Caching Modified URLs by Varnish instead of the original requested URL

[Uday Kumar]

Hello All,


For our spring boot application, we are using Varnish Caching in a
production environment.




Requirement: [To utilize cache effectively]

Modify the URL (Removal of unnecessary parameters) while caching the user
request, so that the modified URL can be cached by varnish which helps
improve cache HITS for similar URLs.


For Example:

Let's consider the below Request URL

Url at time t, 1. samplehost.com/search/ims?q=bags&source=android
&options.start=0


Our Requirement:

To make varnish consider URLs with options.start=0 and without
options.start parameter
as EQUIVALENT, such that a single cached response(Single Key) can be
utilized in both cases.


*1st URL after modification:*

samplehost.com/search/ims?q=bags&source=android


*Cached URL at Varnish:*

samplehost.com/search/ims?q=bags&source=android



Now, Url at time t+1, 2. samplehost.com/search/ims?q=bags&source=android


At present, varnish considers the above URL as different from 1st URL and
uses a different key while caching the 2nd URL[So, it will be a miss]


*So, URL after Modification:*

samplehost.com/search/ims?q=bags&source=android


Now, 2nd URL will be a HIT at varnish, effectively utilizing the cache.



NOTE:

We aim to execute this URL Modification without implementing the logic directly
within the default.VCL file. Our intention is to maintain a clean and
manageable codebase in the VCL.



To address this requirement effectively, we have explored two potential
Approaches:


Approach-1:



Approach-2:




1. Please go through the approaches mentioned above and let me know the
effective solution.

2. Regarding Approach-2

At Step 2:

May I know if there is any way to access and execute a custom subroutine
from another VCL, for modifying the Request URL? if yes, pls help with
details.

At Step 3:

Tomcat Backend should receive the Original Request URL instead of the
Modified URL.

3. Please let us know if there is any better approach that can be
implemented.



Thanks & Regards
Uday Kumar
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://www.varnish-cache.org/lists/pipermail/varnish-misc/attachments/20230822/1b739578/attachment-0001.html>