alertmanager/cluster/testdata/tls_config_with_missing_client.yml

tls_server_config:
  cert_file: "certs/node2.pem"
  key_file: "certs/node2-key.pem"
  client_ca_file: "certs/ca.pem"
  client_auth_type: "VerifyClientCertIfGiven"