Event Grid for event routing in Azure - Mini Project: Build & Apply

Event Grid for event routing

📖 Scenario: You are setting up a simple event routing system in Azure using Event Grid. This system will route events from a storage account to a function app that processes these events.

🎯 Goal: Build an Azure Event Grid subscription that routes events from a storage account to an Azure Function endpoint.

📋 What You'll Learn

Create a resource group variable with the exact name resource_group set to myResourceGroup.

Create a storage account variable with the exact name storage_account set to mystorageacct.

Create an Event Grid subscription variable with the exact name event_subscription set to myeventsubscription.

Create an endpoint variable with the exact name endpoint_url set to https://myfunctionapp.azurewebsites.net/runtime/webhooks/eventgrid?functionName=ProcessEvent.

Create an Event Grid subscription resource that connects the storage account to the endpoint.

💡 Why This Matters

🌍 Real World

Event Grid is used to route events from Azure resources to various endpoints for processing, enabling reactive and serverless architectures.

💼 Career

Understanding Event Grid subscription configuration is essential for cloud engineers and developers working with event-driven Azure solutions.

1

DATA SETUP: Define resource group and storage account variables

Create a variable called resource_group and set it to myResourceGroup. Then create a variable called storage_account and set it to mystorageacct.

Azure

# Your code here

Hint

Use simple string variables to hold the resource group and storage account names.

2

CONFIGURATION: Define event subscription and endpoint URL variables

Create a variable called event_subscription and set it to myeventsubscription. Also create a variable called endpoint_url and set it to https://myfunctionapp.azurewebsites.net/runtime/webhooks/eventgrid?functionName=ProcessEvent.

Azure

resource_group = "myResourceGroup"
storage_account = "mystorageacct"
# Your code here

Hint

Use string variables for the event subscription name and the function app endpoint URL.

3

CORE LOGIC: Create the Event Grid subscription resource configuration

Create a dictionary called event_grid_subscription with keys name, scope, and destination. Set name to event_subscription. Set scope to the storage account resource ID string in the format /subscriptions/00000000-0000-0000-0000-000000000000/resourceGroups/{resource_group}/providers/Microsoft.Storage/storageAccounts/{storage_account}. Set destination to a dictionary with key endpointType set to WebHook and key properties set to a dictionary with key endpointUrl set to endpoint_url.

Azure

resource_group = "myResourceGroup"
storage_account = "mystorageacct"
event_subscription = "myeventsubscription"
endpoint_url = "https://myfunctionapp.azurewebsites.net/runtime/webhooks/eventgrid?functionName=ProcessEvent"
# Your code here

Hint

Use an f-string to build the scope string with the resource group and storage account variables.

4

COMPLETION: Add the event subscription filter to only include Microsoft.Storage.BlobCreated events

Add a key filter to the event_grid_subscription dictionary. Set it to a dictionary with key includedEventTypes set to a list containing the string Microsoft.Storage.BlobCreated.

Azure

resource_group = "myResourceGroup"
storage_account = "mystorageacct"
event_subscription = "myeventsubscription"
endpoint_url = "https://myfunctionapp.azurewebsites.net/runtime/webhooks/eventgrid?functionName=ProcessEvent"
event_grid_subscription = {
    "name": event_subscription,
    "scope": f"/subscriptions/00000000-0000-0000-0000-000000000000/resourceGroups/{resource_group}/providers/Microsoft.Storage/storageAccounts/{storage_account}",
    "destination": {
        "endpointType": "WebHook",
        "properties": {
            "endpointUrl": endpoint_url
        }
    }
}
# Your code here

Hint

Add the filter key at the same level as destination inside the event_grid_subscription dictionary.

Practice

1. What is the main purpose of Azure Event Grid in cloud applications?

easy

A. To route events from sources to event handlers automatically

B. To store large amounts of data for analytics

C. To create virtual machines for compute power

D. To manage user identities and access control

Solution

1. Step 1: Understand Event Grid's role

   Event Grid is designed to route events from sources to handlers automatically, enabling reactive applications.

2. Step 2: Compare with other services

   Other options describe different Azure services: storage, compute, and identity management, not event routing.

3. Final Answer:

   To route events from sources to event handlers automatically -> Option A

4. Quick Check:

   Event routing = To route events from sources to event handlers automatically [OK]

Hint: Event Grid moves events, not data or users [OK]

Common Mistakes:

• Confusing Event Grid with storage services
• Thinking Event Grid manages virtual machines
• Mixing Event Grid with identity services

2. Which Azure CLI command correctly creates an Event Grid subscription named mySub for a topic myTopic?

easy

A. az eventgrid subscription create --topic myTopic --name mySub

B. az eventgrid event-subscription create --name mySub --source-resource-id myTopic

C. az eventgrid topic create --name mySub --source myTopic

D. az eventgrid event-subscription create --name mySub --source-resource-id /subscriptions/.../resourceGroups/.../providers/Microsoft.EventGrid/topics/myTopic

Solution

1. Step 1: Identify correct CLI syntax for event subscription

   The command requires the full resource ID for the source topic using --source-resource-id.

