Which document will enforce uptime and availability requirements between the cloud customer and cloud provider?

While an SLA is a type of contract, 'Contract' is too broad; the specific term for service performance guarantees is SLA.

An Operational Level Agreement (OLA) is an internal agreement between departments within an organization, supporting an SLA, but it is not directly between the customer and provider.

A Service Level Agreement (SLA) is a contractual agreement between a service provider and a customer that specifies, among other things, the level of service expected from the provider, including uptime guarantees, availability metrics, and performance targets. SLAs often include penalties or remedies for non-compliance, making them critical for enforcing service quality.

A regulation is a rule or law enforced by a government or authoritative body, not a specific document for service performance guarantees between two parties.