tencent cloud

Overview

CDN cache purge is a data purge feature provided by COS based on the SCF service. It can automatically purge the data cached on CDN edge nodes. After you add a trigger rule for a bucket, when a file is updated to the bucket, the SCF function preconfigured by COS will be automatically triggered to purge the cached data.

Note：

• If you added a cache purge rule for your bucket in the COS console, the resulting purge function will also appear in the SCF console. Do not delete this function; otherwise, your rule may not take effect.
• Regions where SCF is available support CDN cache purge, including Guangzhou, Shanghai, Beijing, Chengdu, Hong Kong (China), Singapore, Mumbai, Toronto, and Silicon Valley. For more supported regions, see Serverless Cloud Function.
• CDN cache purge may fail due to factors such as unstable network connection. In these cases, you can click View Log for the function created in the COS console to enter the SCF console and view the error log details for troubleshooting.
• The CDN cache purge feature depends on the SCF service, which provides a free tier. Excessive usage will be billed at SCF prices. For more information, see Pricing. For this feature, the more often you purge the cache, the more invocations you will need to use.

Directions

1. Log in to the COS console.
2. Click Bucket List on the left sidebar and click the name of the target bucket.
3. Click Function Service > CDN Cache Purge Function on the left sidebar.
   

   Note：

   If you haven't activated SCF, go to the SCF console to activate it and authorize the service as instructed.

4. Click Add Function and configure the following in the pop-up window:
   
   • Function Name: It uniquely identifies a function and cannot be modified after being set. You can view the function in the SCF console.
   • Event Type: An event is an operation that triggers SCF. Take upload as an example. You can initiate an upload by calling the PUT Object or Post Object API. If you select PUT as the event type, only uploads through the PUT Object API can trigger the function to purge the cache on CDN edge nodes.
   • Trigger Condition: You can specify the file source scope of the triggered files, such as all buckets, specified prefix, or specified suffix. After you specify a prefix or suffix, the rule only applies to the matched file sources.
   • Specified Domain: Specify the CDN domain name to be purged.
   • SCF Authorization: CDN cache purge requires authorizing SCF to call the CDN API PurgeUrlsCache. In this way, SCF can replace your CDN cache with the latest data CDN pulls from the COS origin.
5. Click Confirm.

• Click Log to view the historical operations of CDN cache purge.
• Click Delete to delete an unwanted CDN cache purge rule.