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Overview

The Flux Notification Controller bridges external event sources (e.g., GitHub, S3 buckets, Helm repositories, Docker registries) with notification targets (Slack, Teams, Discord, Telegram). It comprises:
  • Receiver: Watches changes in external sources and informs Flux controllers.
  • Provider: Encodes and delivers events to external systems based on defined channels and formats.
Events emitted by Flux controllers (Source, Kustomize, Helm, Image) are matched against Alert rules and dispatched via Providers.
The image is a diagram illustrating a notification controller system, showing the flow of source changes and events through various controllers to receivers and providers, with icons representing different platforms and services.

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Configuring Slack Notifications

In this example, we’ll use Slack’s legacy incoming webhook API to post Flux events to a channel.

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1. Create the Slack Webhook Secret

Store your webhook URL in the flux-system namespace: 
kubectl -n flux-system create secret generic slack-webhook \
  --from-literal=address=https://hooks.slack.com/services/SLACK/WEBHOOK/URL
Ensure your Slack workspace has incoming webhooks enabled on the target channel. You can configure and rotate webhooks via Slack App Management.

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2. Define an AlertProvider

Create an AlertProvider named slack-example of type slack, pointing at the general channel and referencing the slack-webhook secret: 
flux create alert-provider slack-example \
  --type slack \
  --channel general \
  --username flux-webhook \
  --secret-ref slack-webhook

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3. Create an Alert

Define an Alert resource to filter and route events of info severity from all Flux controllers in flux-system: 
flux create alert slack-notification \
  --event-severity info \
  --provider-ref slack-example \
  --event-source GitRepository/* \
  --event-source HelmRepository/* \
  --event-source Kustomization/* \
  --event-source Bucket/* \
  --event-source OCIRepository/* \
  --event-source HelmChart/* \
  --event-source HelmRelease/* \
  --event-source ImageRepository/* \
  --event-source ImagePolicy/* \
  --event-source ImageUpdateAutomation/*
Slack’s legacy incoming webhooks may be deprecated in favor of the newer Slack Apps & Block Kit APIs; plan to migrate when possible.

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Flux Notification Resources at a Glance

Resource TypePurposeExample Command
AlertProviderDefines channel, format, and secretsflux create alert-provider slack-example ...
AlertFilters events by severity/sourceflux create alert slack-notification ...
SecretStores webhook URLs or API tokenskubectl create secret generic slack-webhook ...

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References

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