- `credential_type` `(string: "password")` – Specifies the type of credential that
  will be generated for the role. Options include: `password`, `rsa_private_key`.
  See the plugin's API page for credential types supported by individual databases.

- `credential_config` `(map<string|string>: <optional>)` – Specifies the configuration
  for the given `credential_type`.

  The following options are available for each `credential_type` value:

  - `password`
    - `password_policy` `(string: <optional>)` - The [policy](/vault/docs/concepts/password-policies)
      used for password generation. If not provided, defaults to the password policy of the
      database [configuration](/vault/api-docs/secret/databases#password_policy).

  - `rsa_private_key`
    - `key_bits` `(int: 2048)` - The bit size of the RSA key to generate. Options include:
      `2048`, `3072`, `4096`.
    - `format` `(string: "pkcs8")` - The output format of the generated private key
      credential. The private key will be returned from the API in PEM encoding. Options
      include: `pkcs8`.
