Seeking Help to Resolve Access Issues with Google Cloud Load Balancer and CDN

[Yash_A]

Hey GCP Community,

I'm feeling a bit stuck and would really appreciate your help. I've set up a Google Cloud Global External Application Load Balancer with a backend bucket and enabled CDN. I also added an SSL certificate to ensure all traffic is securely routed to HTTPS.

However, when I try to access the storage files through the CDN, I keep getting an AccessDenied Error (403). I want to ensure that only the load balancer can access the bucket to fill the CDN cache, but I'm not sure how to set it up correctly.

I found two possible solutions online:

1. Make the Storage Bucket public: I don't want to do this, as I want the bucket's access restricted to just the load balancer.
2. Grant the load balancer's service account access to the bucket: The problem is, I can't find any service account related to the load balancer.

Has anyone encountered a similar issue or can offer guidance? I want to resolve this without making the bucket public or giving access to anyone else. Any advice or steps would be greatly appreciated!

Thank you so much in advance!