devth/k8s-labeler

#!/usr/bin/env bash

set -euo pipefail

# Validate env vars {{{

KUBE_TOKEN=$(cat /var/run/secrets/kubernetes.io/serviceaccount/token)
if [ -z "$KUBE_TOKEN" ]; then
  echo "Error: KUBE_TOKEN is empty"
  exit 1
fi

if [ -z "$KUBE_NAMESPACE" ]; then
  echo "Error: KUBE_NAMESPACE is empty"
  exit 1
fi

HOSTNAME=$(hostname)

# }}}

# Parse labels from ENV and build up a json patch {{{

unset IFS

echo > patch.json
echo "[" >> patch.json
for var in $(compgen -e | grep KUBE_LABEL_); do
  echo "$var = ${!var}"
  label_name="${var//KUBE_LABEL_/}"
  {
    echo '{';
    echo '  "op":"add", "path":"/metadata/labels/'"$label_name"'", "value":"'"${!var}"'"'
    echo '},'
  } >> patch.json
done
sed -i '$ s/.$//' patch.json
echo "]" >> patch.json
cat patch.json

# }}}

# Apply {{{

api_url="https://$KUBERNETES_SERVICE_HOST:$KUBERNETES_PORT_443_TCP_PORT/api/v1/namespaces/$KUBE_NAMESPACE/pods/$HOSTNAME"

echo "Applying JSON patch:"
cat patch.json
echo "at $api_url"

curl -sSk --request PATCH --data "$(cat patch.json)" \
  -H "Authorization: Bearer $KUBE_TOKEN" \
  -H "Content-Type:application/json-patch+json" \
  "$api_url"

# }}}