Microsoft Azure Application Gateway Unhealthy Backend Host Pool Sentinel

id: azure-app-gateway-unhealthy-backend-sentinel
namespace: company.cloud

inputs:
  - id: subscription_id
    type: STRING
    description: Azure Subscription ID.
  - id: resource_group
    type: STRING
    description: Azure Resource Group name.
  - id: gateway_name
    type: STRING
    description: Azure Application Gateway name.

tasks:
  - id: check_backend_health
    type: io.kestra.plugin.scripts.shell.Commands
    containerImage: mcr.microsoft.com/azure-cli:latest
    commands:
      - |
        az login --service-principal -u "{{ secret('AZURE_CLIENT_ID') }}" -p "{{ secret('AZURE_CLIENT_SECRET') }}" --tenant "{{ secret('AZURE_TENANT_ID') }}" --output none
        az account set --subscription "{{ inputs.subscription_id }}"

        # Query backend health status across all address pools
        az network application-gateway show-backend-health           --name "{{ inputs.gateway_name }}"           --resource-group "{{ inputs.resource_group }}"           --query "backendAddressPools[].backendHttpSettingsCollection[].backendAddresses[?health!='Healthy']"           --output json > /tmp/gateway_telemetry.json

        UNHEALTHY_COUNT=$(jq 'flatten | length' /tmp/gateway_telemetry.json)
        echo "::set-output name=unhealthy_count::$UNHEALTHY_COUNT::"

  - id: evaluate_unhealthy_backends
    type: io.kestra.plugin.core.flow.If
    condition: "{{ outputs.check_backend_health.vars.unhealthy_count | int > 0 }}"
    then:
      - id: notify_networking_team
        type: io.kestra.plugin.slack.notifications.SlackIncomingWebhook
        url: "{{ secret('SLACK_WEBHOOK') }}"
        payload: |
          {
            "channel": "#networking-ops",
            "attachments": [
              {
                "color": "danger",
                "title": "🚨 Azure Application Gateway Unhealthy Backend Alert",
                "text": "Application Gateway `{{ inputs.gateway_name }}` detected *{{ outputs.check_backend_health.vars.unhealthy_count }} unhealthy backend host(s)*! Ingress traffic is experiencing degraded redundancy or service routing failures.",
                "footer": "Kestra Cloud Sentinel • Microsoft Azure Networking"
              }
            ]
          }

errors:
  - id: alert_pipeline_failure
    type: io.kestra.plugin.slack.notifications.SlackIncomingWebhook
    url: "{{ secret('SLACK_WEBHOOK') }}"
    payload: |
      {
        "channel": "#networking-ops",
        "attachments": [
          {
            "color": "danger",
            "title": "⚠️ Azure Application Gateway Sentinel Failure",
            "text": "Failed to query Application Gateway backend health. Verify gateway name and service principal network reader access.",
            "footer": "Kestra Workflow Failure Sentinel"
          }
        ]
      }

triggers:
  - id: periodic_schedule
    type: io.kestra.plugin.core.trigger.Schedule
    cron: "*/15 * * * *"
    disabled: true
    inputs:
      subscription_id: replace-with-your-subscription-id
      resource_group: replace-with-your-resource-group
      gateway_name: replace-with-your-gateway-name