------
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>>
>> ------------------------------
>>
>> _______________________________________________
>> varnish-misc mailing list
>> varnish-misc at varnish-cache.org
>> https://www.varnish-cache.org/lists/mailman/listinfo/varnish-misc
>>
>> End of varnish-misc Digest, Vol 72, Issue 21
>> ********************************************
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>
> ------------------------------
>
> Message: 2
> Date: Tue, 20 Mar 2012 10:06:04 +0000
> From: Michael Borejdo <mib at electronic-minds.de>
> To: "varnish-misc at varnish-cache.org" <varnish-misc at varnish-cache.org>
> Subject: Re: Stale-While-Revalidate or Similar
> Message-ID:
> <BE4EDDBE2C55604EB9F3EBA421CB227A2397145E at EM-MBX-1.electronic-minds.local>
>
> Content-Type: text/plain; charset="iso-8859-1"
>
> Hi there,
>
>> There is a similar feature to this available in Varnish:
>> https://www.varnish-cache.org/docs/trunk/tutorial/handling_misbehaving_servers.html
>
> Unfortunately my servers are healthy (they do not send 5XX or the like), but are just slow as hell sometimes.
> Or how is "health" "measured" by varnish?
>
> I think this solution will not work for me, since my backend seems to be healthy.
> What I basically want to accomplish is to prevent "the poor sod" from waiting for a request. Stale content is acceptable, waiting isn't.
>
> Thanks
>
> Michael
>
> ---------------------------------------------------------------
> Von: varnish-misc-bounces at varnish-cache.org [mailto:varnish-misc-bounces at varnish-cache.org] Im Auftrag von Graham Lyons
> Gesendet: Dienstag, 20. M?rz 2012 10:51
> An: varnish-misc at varnish-cache.org
> Betreff: Re: Stale-While-Revalidate or Similar
>
> Hi Michael,
>
> There is a similar feature to this available in Varnish:
> https://www.varnish-cache.org/docs/trunk/tutorial/handling_misbehaving_servers.html
>
> Grace and saint modes correspond roughly, respectively to stale-while-revalidate and stale-if-error proposed in RFC5861.
>
> Graham.
>
> On 20 Mar 2012, at 09:24, varnish-misc-request at varnish-cache.org wrote:
>
>
> Send varnish-misc mailing list submissions to
> varnish-misc at varnish-cache.org
>
> To subscribe or unsubscribe via the World Wide Web, visit
> https://www.varnish-cache.org/lists/mailman/listinfo/varnish-misc
> or, via email, send a message with subject or body 'help' to
> varnish-misc-request at varnish-cache.org
>
> You can reach the person managing the list at
> varnish-misc-owner at varnish-cache.org
>
> When replying, please edit your Subject line so it is more specific
> than "Re: Contents of varnish-misc digest..."
>
>
> Today's Topics:
>
> ??1. Re: Varnish client IP address not display (MassiveScale.net)
> ??2. VUG5 Paris BOF (Jonathan Matthews)
> ??3. Re: Communication between Varnish and the Backend (Hugues Alary)
> ??4. using the max-age request header (Jeroen Ooms)
> ??5. Re: Communication between Varnish and the Backend (Per Buer)
> ??6. Stale-While-Revalidate or Similar (Michael Borejdo)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Mon, 19 Mar 2012 12:39:36 +0100
> From: "MassiveScale.net" <info at massivescale.net>
> To: varnish-misc at varnish-cache.org
> Subject: Re: Varnish client IP address not display
> Message-ID: <4F671AF8.3060201 at massivescale.net>
> Content-Type: text/plain; charset=ISO-8859-1
>
> On 03/19/2012 09:02 AM, Stewart Robinson wrote:
>
> Jewel,
> What header are you checking on the back end?
> You should be reading the x-forwarded-for header rather than some form
> of remote_addr.
