[squid-users] Switch cache peer Parent server for every 30 minutes

[Antony Stone]

On Wednesday 10 June 2020 at 18:11:03, Prem Chand wrote:

> Hi Alex,
> 
> Thanks for responding to my issue  . I didn't get how the math was done(why
> it's multiplied by 2) to get 16 slots if possible could you please elaborate
> with an example.

I believe what Alex meant was:

You want 30 minute timeslots for each of 3 peers, which is 48 half-hour 
timeslots throughout the day.

However, you only need to define 48/3 of these for peer A, and 48/3 of them for 
peer B, and then let peer C deal with anything not already handled (so it 
doesn't need its own definitions).

48/3 = 16, therefore you define 16 half-hour periods when you want peer A to do 
the work, 16 half-hour periods for peer B, and then just say "peer C, handle 
anything left over".


Regards,


Antony.

> On Wed, Jun 10, 2020 at 7:12 PM Alex Rousskov wrote:
> > On 6/10/20 6:09 AM, Prem Chand wrote:
> > > My squid cache peer has 3 parent IP’s configured. I need to send HTTPS
> > > requests to the first parent IP for 30 minutes and after to the 2nd
> > > parent IP for 30 minutes and then to 3rd IP for 30 minutes and this
> > > switching needs to happen continuously .Could you please let us know
> > > how I can achieve this?
> > 
> > If you are OK with hard-coded usage time slots for each peer, then I
> > would use two[1] "time" ACLs and cache_peer_access rules. Look for
> > "aclname time" in squid.conf.documented. You will have to generate a
> > list of (24*2/3=16) staggered time slots for each of the two ACLs, but
> > it should work. This may be the simplest solution.
> > 
> > [1] You need two ACLs for three peers because the third peer should get
> > the requests that the first two peers were not allowed to get.
> > 
> > ----
> > 
> > With a modern Squid, you could also implement this using a more flexible
> > (and more expensive, on several layers!) architecture with two ACLs:
> > 
> > 1. An external ACL that returns the right cache peer name to use via a
> > keyword=value annotation API. This always-matching ACL should be
> > attached to http_access or a similar directive that supports slow ACLs.
> > Its goal is to annotate the request. You will need to write a
> > script/program that will compute the right annotations based on time or
> > some other factors. This is where the flexibility of this solution is
> > coming from.
> > 
> > 2. A "note" ACL attached to cache_peer_access directives, allowing
> > access to peer X if the external ACL in item 1 returned
> > use_cache_peer_=X. The "note" ACL is a fast ACL and, hence, can be
> > reliably used with cache_peer_access.
> > 
> > If you already have another external ACL, you may be able to piggyback
> > annotations in item 1 to whatever that ACL is already doing.
> > 
> > For more information, search for "keyword=value" and "acl aclname note"
> > in your squid.conf.documented and see
> > https://wiki.squid-cache.org/Features/AddonHelpers#Access_Control_.28ACL.
> > 29
> > 
> > 
> > HTH,
> > 
> > Alex.

-- 
Neurotics build castles in the sky;
Psychotics live in them;
Psychiatrists collect the rent.


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