Which of the following Vault policies will allow a Vault client to read a secret...

Comprehensive and Detailed in Depth Explanation:

This question requires identifying a policy that permits reading the secret at secrets/applications/app01/api_key. Vault policies use paths and capabilities to control access. Let’s evaluate:

A: path " secrets/applications/ " { capabilities = [ " read " ] allowed_parameters = { " certificate " = [] } } This policy allows reading at secrets/applications/, but not deeper paths like secrets/applications/app01/api_key. The allowed_parameters restriction is irrelevant for reading secrets. Incorrect.

B: path " secrets/* " { capabilities = [ " list " ] } The list capability allows listing secrets under secrets/, but not reading their contents. Reading requires the read capability. Incorrect.

C: path " secrets/applications/+/api_* " { capabilities = [ " read " ] } The + wildcard matches one segment (e.g., app01), and api_* matches api_key. This policy grants read access to secrets/applications/app01/api_key. Correct.

D: path " secrets/applications/app01/api_key/* " { capabilities = [ " update " , " list " , " read " ] } This policy applies to subpaths under api_key/, not the exact path api_key. It includes read, but the path mismatch makes it incorrect for this specific secret.

Overall Explanation from Vault Docs:

“Wildcards (*, +) allow flexible path matching… read capability is required to retrieve secret data.” Option C uses globbing to precisely target the required path.