Re: [squid-users] Want to monitor squid, by pulling an image which is local.

On Fri, May 27, 2011 at 1:39 AM, Amos Jeffries <squid3_at_treenet.co.nz> wrote:
> On 27/05/11 10:05, Tory M Blue wrote:
>>
>
> Seems to be some confusion.
>
>  Stale vs non-stale content is a matter for the website cache control HTTP
> headers. Squid *will* serve stale content according to RFC 2616.
>
>  Proxy up/down merely determines how much lag the client gets exposed to as
> unavailable peers get contacted for data.
>
> A peer is unavailable if either its box is down OR you manually dropped it
> out. It can't be available while shutdown, for instance.
>
> Now why does the Squid box being up/down matter independently of Squid
> itself?

Say Squid crashes, my icmp host check will succeed and with no other
check in place the squid server continues to be passed end user
requests that it can't hope to fulfill.So end users get errors.
(Remember the F5 accepted the connection and passed it on to a now
defunct server, so there is no real client side retransmission or
other, the user will get a 404 or other error.).

Another scenario I have a monitor check that grabs an image from a
cache_peer through squid, it succeeds squid is up and running, the LB
leaves squid in the VIP. Now we take the cache_peers down, or they
fail, overloaded or something <shrug>, the LB tries to pull a test
image through squid, it fails (cache_peer is not available), the LB
pulls the squid cache(s) out of the VIP as well. I'm now completely
down, vs having sometime for the caches to serve data from it's local
store (I believe with my testing, that if the cache_peer is not
available and Squid has the requested image, it will serve it up,
regardless of age (could be stale, can't revalidate it etc). Am I
mistaken?

>>

> Squid has a set of icons which it loads for FTP directory listings etc.
> They are configured in the /etc/squid/mime.conf configuration file.
>
> If you need a test image loaded by Squid the URL
> http://$host/squid-internal-static/icons/unknown.gif
> should come back from squid-2 with a question-mark icon.

Your a prince, but who is Anthony?

squid-internal-static/icons/anthony-unknown.gif :)

>>
>> monitorurl doesn't quite do it, since I'm looking for a test from a
>> 3rd party device.
>
> monitorurl takes any URL you want *through* the cache_peer link. If it comes
> back okay the peer is assumed to be accessible and ready to accept traffic.
>

Yes, but as you can see I'm trying to verify that the squid process is
working, I have other checks to verify that the cache_peers are up and
running (Again another LB monitor that checks for a status file,
up/down (for maintenance reasons).

But.. So what happens if the monitorurl fails?

-Thanks again sir, I owe you a beer/coffee/soda/some variety of flavored water

Tory
Received on Fri May 27 2011 - 17:02:54 MDT