DEMO Alerts amp Providers

In this tutorial, you'll configure the Flux Notification Controller to automatically send GitOps alerts to a Slack channel. By the end, you will have a working Slack App, Flux provider, and alert definitions driving real-time notifications.

1. Prepare Your Slack Workspace and Channel

If you don’t have a Slack workspace yet, create one by following Slack’s Help Center instructions:

Once your workspace is ready, create a new channel (public or private) for Flux alerts. In this demo, we’ll use flux-alerts-channel:

If you need to customize the channel settings, use the channel-creation pop-up:

2. Create and Configure a Slack App

2.1 Create the Slack App

1. Go to the Slack API dashboard.
2. Click Create an App, give it a name (e.g., Flux Alerts Application), and select your workspace.

2.2 Configure OAuth & Permissions

Under Features → OAuth & Permissions, add the following Bot Token Scopes:

After adding the scopes, install the app:

On the authorization screen, click Allow:

Once installed, copy the Bot User OAuth Token from the OAuth & Permissions page.

2.3 Invite the Bot to Your Alert Channel

If your alerts channel is private, you must add the app as a member:

Once invited, you’ll see a confirmation in the channel:

3. Configure Flux Notification Controller

3.1 Create the Slack Bot Token Secret

Store your Slack Bot Token in the flux-system namespace:

kubectl -n flux-system create secret generic slack-bot-token \
  --from-literal=token=xoxb-xxxxxxxxxxxxxxxxxxxx

3.2 Define the Slack Provider

Flux’s Provider API lets you specify how notifications are sent. See Flux Notification Providers:

Option A: Apply a YAML manifest
Create notification-provider-slack.yaml:

apiVersion: notification.toolkit.fluxcd.io/v1beta2
kind: Provider
metadata:
  name: notification-provider-slack
  namespace: flux-system
spec:
  type: slack
  channel: flux-alerts-channel
  address: https://slack.com/api/chat.postMessage
  secretRef:
    name: slack-bot-token
  username: flux-bot

Apply it:

kubectl -n flux-system apply -f notification-provider-slack.yaml

Option B: Generate with the Flux CLI

flux create provider notification slack notification-provider-slack \
  --channel flux-alerts-channel \
  --username flux-bot \
  --secret-ref slack-bot-token \
  --address https://slack.com/api/chat.postMessage \
  --export > notification-provider-slack.yaml

3.3 Define an Alert

Alerts let you filter events by severity and resource type before sending them via your provider.

Create notification-alert-slack.yaml:

apiVersion: notification.toolkit.fluxcd.io/v1beta2
kind: Alert
metadata:
  name: notification-alert-slack
  namespace: flux-system
spec:
  eventSeverity: info
  eventSources:
    - kind: Kustomization; name: "*"
    - kind: GitRepository; name: "*"
    - kind: Bucket; name: "*"
    - kind: OCIRepository; name: "*"
    - kind: HelmChart; name: "*"
    - kind: HelmRepository; name: "*"
    - kind: HelmRelease; name: "*"
    - kind: ImageRepository; name: "*"
    - kind: ImagePolicy; name: "*"
    - kind: ImageUpdateAutomation; name: "*"
  providerRef:
    name: notification-provider-slack

Or generate with the Flux CLI:

flux create alert notification-alert-slack \
  --event-severity info \
  --provider-ref notification-provider-slack \
  --event-source Kustomization/* \
  --event-source GitRepository/* \
  --event-source Bucket/* \
  --event-source OCIRepository/* \
  --event-source HelmChart/* \
  --event-source HelmRepository/* \
  --event-source HelmRelease/* \
  --event-source ImageRepository/* \
  --event-source ImagePolicy/* \
  --event-source ImageUpdateAutomation/* \
  --export > notification-alert-slack.yaml

Apply your Alert:

kubectl -n flux-system apply -f notification-alert-slack.yaml

4. Confirm Setup

Make sure Flux picks up your changes and that both the provider and alert are READY:

flux reconcile source git flux-system
flux get alert
flux get providers notification

5. Trigger and Observe Notifications

Change something in your Git repository—for example, reduce the replica count in your deployment:

# in bb-app-source/2-demo/deployment.yaml
spec:
  replicas: 1

Commit and push the update. Once Flux reconciles, you will see a notification in flux-alerts-channel:

6. Verify the Update in Kubernetes

Confirm that your deployment reflects the new replica count:

kubectl -n 2-demo get pods

Congratulations! You have successfully configured Flux Notification Controller to deliver Slack alerts for all your Flux events.

Links and References

• Flux Notification Providers
• Flux CLI
• Kubernetes kubectl Reference
• Slack API Documentation