#!/bin/bash

if [[ $1 == "--config" ]]; then
  cat <<EOF
{
  "onKubernetesEvent": [
    {
      "kind": "Ingress",
      "event": ["add"]
    }
  ]
}
EOF
else
  json=${BINDING_CONTEXT_PATH}
  ns=$(jq -r '.[0].resourceNamespace' ${json})
  res=$(jq -r '.[0].resourceName' ${json})
  tmp=$(mktemp)
  kubectl -n "${ns}" get ingress "${res}" -ojson >${tmp} || { echo "error: getting ingress ${ns}/${res} failed">&2; exit 0; }
  class=$(jq -r '.metadata.annotations."kubernetes.io/ingress.class"' ${tmp})
  [[ "${class}" == "nginx" ]] || { echo "notice: ingress class ${ns}/${res} is not 'nginx'"; exit 0; }
  port=$(jq -r '.spec.rules[0].http.paths[0].backend.servicePort' ${tmp})
  ann=$(jq -r '.metadata.annotations."nginx.ingress.kubernetes.io/configuration-snippet"' ${tmp})
  rm -f ${tmp}
  [[ "${ann}" =~ "l5d-dst-override" ]] && { echo "notice: ingress ${ns}/${res} already has 'l5d-dst-override' header"; exit 0; }
  [[ "${ann}" == "null" ]] && ann="" || ann="${ann}"$'\n'
  ann="${ann}proxy_set_header l5d-dst-override \$service_name.\$namespace.svc.cluster.local:${port}"$';\nproxy_hide_header l5d-remote-ip;\nproxy_hide_header l5d-server-id;\n'
  kubectl -n "${ns}" annotate ingress "${res}" nginx.ingress.kubernetes.io/configuration-snippet="${ann}" --overwrite
fi