When clients interact with the Vault, what kind of request structure do they typically use?

Clients interacting with HashiCorp Vault typically use RESTful requests with JSON payloads. This approach aligns with the modern web standards that emphasize simplicity and consistency in API design.

REST (Representational State Transfer) is an architectural style that defines a set of constraints and characteristics based on stateless communications, and it leverages standard HTTP methods such as GET, POST, PUT, and DELETE. JSON (JavaScript Object Notation) is a lightweight data interchange format that is easy to read and write for humans and machines, making it an ideal choice for exchanging data between clients and servers.

Using JSON as the payload format complements the RESTful nature of the API. This structure allows for a seamless exchange of data where clients can request information or perform actions on the Vault server, such as retrieving secrets, managing access policies, or generating dynamic credentials. The design promotes clear structuring of requests and responses, which enhances compatibility with a broad range of programming languages and platforms.

The other choices do not align with the standard practices in Vault’s design. GraphQL queries introduce complexity that is unnecessary for Vault's operations, XML is less commonly used in modern APIs compared to JSON, and plain text requests lack the structure needed for meaningful data interchange with a secure service like Vault.