>
> Alternatively, if your backend server is Apache, you could use mod_rpaf
> http://stderr.net/apache/rpaf/
>
> --
> Andrzej Godziuk
> http://MassiveScale.net/
>
>
>
> ------------------------------
>
> Message: 2
> Date: Mon, 19 Mar 2012 13:25:22 +0000
> From: Jonathan Matthews <contact at jpluscplusm.com>
> To: varnish-misc at varnish-cache.org
> Subject: VUG5 Paris BOF
> Message-ID:
> <CAKsTx7Dv1rf62dJ6XYMo0n+vcB02nP7fyxX9CcPaPw2KbHUD-Q at mail.gmail.com>
> Content-Type: text/plain; charset=UTF-8
>
> Hi all -
>
> I'm heading along to VUG5 this week - really looking forward to
> meeting a lot of you and seeing how you're using and abusing our
> favourite tool :-)
>
> When I signed up, I don't recall ticking the "BOF" checkbox - could
> anyone let me know if it's too late to get in on that action?
>
> Either way, are people (like me) who are attending *just* the user day
> (Thursday) perhaps looking for more Varnish chat on the Friday or the
> weekend? I'm there 'til Sunday, and would love to get the most out of
> a high concentration of Varnish-literate folk!
>
> All the best,
> Jonathan
> --
> Jonathan Matthews
> London, Oxford, UK
> http://www.jpluscplusm.com/contact.html
>
>
>
> ------------------------------
>
> Message: 3
> Date: Mon, 19 Mar 2012 12:50:23 -0700
> From: Hugues Alary <hugues.alary at gmail.com>
> To: varnish-misc at varnish-cache.org
> Subject: Re: Communication between Varnish and the Backend
> Message-ID:
> <CAN-YAk8S=dCxUXR5GbyC3+s3oSgis0+doetcw0N8QUGPJ1Mteg at mail.gmail.com>
> Content-Type: text/plain; charset="iso-8859-1"
>
> Happy Monday everybody,
>
> Nobody, got some good advices for me? :)
>
> Thanks,
> -Hugues
>
> On Fri, Mar 16, 2012 at 3:42 PM, Hugues Alary <hugues.alary at gmail.com>wrote:
>
>
> Hi everybody,
>
> I'm configuring varnish to be used with my web application.
>
> I need my backend to be able to give instructions to Varnish depending on
> the page requested. For example, some of my pages contain ESI includes,
> some don't.
>
> I want my application to tell varnish wether or not do the esi
> processing. This approach allows me to keep my VCL configuration file
> abstracted from the application. I can then redistribute the VCL to other
> users and let their application control the cache.
>
> So far my solution is to instruct varnish via HTTP headers.
>
> In my current example I set a header X-Application-DoEsi to 1 or 0. When
> varnish receives the response from the backend, it looks for the value
> of X-Application-DoEsi and does or not the ESI processing.
>
> ??- I was wondering if communicating with varnish via HTTP header is a
> ??good solution?
> ??- How bad can it be performance wise?
> ??- Should I be worried about security (interception/modification of the
> ??communication between Varnish and the backend), even if no credential will
> ??never be sent through HTTP headers? (Also, currently Varnish and the
> ??backend are on the same machine, but chances are that they will in the
> ??future not live on the same host).
>
> In the future, I plan on instructing varnish not to cache certain pages
> containing user defined query strings. I want the user to be able to
> specify these un-cachable urls query strings directly in the application.
> The application will then send the un-cachable query strings in a header
> X-Application-QueryStringNoCache: "querystring1,querystring2,...".
>
> Is that a bad idea?
>
> Thank you for your help!
>
> --
> Hugues ALARY
>
>
>
>
> --
> Hugues ALARY
> -------------- next part --------------
> An HTML attachment was scrubbed...
