I am trying to follow these steps to provide a different credential file for gcp.
https://github.com/vmware-tanzu/velero/issues/3430

I was trying to use the key credentialsFile and provide the file as an input but since the controller runs inside the velero pod, wont this look for the file inside the pod? 

https://github.com/vmware-tanzu/velero-plugin-for-gcp/pull/52/files#diff-bc262f262dbdc4faf49f17fca5c228c9b4121cb64cc2f327e0d82bd562703bc1R96

Possible resolution:

Add mount support here: https://github.com/openshift/oadp-operator/blob/master/pkg/credentials/credentials.go#L41

and if the credentialsFile key is present, we might need to mount another file, then GCPCredentialsEnvKey would be consumed by the VSL and credentialsFile key would be consumed by BSL