`cert_pool`: add `combined`/`multi` and `system`

[mohammed90]

Issue Details

combined merges multiple roots sources, and system just pulls from x509.SystemCertPool()

Assistance Disclosure

AI not used

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No response

[FreyreCorona]

i like to work on this issue , can you provide more information about ?

[francislavoie]

https://caddyserver.com/docs/caddyfile/directives/tls#trust-pool-providers we have these existing modules for trust pool, we should add two more.

[HarshPatel5940]

I've implemented the system trust pool module which uses x509.SystemCertPool() and works as expected. commit here

However, the combined module has a fundamental limitation: Go's x509.CertPool doesn't expose its certificates, making it impossible to merge multiple pools.

so should we modify the CA interface to add a method like Certificates() []*x509.Certificate so sources can expose their certificates for merging? not sure how to proceed here

[FreyreCorona]

@HarshPatel5940 do you wanna make PR on your implementation ? i been working on this issue but i buzzy this weeks on my primary work .
You already finish it ?

[HarshPatel5940]

@HarshPatel5940 do you wanna make PR on your implementation ? i been working on this issue but i buzzy this weeks on my primary work .
You already finish it ?

I would be happy to help, but it's the first time I plan to contribute here and I already feel doubtful with my current implementation. So I had the question.

Is it possible for you to review my commit before I draft PR? Or simply do it?

[FreyreCorona]

Idk , if you do already test the code and work as expected , create a PR and the members will review it better than me , also i can only see it and give to you some advice , simply do it

[HarshPatel5940]

Idk , if you do already test the code and work as expected , create a PR and the members will review it better than me , also i can only see it and give to you some advice , simply do it

I did add tests and tested. but the original request for combined certs is not satisfied with my PR and the plan i have to complete the requirement seems like a breaking change thats why i asked here

edit: draft pr here