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Notifications and Alerts

Table of Contents​

  1. Concept
  2. Providers
  3. Alerts
  4. Receivers (Webhooks)
  5. Hands-on exercises

1 - Concept​

Notification Controller​

The Notification Controller manages:

  • Alerts: Send notifications on events
  • Receivers: Receive external webhooks

Available CRDs​

CRDDescription
ProviderNotification destination
AlertNotification rules
ReceiverEndpoint for inbound webhooks

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2 - Providers​

Slack​

apiVersion: notification.toolkit.fluxcd.io/v1beta3
kind: Provider
metadata:
  name: slack
  namespace: flux-system
spec:
  type: slack
  channel: deployments
  secretRef:
    name: slack-webhook
---
apiVersion: v1
kind: Secret
metadata:
  name: slack-webhook
  namespace: flux-system
stringData:
  address: https://hooks.slack.com/services/xxx/yyy/zzz

Microsoft Teams​

apiVersion: notification.toolkit.fluxcd.io/v1beta3
kind: Provider
metadata:
  name: teams
  namespace: flux-system
spec:
  type: msteams
  secretRef:
    name: teams-webhook
---
apiVersion: v1
kind: Secret
metadata:
  name: teams-webhook
  namespace: flux-system
stringData:
  address: https://outlook.office.com/webhook/xxx

Discord​

apiVersion: notification.toolkit.fluxcd.io/v1beta3
kind: Provider
metadata:
  name: discord
  namespace: flux-system
spec:
  type: discord
  secretRef:
    name: discord-webhook

GitHub (commit status)​

apiVersion: notification.toolkit.fluxcd.io/v1beta3
kind: Provider
metadata:
  name: github-status
  namespace: flux-system
spec:
  type: github
  address: https://github.com/my-org/my-repo
  secretRef:
    name: github-token
---
apiVersion: v1
kind: Secret
metadata:
  name: github-token
  namespace: flux-system
stringData:
  token: ghp_xxxxxxxxxxxx

All supported providers​

ProviderTypeDescription
SlackslackSlack messages
TeamsmsteamsTeams messages
DiscorddiscordDiscord messages
GitHubgithubCommit status
GitLabgitlabCommit status
BitbucketbitbucketCommit status
GenericgenericHTTP webhook
PagerDutypagerdutyIncidents
OpsgenieopsgenieAlerts

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3 - Alerts​

Basic Alert​

apiVersion: notification.toolkit.fluxcd.io/v1beta3
kind: Alert
metadata:
  name: on-call
  namespace: flux-system
spec:
  providerRef:
    name: slack
  eventSeverity: error
  eventSources:
    - kind: Kustomization
      name: '*'
    - kind: HelmRelease
      name: '*'

Filter by namespace​

spec:
  eventSources:
    - kind: Kustomization
      name: '*'
      namespace: production

Filter by severity​

spec:
  eventSeverity: info  # info, error

Alert with exclusions​

spec:
  eventSources:
    - kind: Kustomization
      name: '*'
  exclusionList:
    - ".*test.*"
    - ".*dev.*"

Complete example​

# Slack pour les erreurs production
apiVersion: notification.toolkit.fluxcd.io/v1beta3
kind: Alert
metadata:
  name: production-errors
  namespace: flux-system
spec:
  summary: "Production deployment alert"
  providerRef:
    name: slack-production
  eventSeverity: error
  eventSources:
    - kind: Kustomization
      name: '*'
      namespace: production
    - kind: HelmRelease
      name: '*'
      namespace: production
---
# Slack pour tous les déploiements (info)
apiVersion: notification.toolkit.fluxcd.io/v1beta3
kind: Alert
metadata:
  name: all-deployments
  namespace: flux-system
spec:
  summary: "Deployment notification"
  providerRef:
    name: slack-deployments
  eventSeverity: info
  eventSources:
    - kind: Kustomization
      name: '*'
    - kind: HelmRelease
      name: '*'

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4 - Receivers (Webhooks)​

Concept​

Receivers make it possible to trigger a Flux reconciliation from the outside.

Create a Receiver​

apiVersion: notification.toolkit.fluxcd.io/v1
kind: Receiver
metadata:
  name: github-webhook
  namespace: flux-system
spec:
  type: github
  events:
    - ping
    - push
  secretRef:
    name: webhook-token
  resources:
    - kind: GitRepository
      name: my-repo

Secret for the token​

apiVersion: v1
kind: Secret
metadata:
  name: webhook-token
  namespace: flux-system
stringData:
  token: <random-token>

Retrieve the webhook URL​

# L'URL est générée automatiquement
kubectl get receiver github-webhook -n flux-system

# Format: /hook/<sha256-hash>

Configure in GitHub​

  1. Go to Settings > Webhooks
  2. URL: https://flux.example.com/hook/<hash>
  3. Content-type: application/json
  4. Secret: the same token as in the Secret

Receiver types​

TypeSource
githubGitHub webhooks
gitlabGitLab webhooks
bitbucketBitbucket webhooks
genericGeneric HTTP POST

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5 - Hands-on exercises​

Exercise 1: Slack alerts​

# slack-notifications.yaml
apiVersion: notification.toolkit.fluxcd.io/v1beta3
kind: Provider
metadata:
  name: slack
  namespace: flux-system
spec:
  type: slack
  channel: flux-alerts
  secretRef:
    name: slack-webhook
---
apiVersion: v1
kind: Secret
metadata:
  name: slack-webhook
  namespace: flux-system
stringData:
  address: "YOUR_SLACK_WEBHOOK_URL"
---
apiVersion: notification.toolkit.fluxcd.io/v1beta3
kind: Alert
metadata:
  name: all-events
  namespace: flux-system
spec:
  providerRef:
    name: slack
  eventSeverity: info
  eventSources:
    - kind: GitRepository
      name: '*'
    - kind: Kustomization
      name: '*'

Exercise 2: GitHub commit status​

# github-status.yaml
apiVersion: notification.toolkit.fluxcd.io/v1beta3
kind: Provider
metadata:
  name: github
  namespace: flux-system
spec:
  type: github
  address: https://github.com/MY-ORG/MY-REPO
  secretRef:
    name: github-token
---
apiVersion: notification.toolkit.fluxcd.io/v1beta3
kind: Alert
metadata:
  name: github-status
  namespace: flux-system
spec:
  providerRef:
    name: github
  eventSeverity: info
  eventSources:
    - kind: Kustomization
      name: my-app

Quiz​

Q1. What is the difference between Alert and Receiver?

Answer
  • Alert: Sends outbound notifications (Flux → Slack/Teams)
  • Receiver: Receives inbound webhooks (GitHub → Flux)

Alert = notify, Receiver = trigger.

Q2. How do you filter alerts to only get errors?

Answer
spec:
  eventSeverity: error

The possible values are info (everything) and error (errors only).

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Key takeaways​

  • Provider: destination (Slack, Teams, GitHub...)
  • Alert: outbound notification rules
  • Receiver: inbound webhooks to trigger
  • Filter by severity and namespace
  • Webhooks for instant sync (no polling wait)

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