Function Compute:Use versions and aliases to implement canary release

Canary release process

Before you start

• A function is created. For more information, see Create a function.

Step 1: Prepare and test a function

When you create a function for the first time, the version of the function is LATEST. You can debug the function of the LATEST version until the function becomes stable. You can also invoke the function of the LATEST version in the Function Compute console.

1. Log on 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 that you want to manage.

3. On the Function Details page, click the Code tab.

4. In the code editor, modify the code to view the version of the function, click Deploy, and then click Test Function.

   The following sample code is used to check the function version.

   Node.js

   module.exports.handler = function(eventBuf, context, callback) {
    var qualifier = context['service']['qualifier']
    var versionId = context['service']['versionId']
    console.log('Qualifier from context:', qualifier);
    console.log('VersionId from context: ', versionId);
    callback(null, qualifier);
   };

   Python

   # -*- coding: utf-8 -*-
   
   def handler(event, context):
     qualifier = context.service.qualifier
     versionId = context.service.version_id
     print('Qualifier from context:' + qualifier)
     print('VersionId from context:' + versionId)
     return 'hello world'

   PHP

   <?php
   function handler($event, $context) {
     $qualifier = $context["service"]["qualifier"];
     $versionId = $context["service"]["versionId"];
     print($qualifier);
     print($versionId);
   
       return "hello world";
   }

   C#

   using System;
   using System.IO;
   using Aliyun.Serverless.Core;
   using Microsoft.Extensions.Logging;
   
   namespace Desktop
   {
   
       class Program
       {
           static void Main(string[] args)
           {
               Console.WriteLine("Hello World!");
           }
       }
   
       class App
       {
           public string Handler(Stream input, IFcContext context)
           {
               ILogger logger = context.Logger;
               var qualifier = context.ServiceMeta.Qualifier;
               var versionId = context.ServiceMeta.VersionId;
               logger.LogInformation("Qualifier from context: {0}", qualifier);
               logger.LogInformation("versionId from context: {0}", versionId);
               return "hello word";
           }
       }
   }

   After the execution is complete, you can view the log output. In the log output, you can find that the value of the qualifier parameter, which indicates the version information, is LATEST. This means the executed function belongs to the function of the LATEST version.

Step 2: Publish and test a version

When the function proves to be stable, you can publish this version and use it to process online requests. For more information, see Publish a version.

After a new version is published, you can execute it in the Function Compute console.

1. Log on 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 that you want to manage.

3. On the Function Details page, switch to the Versions tab page and click the version that you want to manage.

4. On the page that appears, click the Code tab, and then click Test Function.

   After the function is executed, you can view the execution log output. In the log output, you can find that the value of the qualifier parameter, which indicates the version information, is 1 and the value of the versionId parameter, which indicates the version ID, is 1. The log output shows that the executed function is of Version 1.

Step 3: Use an alias to divert traffic

After a version is published, you can create an alias and point the alias to the version. When this version is updated, you can point the alias to the updated version. The caller only needs to use the correct alias and does not need to be aware of the specific versions of the function. For more information about how to create an alias, see Create an alias.

After the alias is created, you can verify whether the correct version of the function is executed in the Function Compute console.

In this topic, the alias alias1 points to version 1.

1. Log on 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 that you want to manage.

3. On the Function Details page, switch to the Aliases tab page and click the alias that you want to view.

4. On the page that appears, click the Test tab, and then click Test Function.

   After the execution is complete, you can view the log output. In the log output, you can find that the value of the qualifier parameter, which indicates the version information, is alias1 and the value of the versionId parameter, which indicates the version ID, is 1. The log shows the function of the alias1 alias is invoked and the alias points to Version 1.

After a new version is developed, you can use the canary release feature to ensure that the new version is stable before it is officially rolled out.

1. Publish Version 2 as a new version. For more information, see Publish a version.

   After the version is published, you can view the latest version in the version list.

2. On the Function Details page, switch to the Aliases tab page. Find the alias that you want to manage and click Modify in the Actions column.

3. In the alias editing panel, set Version 2 as Canary Release Version, configure Canary Release Version Weight, and then click OK.

   After the canary release version becomes stable, you can switch all online traffic to Version 2.

FAQ

How do I check the function version of an invocation?

More information

For more information about how to manage versions and aliases, see Manage versions and Manage aliases.