Event Grid Reactive Webhook Router

Overview

The FlowLibs - Event Grid Reactive Webhook Router turns a Power Automate cloud flow into a first-class Azure Event Grid event handler. Event Grid delivers events over an HTTP webhook, and this flow's built-in When a HTTP request is received trigger is that webhook endpoint. The flow handles the one-time Event Grid subscription-validation handshake (echoing the validationCode so Event Grid accepts the endpoint), then routes each delivered event by its eventType to a tailored Microsoft Teams notification, writes an audit record to Dataverse, and optionally forwards the raw event to a downstream webhook.

Why it matters: Event Grid is the backbone of reactive Azure architectures (blob created, resource deployed, custom topic published). Wiring it to Power Automate lets business workflows react to infrastructure events in near real time — without polling — from a single declarative routing point.

Status: Built — ships Off (demo). Going live requires only authorizing the Teams + Dataverse connections, setting the environment-variable values, and registering the trigger URL as an Event Grid subscription endpoint. Flow Checker: 0 errors / 0 warnings.

Use Case

A platform team wants near-real-time Teams notifications (and downstream automation) whenever specific Azure events fire — a blob lands, a resource group changes, or a custom app publishes a domain event — with one declarative routing point they can extend per event type, plus a durable audit trail in Dataverse.

Flow Architecture

Environment Variables

Connectors & Connections

Connector	API name	Actions used
HHTTP	http	When a HTTP request is received Response Terminate HTTP
Microsoft Teams	shared_teams	PostMessageToConversation
Microsoft Dataverse	shared_commondataserviceforapps	CreateRecord

Note — All connections are referenced as solution connection references; the flow is portable between environments as long as a connection is mapped at import time.

Customization Guide

Almost every realistic variant of this flow can be implemented by changing environment variable values. A few cases require small edits inside the flow definition — those are called out explicitly below.

Add event types

Add a Switch case per new eventType (e.g. Microsoft.Resources.ResourceActionSuccess, a custom-topic event) with its own message + category.

CloudEvents schema

If the topic uses CloudEvents v1.0 instead of the Event Grid schema, validation is a GET handshake with a WebHook-Request-Origin header; branch on triggerOutputs()?['headers'] rather than the body validationCode.

Downstream fan-out

Set flowlibs_DownstreamWebhookUrl to forward routed events; extend the forward branch to target per-category endpoints.

Security

Validate a shared-secret query-string parameter on the trigger URL (compare against an env-var secret) before processing.

Reporting

Build a Power BI report or model-driven view over the flowlibs_eventgridevent table for event-volume and routing analytics.

Key Expressions

The flow is intentionally light on Power Fx / WDL gymnastics — the heaviest expressions are the branch-name concatenation and the approval outcome check. They are listed below in the order they appear in the flow.

@equals(coalesce(triggerBody()?[0]?['eventType'],''),'Microsoft.EventGrid.SubscriptionValidationEvent')

@triggerBody()?[0]?['data']?['validationCode']

@items('For_Each_Event')?['eventType']

item: @outputs('Compose_Event_Log_Row')  // avoids new-table schema-cache lag

@length(triggerBody())

Customize & download