[squid-users] Howto make Squid config dependent on hostname?

[Alex Rousskov]

On 9/16/22 06:30, Hildegard Meier wrote:
>> Squid currently only supports three kinds of conditions: true,
>> false, and integer equality comparison (as documented).


> I think it would be very good to give some concrete examples of how
> one can use the if-condition.

I agree.


>> For now, your best option is probably to post-process the versioned
>> configuration to substitute your own custom macro(s). For example, your
>> Squid startup (or deployment) stript can substitute a
>> ${mynamespace:PeerName} macro in squid.conf.template with either true or
>> false, depending on the node, producing squid.conf that Squid can use:
>>
>> cache_peer ${mynamespace:PeerName} sibling 3128 3130
>>
>>
>> If you need to hard-code peer names or substantially different
>> configurations for individual cache peers, then you can do something
>> like this in the template configuration file:
>>
>> if ${mynamespace:AtNode1()}
>>       cache_peer node2.example.com sibling 3128 3130
>> endif
>>
>> if ${mynamespace:AtNode2()}
>>       cache_peer node1.example.com sibling 3128 3130
>> endif

> Sorry, I do not understand what you write.

It is difficult for me to improve the above without knowing which parts 
are unclear to you, but I will try: The above snippets are concrete 
examples of how one can use conditional statements (with custom macros) 
in a squid.conf template. Your custom program will take a 
squid.conf.template containing one of the above snippet and substitute 
the above ${...} custom macros with appropriate values.

On node1, the first template snippet will be replaced with

   cache_peer node2.example.com sibling 3128 3130

On node2, the first template snippet will be replaced with

   cache_peer node1.example.com sibling 3128 3130


On node1, the second template snippet will be replaced with

   if true
        cache_peer node2.example.com sibling 3128 3130
   endif

   if false
        cache_peer node1.example.com sibling 3128 3130
   endif


HTH,

Alex.