Trigger an Azure Function with a GitHub event

Completed

The GitHub Gollum event enables you to listen for wiki updates. When this event occurs, your Azure HttpTrigger function is triggered, and you can parse the payload to retrieve and process the data that was sent.

You've shown your IT department that you can listen for Gollum events on your company's GitHub repository by setting up a webhook. You've also demonstrated how Azure Function apps enable you to run code when a function receives a webhook request.

In this unit, we'll examine the payload from the Gollum event so we can update our function to parse it correctly.

Gollum event payload

The payload for the Gollum event contains the following items:

• pages that were updated. Each page includes the following information:
  • page_name Name of the page.
  • title Current page title.
  • action Action that was performed on the page - created or edited.
  • html_url HTML wiki page.
• repository information about the repository containing the wiki page, including:
  • name Name of the repository.
  • owner Details of the owner of the repository.
  • html_url Address of the repository.
• sender information about the user that raised the event that caused the webhook to fire.

For example, a payload might look like the following code.

"pages": [
    {
        "page_name": "Home",
        "title": "Home",
        "summary": null,
        "action": "edited",
        "sha": "562362bc141b9e2db1fb971e1ecb4fd0b7457f68",
        "html_url": "https://github.com/testrepo/Hello-World/wiki/Home"
    }
],
"repository": {
    ...
    "name": "testrepo",
    ...
    "owner": {
        ...
    },
    "html_url": "https://github.com/...",
    ...
},
"sender": {
    "login": "..."
    ...
}

This information is passed as the body of an HTTP POST request. We'll need to update our function logic to parse and process this information correctly.

Parse information from the Gollum event

Recall that the webhook runs when a specific event occurs. The webhook then sends a request to the URL where your Azure Functions code is set up to listen, using the URL for your function. The payload is passed to the Azure Function. Your function can parse the request body to extract the fields from the payload, and take the appropriate actions.

The following example retrieves the repository name from the payload. The event type is available in the x-github-event request header. This data is output in the following function response.

if (req.body.repository.name){
    context.res = {
        body: "Repository is: " + req.body.repository.name + ", Event Type is: " + req.headers['x-github-event']
    };
}

In the next exercise, we'll update your function code to be able to handle an incoming Gollum event.