spire/doc/plugin_agent_keymanager_disk.md

Agent plugin: KeyManager "disk"

The disk plugin generates a key pair for the agent's identity, storing the private key on disk. If the agent is restarted, the key will be loaded from disk. If the agent is unavailable for long enough for its certificate to expire, attestation will need to be re-performed.

Configuration	Description
directory	The directory in which to store the private key.

A sample configuration:

    KeyManager "disk" {
        plugin_data = {
            directory = "/opt/spire/data/agent"
        }
    }