Load balancing apache 2.4 ProxyPass configuration meaning

Luca

9/9/23, 3:05 PM

I'm studying apache 2.4 and I've found this configuration as example. What I don't understand is the definition of ProxyPass, they have defined "balancer://cluster/example1/api" but in the Proxy directive there is only "balancer://cluster".

What they have done in this configuration? Can anyone explain me with some pratice example?

<VirtualHost *:10000> 
    ProxyRequests Off
    ProxyTimeout 300
    ProxyPreserveHost On
    ProxyVia On
    <Proxy balancer://cluster>
        BalancerMember http://localhost:8888         
        ProxySet lbmethod=bytraffic
    </Proxy>    
    ProxyPass /content/sub1 balancer://cluster/example1/api  
</VirtualHost>

0 + 0

configuration

load-balancing

apache-2.4

Martin

9/9/23, 3:20 PM

This directive makes apache act as a [reverse proxy](https://en.wikipedia.org/wiki/Reverse_proxy), which means any request to ```/content/sub1``` or below will not be served with a local html document, but will be passed onto the backend server defined in that ```ProxyPass``` directive.

Luca

9/9/23, 3:36 PM

but it's referring to the balancer as the second argument "balancer://cluster/example1/api ".

Martin

9/9/23, 4:30 PM

well, instead of pointing the reverse proxy to a fixed backend server, you can use it as load balancer: the first incoming request is forwarded to backend server 1, the second request to backend server 2, and so on. This way, each backend server must only be able to handle a part of the overall load. In this case, the balancing algorithm is obviously the number of bytes received by each backend server.

Luca

9/10/23, 8:45 AM

Thank you Martin for you explanation, I really appreciate. But what I don't understand is why in ProxyPass they put "balancer://cluster/example1/api " when in the Proxy directive they have <Proxy balancer://cluster>? How is the apache behaviors?

Luca

9/10/23, 9:08 AM

I mean, what's happen when they put as second parameter of ProyPass "balancer://cluster/example1/api" instead of "balancer://cluster" as define in the <Proxy> directive?

Martin

9/10/23, 10:09 AM

that is the path you are accessing... any URI like ```http://www.example.com/questions/3456/my-document``` are build made of the access scheme (http), the server name (www.example.com), and the path your browser is trying to access ( /questions/3456/my-document ). This is also true for load-balanced servers, as they must know which document to deliver!

Luca

9/10/23, 11:58 AM

Ohhh ok, now I see, I thought that second parameter must match the the url in the proxy directive

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I sit in a Tesla and translated this thread with Ai:

EN: Load balancing apache 2.4 ProxyPass configuration meaning

TH: Load balancing apache 2.4 ความหมายการกำหนดค่า ProxyPass

RO: Echilibrarea sarcinii apache 2.4 Sensul configurației ProxyPass

RU: Значение конфигурации Apache 2.4 ProxyPass для балансировки нагрузки

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