Function Compute:Configure a CDN trigger

Use cases

Example scenario

This guide uses Object Storage Service (OSS) as the origin server. Create a bucket in the OSS console, get its domain name to use as the origin server, then add an accelerated domain name for that origin. For instructions on changing the origin server type, see Configure an origin server.

Alibaba Cloud CDN supports multiple origin server types: OSS domain names, IP addresses, origin domain names, and Function Compute domain names. In multi-origin scenarios, assign primary/secondary priority and weight values to balance load across origin servers.

Prerequisites

Before you begin, ensure that you have:

• A Function Compute function (Create a function)

• An OSS bucket (Create a bucket)

• A CDN-accelerated domain name (Add an accelerated domain name)

Step 1: Create a CDN trigger

1. Log in to the Function Compute console. In the left-side navigation pane, click Functions.

2. In the top navigation bar, select a region. On the Functions page, click the function you want to manage.

3. On the function details page, click the Triggers tab, then click Create Trigger.

4. In the Create Trigger panel, configure the following parameters and click OK.

   If this is the first time you create a CDN trigger, click OK in the panel, then click Authorize Now in the dialog that appears. This grants CDN permission to invoke your function.

   Parameter	What to enter	Example
   Trigger type	Select CDN.	CDN
   Name	Enter a name for the trigger.	cdn-trigger
   Version or alias	The default is LATEST. To bind the trigger to a specific version or alias, first select it from the Version Or Alias drop-down list on the function details page. See Manage versions and Manage aliases.	LATEST
   Triggering event	Select the CDN event type that should invoke the function. See CDN event definitions for a description of each type.	CdnDomainStarted
   Triggering event version	Leave as 1.0.0. This is the only supported version.	1.0.0
   Domain name	Enter the CDN-accelerated domain name.	bucket*******.oss-cn-chengdu-internal.aliyuncs.com
   Description	(Optional) Enter a description for the trigger.	cdntrigger
   Role name	Select AliyunCDNEventNotificationRole.	AliyunCDNEventNotificationRole

After the trigger is created, it appears on the Triggers tab. To modify or delete it, see Manage triggers.

Step 2: Configure test parameters

Set up a test event to verify that your function handles CDN events correctly.

1. On the Code tab of the function details page, click the icon next to Test Function and select Configure Test Parameters from the drop-down list.

2. In the Configure Test Parameters panel, select Create New Test Event or Edit Existing Test Event, enter an event name and content, then click OK.

All CDN trigger events share the same top-level structure. Only the eventParameter field varies by event type.

{
    "events": [
        {
            "eventName": "LogFileCreated",
            "eventSource": "cdn",
            "region": "cn-hangzhou",
            "eventVersion": "1.0.0",
            "eventTime": "2018-06-14T15:31:49+08:00",
            "traceId": "c6459282-6a4d-4413-894c-e4ea3968****",
            "userIdentity": {
                "aliUid": "164901546557****"
            },
            "resource": {
                "domain": "example.com"
            },
            "eventParameter": {
                "domain": "example.com",
                "startTime": 1528959600,
                "endTime": 1528959900,
                "fileSize": 1788115,
                "filePath": "http://cdnlog.cn-hangzhou.oss.aliyun-inc.com/www.aliyun.com/2017_12_27/www.aliyun.com_2017_12_27_0800_0900.gz?OSSAccessKeyId=xxxx&Expires=xxxx&Signature=xxxx"
            }
        }
    ]
}

{
    "events": [
        {
            "eventName": "CachedObjectsRefreshed",
            "eventVersion": "1.0.0",
            "eventSource": "cdn",
            "region": "cn-hangzhou",
            "eventTime": "2018-03-16T14:19:55+08:00",
            "traceId": "cf89e5a8-7d59-4bb5-a33e-4c3d08e2****",
            "resource": {
                "domain": "example.com"
            },
            "eventParameter": {
                "domain": "example.com",
                "taskId": 2089687230,
                "objectType": "File",
                "objectPath": [
                    "/2018/03/16/13/33b430c57e7.mp4",
                    "/2018/03/16/14/4ff6b9bd54d.mp4"
                ],
                "createTime": 1521180769,
                "completeTime": 1521180777
            },
            "userIdentity": {
                "aliUid": "164901546557****"
            }
        }
    ]
}

{
    "events": [
        {
            "eventName": "CdnDomainStarted",
            "eventVersion": "1.0.0",
            "eventSource": "cdn",
            "region": "cn-hangzhou",
            "eventTime": "2018-03-16T14:19:55+08:00",
            "traceId": "cf89e5a8-7d59-4bb5-a33e-4c3d08e2****",
            "resource": {
                "domain": "example.com"
            },
            "eventParameter": {
                "domain": "example.com",
                "status": "online"
            },
            "userIdentity": {
                "aliUid": "164901546557****"
            }
        }
    ]
}

{
    "events": [
        {
            "eventName": "CdnDomainAdded",
            "eventVersion": "1.0.0",
            "eventSource": "cdn",
            "region": "cn-hangzhou",
            "eventTime": "2018-03-16T14:19:55+08:00",
            "traceId": "cf89e5a8-7d59-4bb5-a33e-4c3d08e2****",
            "resource": {
                "domain": "example.com"
            },
            "eventParameter": {
                "domain": "example.com"
            },
            "userIdentity": {
                "aliUid": "164901546557****"
            }
        }
    ]
}

Step 3: Write and test the function code

After creating the trigger, write the function code and verify it handles each event type correctly. In production, the trigger invokes the function automatically when a CDN event occurs.

1. On the Code tab, write the code in the editor and click Deploy Code. The following Python example shows how to handle each CDN event type:

   # -*- coding: utf-8 -*-
   import logging
   import json
   
   logger = logging.getLogger("cdn-sample")
   
   def handler(event, context):
       evt = json.loads(event)
       eventObj = evt["events"][0]
       eventName = eventObj['eventName']
       info = ""
       eventParam = eventObj['eventParameter']
       domain = eventParam['domain']
       if eventName == "CachedObjectsRefreshed" or eventName == "CachedObjectsPushed":
           objPathList = eventParam['objectPath']
           info = ",".join(objPathList)
       elif eventName == "LogFileCreated":
           info = eventParam['filePath']
       elif eventName == "CdnDomainStarted" or eventName == "CdnDomainStopped":
           # Your business logic here
           pass
       elif eventName == "CdnDomainAdded" or eventName == "CdnDomainDeleted":
           # Your business logic here
           pass
       return f"eventName:{eventName}, domain: {domain}, info: {info}"

2. Click Test Function. After execution completes, the result appears above the Code tab.

What's next

In addition to the Function Compute console, configure triggers using:

• Serverless Devs: See Common commands of Serverless Devs.

• SDKs: See SDKs.

To modify or delete an existing trigger, see Manage triggers.