Automate periodic deletion of unused Container Registry images

• serverless
• FaaS
• containers
• Python
• Urllib

With intensive use, a Container Registry can quickly become cluttered and store several outdated images.

This tutorial will show you how to periodically remove older images with a specific tag using Serverless Functions, the Scaleway console, and Python’s Urllib.

Before you start

To complete the actions presented below, you must have:

• A Scaleway account logged into the console
• Owner status or IAM permissions allowing you to perform actions in the intended Organization
• A valid API key
• Created a Serverless Functions namespace

Deleting unused images

1. Log into the Scaleway console.

2. Click Functions in the Serverless section of the side menu. The Functions overview page displays.

3. Click the Functions namespace you want to use to create your Function.

4. Click Create a Function. The Function creation wizard displays.

5. From the first drop-down menu, choose to use the online code editor to edit your code directly from your browser in the box provided.

6. From the second drop-down menu, choose python3 as your runtime.

7. Delete what automatically displays in the online code editor.

8. Type the following code into the online code editor:

   import urllib.request
   import os
   import json
   from datetime import datetime, timedelta
   #Configuration
   region=os.environ['REGION']
   auth_token=os.environ['X-AUTH-TOKEN']
   tags_to_keep=int(os.environ['TAGS-TO-KEEP']) # you can also use information passed to the event object
   user_agent = 'Mozilla/5.0 (Windows NT 6.1; Win64; x64)'
   headers={'X-Auth-Token':auth_token, 'User-Agent': user_agent}
   def handle(event, context):
     images_list=[]
     browse=True
     i=1
     # Get the list of all images on all pages
     while browse:
         url=f"https://api.scaleway.com/registry/v1/regions/{region}/images?page_size=100&order_by=created_at_asc&page="+str(i)
         req = urllib.request.Request(url, headers=headers)
         with urllib.request.urlopen(req) as response:
             res = response.read()
             img_list=eval(res)["images"]
         i=i+1
         if not img_list:
             browse=False
         else:
             images_list.extend(img_list)
     tags_to_delete=[]
     # Get all tags by image to delete
     for image in images_list:
         url=f"https://api.scaleway.com/registry/v1/regions/{region}/images/{image['id']}/tags?page_size=100&order_by=created_at_desc"
         req = urllib.request.Request(url, headers=headers)
         with urllib.request.urlopen(req) as response:
             res = response.read()
             tags=eval(res)["tags"]
         i=0
         for tag in tags:
             if i<tags_to_keep:
                 i=i+1
             else:
                 tags_to_delete.append(tag)
     #Delete tags and return their status
     msg=[]
     for tag in tags_to_delete:
         tag_id=tag['id']
         url=f"https://api.scaleway.com/registry/v1/regions/{region}/tags/{tag_id}"
         req = urllib.request.Request(url, headers=headers,method="DELETE")
         with urllib.request.urlopen(req) as response:
             res = response.read()
             msg.append(json.loads(res.decode("utf-8")))
     return {
         "body": {
             "message":msg
         },
         "statusCode": 200,
     }
   

9. Choose a name for your Function. The name must only contain alphanumeric characters.

10. Choose the resources to be allocated to your Function at runtime. These define the performance characteristics of your Function.

11. Set your scaling preferences, or leave them at default values. The Scaleway platform autoscales the number of available Instances of your Function to match the incoming load, depending on the settings you define here.

12. Define the following Environment Variables for your Function:

    Key	Value
    REGION	The Region in which your Registry is located. (eg: fr-par)
    TAGS-TO-KEEP	The number of Image tags you want to keep

13. Define the following Secrets as secret environment variables for your Function:

    Key	Value
    X-AUTH-TOKEN	Your API secret key

14. Set the privacy policy to Private.

15. Deploy the Function by clicking Create a Function. The list of your functions displays.

Configuring a trigger

A trigger allows you to invoke functions by handling events coming from other sources, such as CRON.

1. Click on the name of your newly created function. The functions overview displays.
2. Click the Triggers tab to display the triggers configuration of your function.
3. Click Create a new trigger. A pop-up displays.
4. Enter the details for your new trigger:
   • Enter a name for the trigger.
   • Select the CRON type.
   • Enter the UNIX schedule for the CRON.
     Note

     For example 0 2 * * * will make the function run every day at 2 am.

   • Paste your JSON arguments.
5. Click Create new trigger to create it. The newly created trigger displays in the list of your triggers.