> URL: <https://www.varnish-cache.org/lists/pipermail/varnish-misc/attachments/20120319/a5ee34d6/attachment-0001.html>
>
> ------------------------------
>
> Message: 4
> Date: Mon, 19 Mar 2012 17:11:57 -0700
> From: Jeroen Ooms <jeroen.ooms at stat.ucla.edu>
> To: varnish-misc at varnish-cache.org
> Subject: using the max-age request header
> Message-ID:
> <CABFfbXtVc3vMVB-7_vEUZW6fXup5zte6rVhwL7avsQdqHX1ZHQ at mail.gmail.com>
> Content-Type: text/plain; charset=ISO-8859-1
>
> How do I configure my VLC to let Varnish respect the 'Cache-Control
> max-age' request header? Someone on SO suggested the following:
>
> if (req.http.Cache-Control ~ '\bmax-age=\b`) {
> ???if (std.duration(regsub(req.http.Cache-Control,
> ".*\bmax-age=(\d+)\b.*", "\1s"), 0s) < obj.age) {
> ???????return (pass);
> ???}
> }
>
> However, what I don't like about this is that vcl_pass does not
> actually update the cache with the new entry. How can I configure it
> so that when max age < obj.age, a fresh copy will be fetched and
> inserted into cache?
>
>
>
> ------------------------------
>
> Message: 5
> Date: Tue, 20 Mar 2012 07:25:05 +0100
> From: Per Buer <perbu at varnish-software.com>
> To: Hugues Alary <hugues.alary at gmail.com>
> Cc: varnish-misc at varnish-cache.org
> Subject: Re: Communication between Varnish and the Backend
> Message-ID:
> <CAOXZevDAcWRxDFbUA_mSh4_Hh2S1ukF9PGbmN6X2UThC-Md+5Q at mail.gmail.com>
> Content-Type: text/plain; charset="iso-8859-1"
>
> On Fri, Mar 16, 2012 at 11:42 PM, Hugues Alary <hugues.alary at gmail.com>wrote:
> (..)
>
>
>
> ??- I was wondering if communicating with varnish via HTTP header is a
> ??good solution?
>
> Yes.
>
>
>
> ??- How bad can it be performance wise?
>
> Negligible.
>
>
>
>
> ??- Should I be worried about security (interception/modification of the
> ??communication between Varnish and the backend), even if no credential will
> ??never be sent through HTTP headers? (Also, currently Varnish and the
> ??backend are on the same machine, but chances are that they will in the
> ??future not live on the same host).
>
>
> It's more or less impossible to turn Varnish into an open proxy so I
> wouldn't worry about that.
>
>
>
>
>
> In the future, I plan on instructing varnish not to cache certain pages
> containing user defined query strings. I want the user to be able to
> specify these un-cachable urls query strings directly in the application.
> The application will then send the un-cachable query strings in a header
> X-Application-QueryStringNoCache: "querystring1,querystring2,...".
>
> Is that a bad idea?
>
>
> No. If it works for you then go for it.
>
>
> --
> Per Buer, CEO
> Phone: +47 21 98 92 61 / Mobile: +47 958 39 117 / Skype: per.buer
> *Varnish makes websites fly!*
> Whitepapers <http://www.varnish-software.com/whitepapers> |
> Video<http://www.youtube.com/watch?v=x7t2Sp174eI> |
> Twitter <https://twitter.com/varnishsoftware>
> -------------- next part --------------
> An HTML attachment was scrubbed...
> URL: <https://www.varnish-cache.org/lists/pipermail/varnish-misc/attachments/20120320/59e9f0ef/attachment-0001.html>
>
> ------------------------------
>
> Message: 6
> Date: Tue, 20 Mar 2012 09:24:02 +0000
> From: Michael Borejdo <mib at electronic-minds.de>
> To: "varnish-misc at varnish-cache.org" <varnish-misc at varnish-cache.org>
> Subject: Stale-While-Revalidate or Similar
> Message-ID:
> <BE4EDDBE2C55604EB9F3EBA421CB227A23971439 at EM-MBX-1.electronic-minds.local>
>
> Content-Type: text/plain; charset="us-ascii"
>
> Hello List,
>
> Is there support for something like "stale-while-revalidate" coming to Varnish?
> I need to make the request to my backend-servers async and serve slightly stale content (defined by grace) and I do not want a user to wait for the backend at any time.
> Or is there any other way with using vcl trickery to accomplish this?
> (Unfortunately I cannot seem to find any info on this topic and the thread I found on the list has not been answered) ?[1]
>
> [1] https://www.varnish-cache.org/lists/pipermail/varnish-misc/2012-February/021644.html
>
> Thanks
>
> Michael
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