(lambda): Retain Existing Lambda Aliases When Adding an Alias to Version

Would like to manage multiple Lambda Alias from CDK deploy. We want to update an Alias to point to a specific version without deleting existing Aliases.

Whenever we try to add an alias to a Lambda Version, it deletes existing Aliases:

 lambdaFunction.currentVersion.addAlias( <alias name>,{
                        description: DATETIME_ISO
                    })

Use Case

We want to manage multiple aliases for a single lambda. We will deploy multiple versions, but when we “release” we will point the alias(es) to a specific version.

example of what we want: versions deployed 29 28 <- QA 27 26 25 <- DEV 24

Proposed solution

Add an Alias removal policy

a removal policy when adding an alias
cdkLambda.Version
           .fromVersionArn(...get function version...)
           .addAlias( <aliasName>, {

                        description: CDK_CONFIG.DATETIME_ISO
                           ...
                       retentionPolicy: cdkLambda.Alias.RentionPolicy.RETAIN_OTHER_ALIASES
})
  

Other

Example of my cdk code to deploy lambda:

const lambda = require("@aws-cdk/aws-lambda");

const lambdaFunction = new lambda.Function(this, `lambda-${CDK_CONFIG.ENV_LOWER}`, {
            functionName: `${CDK_CONFIG.FUNCTION_NAME}`,
            runtime: lambda.Runtime.NODEJS_12_X,
            code: lambda.Code.fromAsset(`../${CDK_CONFIG.FUNCTION_NAME}.zip`),
            handler: "src/index.handler",
            description: CDK_CONFIG.DATETIME_ISO,
            currentVersionOptions: {
                removalPolicy: cdk.RemovalPolicy.RETAIN,
                // codeSha256:
            },
            timeout: CDK_CONFIG.LAMBDA_TIMEOUT,
            memorySize: CDK_CONFIG.LAMBDA_MEMORY_SIZE,
            vpc: lambdaVpc,

            vpcSubnets: {
                subnets: [
                    {subnetId: cdk.Fn.importValue("k8s-subnet-a-lambda")},
                    {subnetId: cdk.Fn.importValue("k8s-subnet-b-lambda")},
                ]
            },
            securityGroups: [
                {securityGroupId: "a"},
                {securityGroupId: "b"},
                {securityGroupId: "c"},
            ],

            environment: {
                ENVIRONMENT: CDK_CONFIG.ENV_UPPER,
                LOG_LEVEL: CDK_CONFIG.LOG_LEVEL
            },
        });

if ( updateAliasToThisVersion ) {
 lambdaFunction
                    .currentVersion
                    .addAlias(CDK_CONFIG.ENV_UPPER ,{
                        description: CDK_CONFIG.DATETIME_ISO
                    })
} 

• 👋 I may be able to implement this feature request
• ⚠️ This feature might incur a breaking change

---

This is a 🚀 Feature Request

[snowe2010]

It seems like (alias.node.defaultChild as CfnResource).applyRemovalPolicy(RemovalPolicy.RETAIN); might work for our use case.

[snowe2010]

@rix0rrr Our team’s account manager (A. Langford) had said that the cdk team was working on this issue. Our problem is not solved with separate stacks. We want to retain an alias for every version that we deploy (we deploy hundreds of versions for a single stack, never updating old versions). Are you saying that setting the retention policy will be enough to accomplish that?