In cloud computing, the fundamental problem is that multiple organizations are now managing the identity and access management to resources, which can greatly complicate the process. For example, imagine having to provision the same user on dozens-or hundreds-of different cloud services.
Federation is the primary tool used to manage this problem, by building trust relationships between organizations and enforcing them through standards-based technologies.
Reference: CSA Security GuidelinesV.4(reproduced here for the educational purpose)

Malicious actors may leverage cloud computing resources to target users, Organizations or other cloud providers. Examples of misuse of cloud service-based resources include launching DDoS attacks, email spam and phishing campaigns; "mining" for digital currency; large-scale automated click fraud; brute- force compute attacks of stolen credential databases; and hosting of malicious or pirated content.

Application Programming Interfaces allow for programmatic management of the cloud. They are the glue that holds the cloud's components together and enables their orchestration. Since not everyone wants to write programs to manage their cloud, web consoles provide visual interfaces. ln many cases web consoles merely use the same APIs you can access directly.
Reference: CSA Security Guidelines V.4 (reproduced here for the educational purpose)

Ephemeral storage: This type of storage is relevant for SaaS instances and exists only as long as its instance is up. It is typically used for swap files and other temporary storage needs and is terminated with its instance.