2. Step 2: Evaluate options

   az eventgrid event-subscription create --name mySub --source-resource-id /subscriptions/.../resourceGroups/.../providers/Microsoft.EventGrid/topics/myTopic uses the full resource ID format, which is required. az eventgrid event-subscription create --name mySub --source-resource-id myTopic lacks full resource ID, C creates a topic not subscription, D uses wrong command.

3. Final Answer:

   az eventgrid event-subscription create --name mySub --source-resource-id /subscriptions/.../resourceGroups/.../providers/Microsoft.EventGrid/topics/myTopic -> Option D

4. Quick Check:

   Full resource ID needed for subscription creation [OK]

Hint: Use full resource ID with --source-resource-id for subscriptions [OK]

Common Mistakes:

• Using topic creation command instead of subscription
• Omitting full resource ID in source
• Using incorrect command names

3. Given this Azure CLI command output snippet for an Event Grid subscription:

{
  "destination": {
    "endpointType": "WebHook",
    "properties": {
      "endpointUrl": "https://myapp.com/api/events"
    }
  },
  "filter": {
    "subjectBeginsWith": "orders/",
    "subjectEndsWith": ".json"
  }
}

Which events will be delivered to the webhook endpoint?

medium

A. Only events with subjects exactly 'orders/.json'

B. All events regardless of subject

C. All events with subjects starting with 'orders/' and ending with '.json'

D. Events with subjects containing 'orders/' anywhere

Solution

1. Step 1: Understand subject filters in Event Grid

   The filter uses subjectBeginsWith and subjectEndsWith to select events whose subject starts with 'orders/' and ends with '.json'.

2. Step 2: Analyze options

   All events with subjects starting with 'orders/' and ending with '.json' matches the filter exactly. Only events with subjects exactly 'orders/.json' is too strict (exact match), C ignores filters, D is incorrect because 'contains' is not used.

3. Final Answer:

   All events with subjects starting with 'orders/' and ending with '.json' -> Option C

4. Quick Check:

   Subject filters = startsWith + endsWith [OK]

Hint: Filters combine start and end patterns, not exact or contains [OK]

Common Mistakes:

• Assuming exact subject match required
• Ignoring subject filters and expecting all events
• Confusing contains with beginsWith or endsWith

4. You created an Event Grid subscription but your webhook endpoint is not receiving events. Which of these is the most likely cause?

medium

A. The Event Grid topic does not exist

B. The webhook endpoint URL is incorrect or unreachable

C. You forgot to create an Azure Storage account

D. The subscription filter matches all events

Solution

1. Step 1: Check webhook endpoint accessibility

   If the webhook URL is wrong or the endpoint is down, events cannot be delivered.

2. Step 2: Evaluate other options

   Topic existence is important but usually checked at creation; storage account is unrelated; a filter matching all events would not block delivery.

3. Final Answer:

   The webhook endpoint URL is incorrect or unreachable -> Option B

4. Quick Check:

   Endpoint must be reachable for event delivery [OK]

Hint: Check webhook URL and network access first [OK]

Common Mistakes:

• Assuming storage account is needed for Event Grid
• Ignoring endpoint network issues
• Thinking filters block all events by default

5. You want to route events from multiple Azure Blob Storage accounts to a single Azure Function using Event Grid. What is the best approach to achieve this?

hard

A. Create an Event Grid subscription for each storage account, all pointing to the same Azure Function endpoint

B. Create one Event Grid subscription on one storage account and expect it to receive events from all accounts

C. Use Azure Logic Apps to poll each storage account and forward events to the function

D. Configure the Azure Function to listen directly to all storage accounts without Event Grid

Solution

1. Step 1: Understand Event Grid subscription scope

   Event Grid subscriptions are scoped to a single resource, so each storage account needs its own subscription.

2. Step 2: Evaluate options

   Create an Event Grid subscription for each storage account, all pointing to the same Azure Function endpoint correctly creates multiple subscriptions pointing to one function. Create one Event Grid subscription on one storage account and expect it to receive events from all accounts is invalid because one subscription cannot cover multiple accounts. Use Azure Logic Apps to poll each storage account and forward events to the function adds unnecessary polling. Configure the Azure Function to listen directly to all storage accounts without Event Grid is not supported as functions rely on Event Grid for event routing.

3. Final Answer:

   Create an Event Grid subscription for each storage account, all pointing to the same Azure Function endpoint -> Option A

4. Quick Check:

   One subscription per source resource [OK]

Hint: Each source needs its own subscription to route events [OK]

Common Mistakes:

• Assuming one subscription covers multiple sources
• Using polling instead of event-driven routing
• Expecting Azure Function to listen without Event Grid