R2 custom SSL certificate


I’ve created R2 bucket and attached CNAME record to it,
but I see that it uses different ssl cert from what is being using for the main domain,
is it possible to attach different SSL cert to R2 bucket?


Welcome to the Community Forum!

Sadly, the answer to that is mostly no.*
R2 Custom Domains get issued a CF for SaaS Certificate. You can find the priority of certificates here: Certificate and hostname priority · Cloudflare SSL/TLS docs
The only way you can use another certificate with an R2 Custom Domain is if it is a custom uploaded certificate (Business required, also kind of a pain to keep renewed), or Keyless SSL (Enterprise).

Otherwise, you could use a Cloudflare Worker bound to your bucket via a Worker Custom Domain (which makes an advanced certificate you can delete under Edge Certificates) or an http route. For example: GitHub - kotx/render: Cloudflare Worker to proxy and cache requests to R2
Only downside is each request costs you a worker invocation and a Class B (if uncached), unlike R2 Custom Domains which just cost you a Class B if uncached.