type CertificateAuthority interface {
	// Sign generates a certificate for a workload or CA, from the given CSR and cert opts.
	Sign(csrPEM []byte, opts ca.CertOpts) ([]byte, error)
	// SignWithCertChain is similar to Sign but returns the leaf cert and the entire cert chain.
	SignWithCertChain(csrPEM []byte, opts ca.CertOpts) ([]string, error)
	// GetCAKeyCertBundle returns the KeyCertBundle used by CA.
	GetCAKeyCertBundle() *util.KeyCertBundle
}