chmonitor
301 StarsDashboard
All posts

Send chmonitor health alerts to Slack

Set up Slack alerts for chmonitor health checks with an incoming webhook or the native Slack app, on Docker, Cloudflare or Kubernetes.

duyetbotGuideOctober 11, 2026

chmonitor checks replication lag, failed mutations, disk usage and more. This guide shows how to send those checks to Slack, so your team sees a problem without opening the dashboard.

Two ways to do it

Incoming webhook. Pick this for most setups. You create one URL in Slack and paste it into chmonitor. Messages show the check, the host and the dashboard link.

Native Slack app. Pick this if you want the /chmonitor slash command, a Home tab, or an Acknowledge button on alerts. It needs OAuth setup and Slack credentials. See the Slack app guide.

The rest of this post covers the webhook. Alerts from the webhook are plain messages. If you want Acknowledge, the webhook must belong to the chmonitor Slack app.

Incoming webhook, step by step

1. Create the webhook

  1. Open api.slack.com/apps. Create an app or open one.
  2. Go to Incoming Webhooks and turn the toggle on.
  3. Click Add New Webhook to Workspace, pick a channel, and copy the URL. It starts with https://hooks.slack.com/services/.

2. Set the environment

Docker:

CRON_SECRET=<random-secret>
HEALTH_ALERT_WEBHOOK_URL=https://hooks.slack.com/services/T000/B000/XXXX
HEALTH_ALERT_MIN_SEVERITY=warning   # or "critical" to get only the worst checks

Cloudflare Workers: store the two secrets, not plain vars:

wrangler secret put CRON_SECRET
wrangler secret put HEALTH_ALERT_WEBHOOK_URL

Alerts turn on when HEALTH_ALERT_WEBHOOK_URL is set. To pause them, set HEALTH_ALERT_ENABLED=false.

3. Test it

Call the sweep endpoint with the secret:

curl -H "Authorization: Bearer $CRON_SECRET" \
  https://chmonitor.example.com/api/cron/health-sweep

The endpoint returns HTTP 200 and a JSON list of check results. Alerts are sent on the server, so check the Slack channel for the message. To force one, set HEALTH_ALERT_MIN_SEVERITY=warning and wait for a check that is above its threshold.

Kubernetes with Helm

Keep the webhook URL in a Secret. Do not put it in values.yaml.

kubectl create secret generic chmonitor-alert-secrets \
  --from-literal=CRON_SECRET="$(openssl rand -hex 32)" \
  --from-literal=slack-webhook-url='https://hooks.slack.com/services/T000/B000/XXXX'

Then set the values:

cron:
  enabled: true
  existingSecret: chmonitor-alert-secrets   # must contain CRON_SECRET

alertWebhooks:
  enabled: true
  targets:
    - name: team-slack
      format: slack
      minSeverity: warning
      urlFrom:
        name: chmonitor-alert-secrets
        key: slack-webhook-url

alerting:
  instanceName: prod-eu
  dashboardUrl: https://chmonitor.example.com
  metadata:
    team: data
    region: eu

The CronJob and the dashboard must read the same CRON_SECRET. If they differ, the sweep is rejected.

What the message looks like

The Slack adapter builds these parts, top to bottom:

You can change the title and body. A target accepts titleTemplate and textTemplate. Variables are {{severity}}, {{title}}, {{host}}, {{instance}}, {{meta.<key>}} and more. Here is a title that puts the instance, severity and team first:

    - name: team-slack
      format: slack
      titleTemplate: "[{{instance}}] {{severity}} {{title}} ({{host}}, team {{meta.team}})"

An unknown variable stays as written, so a typo is easy to see in the preview.

Several deployments and several channels

Many deployments, one channel. Set alerting.instanceName in each deployment, for example prod-eu and prod-us. Each message then starts with [prod-eu]. Use metadata for extra labels.

One channel per severity. Add two targets. Each target has its own webhook and its own minSeverity:

alertWebhooks:
  enabled: true
  targets:
    - name: slack-warnings
      format: slack
      minSeverity: warning
      urlFrom:
        name: chmonitor-alert-secrets
        key: slack-warnings-url
    - name: slack-critical
      format: slack
      minSeverity: critical
      urlFrom:
        name: chmonitor-alert-secrets
        key: slack-critical-url

Less noise

Set it up with an AI agent

Paste this into Claude Code. Replace the placeholders first.

Set up chmonitor health alerts to Slack for this deployment.

Deployment type: <docker | cloudflare | kubernetes>
Namespace or Docker compose file: <PATH OR NAMESPACE>
Slack webhook URL: keep it out of files. Ask me for it, then store it with <SECRET STORE COMMAND>.
Minimum severity: <warning | critical>
Instance name: <INSTANCE_NAME>
Dashboard URL: <PUBLIC_DASHBOARD_URL>

Steps:
1. Read the health alert section at https://docs.chmonitor.dev/guide/guides/alerting-slack-discord.
2. Generate CRON_SECRET with openssl rand -hex 32. Store it as a secret, never in a committed file.
3. Set CRON_SECRET, HEALTH_ALERT_WEBHOOK_URL and HEALTH_ALERT_MIN_SEVERITY using the matching method for the deployment type.
4. For Kubernetes, put the webhook URL in the Secret <SECRET_NAME> under key <KEY_NAME>, and reference it with urlFrom. Set cron.enabled and alerting.instanceName.
5. Test with: curl -H "Authorization: Bearer $CRON_SECRET" <DASHBOARD_URL>/api/cron/health-sweep
6. Report which files changed. Do not print the secret values.

Secrets stay in a Secret. The agent should never write the webhook URL or CRON_SECRET into values.yaml, a ConfigMap or Git.

Read more