ODF noobaa certificate - thanos fails with tls: failed to verify certificate: x509: certificate signed by unknown authority

Issue

• Thanos fails to connect to noobaa bucket, configured like this:

apiVersion: v1
kind: Secret
metadata:
  name: thanos-object-storage
  namespace: open-cluster-management-observability
type: Opaque
stringData:
  thanos.yaml: |
    type: s3
    config:
      bucket: openshift-storage-thanos-123456
      endpoint: s3.openshift-storage.svc:443
      insecure: false
      access_key: xxxaaabbb
      secret_key: cccdddeee
      http_config:
        tls_config:
          insecure_skip_verify: true

• On thanos-store pod we can see:

2025-04-03T05:47:59.999967251Z caller=grpc.go:164 level=info service=gRPC/server component=store msg="internal server is shutdown gracefully" err="bucket store initial sync: sync block: BaseFetcher: iter bucket: Get \"https://s3.openshift-storage.svc/openshift-storage-thanos-123456/?location=\": tls: failed to verify certificate: x509: certificate signed by unknown authority"

2025-04-03T05:48:00.000129269Z caller=main.go:161 level=error err="Get \"https://s3.openshift-storage.svc/openshift-storage-thanos-123456/?location=\": tls: failed to verify certificate: x509: certificate signed by unknown authority\nBaseFetcher: iter bucket\ngithub.com/thanos-io/thanos/pkg/block....