I'm doing something like this for now, but there might be a better way?

awsAuthConfigmap.data.apply(v => {
  // console.log(YAML.parse(v.mapRoles))
  let roleMappings = YAML.parse(v.mapRoles)
  let roleMapping = {
    rolearn: "TEST",
    username: "TEST",
    groups: "TEST",
}
  roleMappings.push(roleMapping)
  console.log(roleMappings)
})