Yes, vSphere 6.5 introduced REST API and it's called "vSphere Automation API".
But this API don't has full functionality yet. So I'm not sure if you can get the CPU, Memory and Storage information for a cluster object.
More resources:
vSphere Automation API - VMware API Explorer - VMware {code}
Getting Started with the vSphere Automation SDK for REST - VMware {code} - VMware Blogs
GitHub - vmware/vsphere-automation-sdk-rest: REST Samples for the vSphere Automation SDK
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Regards,
Sebastian
VCP6.5-DCV // VCP7-CMA // vSAN 2017 Specialist
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