Dealing CloudEvents with Azure Functions for Azure EventGrid

01-dotnet-add-package.sh

dotnet add package Azure.Messaging.EventGrid --version 4.0.0-beta.4

02-az-extension-add.sh

az extension add -n eventgrid

03-get-endpoint.sh

endpoint=$(az eventgrid topic show \
    -g <resource_group_name> \
    -n <eventgrid_topic_name> \
    --query "endpoint" -o tsv)

04-get-access-key.sh

id=$(az eventgrid topic show \
    -g <resource_group_name> \
    -n <eventgrid_topic_name> \
    --query "id" -o tsv)

key=$(az rest \
    -m POST \
    -u "https://management.azure.com$id/listKeys?api-version=2020-06-01" \
    --query "key1" -o tsv)

05-create-publisher.cs

var topicEndpoint = new Uri("<endpoint>");
var credential = new AzureKeyCredential("<key>");
var publisher = new EventGridPublisherClient(topicEndpoint, credential);

06-publish-event.cs

var source = "<source>";
var type = "<type>";
var dataContentType = "application/cloudevents+json";

var data = new MyData() { Hello = "World" };

var @event = new CloudEvent(source, type, data, dataContentType);
var events = new List<CloudEvent>() { @event };

await publisher.SendEventsAsync(events).ConfigureAwait(false);

07-validate-request.cs

[FunctionName("HttpTrigger")]
public static async Task<IActionResult> Run(
    [HttpTrigger(AuthorizationLevel.Anonymous, "POST", "OPTIONS", Route = "handler")] HttpRequest req,
    ILogger log)
{
    if (HttpMethods.IsOptions(req.Method))
    {
        string header = req.Headers["WebHook-Request-Origin"];
        req.HttpContext.Response.Headers.Add("Webhook-Allowed-Origin", header);

        return new OkResult();
    }

    ...
}

08-handle-event.cs

[FunctionName("HttpTrigger")]
public static async Task<IActionResult> Run(
    [HttpTrigger(AuthorizationLevel.Anonymous, "POST", "OPTIONS", Route = "handler")] HttpRequest req,
    ILogger log)
{
    if (HttpMethods.IsOptions(req.Method))
    {
        ...
    }

    using (var reader = new StreamReader(req.Body))
    {
        var payload = await reader.ReadToEndAsync().ConfigureAwait(false);
        var events = CloudEvent.Parse(payload);

        foreach (var @event in events)
        {
            var timestamp = @event.Time;
            var data = await @event.GetDataAsync<MyData>().ConfigureAwait(false);
            ...
        }
    }

    return new OkResult();
}