Cloud Function for GKE upgrade notifications

README.md

We want to receive notifications when a Kubernetes cluster upgrades. For this we can configure PubSub subscriptions:

const exec = require("child_process").execSync;

const mapping = {
  "my-dev-project": [{ name: "clusterA", region: "europe-west4" }, { name: "clusterB", region: "us-east1" }],
  "my-prod-project": [{ name: "clusterC", region: "europe-west4" }, { name: "clusterD", region: "us-east1" }],
};

for (const PROJECT in mapping) {
  exec(`gcloud pubsub topics create k8s-upgrades --project=${PROJECT}`)
  for (const { name: CLUSTERNAME, region: REGION } of mapping[project]) {
    exec(`gcloud container clusters update ${CLUSTERNAME} --notification-config=pubsub=ENABLED,pubsub-topic=projects/${PROJECT}/topics/k8s-upgrades --region=${REGION}`);
  }
}

And a Cloud Function to notify us on Slack:

printf "https://hooks.slack.com/services/T00000000/B00000000/XXXXXXXXXXXXXXXXXXXXXXXX" | gcloud secrets create K8S_UPGRADES_SLACK_WEBHOOK_URL --data-file=-

gcloud functions deploy k8s-upgrades \
  --runtime=nodejs16 \
  --entryPoint=notify \
  --set-secrets 'SLACK_WEBHOOK_URL=K8S_UPGRADES_SLACK_WEBHOOK_URL:1' \
  --trigger-topic=k8s-upgrades

index.js

const https = require('https');
const url = require('url');

// Settings via environment
const slackWebhookURL = process.env.SLACK_WEBHOOK_URL; // e.g. 'https://hooks.slack.com/services/T0000/B0000/XXXXXXXXX';

/**
 * Triggered from a message on a Cloud Pub/Sub topic.
 * Converts event to Slack webhook.
 */
exports.notify = (event, context) => {
  console.log({ event, context });
  const slackRequest = https.request({
    hostname: url.parse(slackWebhookURL).hostname,
    method: 'POST',
    path: url.parse(slackWebhookURL).path,
    headers: { 'Content-Type': 'application/json' },
  });
  slackRequest.write(JSON.stringify(convertEvent(event, context)));
  slackRequest.end();
};

/**
 * Convert the PubSub event to Slack payload
 * @param {!Object} event Event payload. Contains human-readable message in [data] and machine readable data in [attributes]
 * @param {!Object} context Metadata for the event.
 * @returns {Object} Slack message payload
 *
 * @docs https://cloud.google.com/kubernetes-engine/docs/how-to/cluster-upgrade-notifications
 * @docs https://github.com/shipwreckdev/gke-notification-handler/blob/main/main.py
 */
function convertEvent(event, context) {
  const message = Buffer.from(event.data, "base64").toString("utf8");
  const cluster = event["attributes"]["cluster_name"];
  const location = event["attributes"]["cluster_location"];
  const project = event["attributes"]["project"];
  const payload = JSON.parse(event["attributes"]["payload"]);

  // attributes.type_url = "type.googleapis.com/google.container.v1beta1.UpgradeEvent"
  // attributes.type_url = "type.googleapis.com/google.container.v1beta1.UpgradeAvailableEvent"
  const type_url = event["attributes"]["type_url"] || "";
  const title = type_url.indexOf("UpgradeEvent") >= 0 || payload.operation
    ? "UpgradeEvent"
    : "UpgradeAvailableEvent";

  const text = `*${title}:*
${message}
  
*Project:* ${project}
*Cluster:* ${cluster}
*Location:* ${location}
  
${code("javascript", JSON.stringify(event, null, 2))}
`;
  return { mrkdwn: true, text };
}

function code(lang, code) {
  return "```" + lang + "\n" + code + "\n```";
}