AWS::Lambda::Function - AWS CloudFormation
SyntaxPropertiesReturn valuesExamples

AWS::Lambda::Function

The AWS::Lambda::Function resource creates a Lambda function. To create a function, you need a deployment package and an execution role. The deployment package is a .zip file archive or container image that contains your function code. The execution role grants the function permission to use AWS services, such as Amazon CloudWatch Logs for log streaming and AWS X-Ray for request tracing.

You set the package type to Image if the deployment package is a container image. For these functions, include the URI of the container image in the Amazon ECR registry in the ImageUri property of the Code property. You do not need to specify the handler and runtime properties.

You set the package type to Zip if the deployment package is a .zip file archive. For these functions, specify the Amazon S3 location of your .zip file in the Code property. Alternatively, for Node.js and Python functions, you can define your function inline in the ZipFile property of the Code property. In both cases, you must also specify the handler and runtime properties.

You can use code signing if your deployment package is a .zip file archive. To enable code signing for this function, specify the ARN of a code-signing configuration. When a user attempts to deploy a code package with UpdateFunctionCode, Lambda checks that the code package has a valid signature from a trusted publisher. The code-signing configuration includes a set of signing profiles, which define the trusted publishers for this function.

When you update a AWS::Lambda::Function resource, CloudFormation calls the UpdateFunctionConfiguration and UpdateFunctionCode Lambda APIs under the hood. Because these calls happen sequentially, and invocations can happen between these calls, your function may encounter errors in the time between the calls. For example, if you remove an environment variable, and the code that references that environment variable in the same CloudFormation update, you may see invocation errors related to a missing environment variable. To work around this, you can invoke your function against a version or alias by default, rather than the $LATEST version.

Note that you configure provisioned concurrency on a AWS::Lambda::Version or a AWS::Lambda::Alias.

For a complete introduction to Lambda functions, see What is Lambda? in the Lambda developer guide.

Syntax

To declare this entity in your AWS CloudFormation template, use the following syntax:

JSON

{
  "Type" : "AWS::Lambda::Function",
  "Properties" : {
      "Architectures" : [ String, ... ],
      "Code" : Code,
      "CodeSigningConfigArn" : String,
      "DeadLetterConfig" : DeadLetterConfig,
      "Description" : String,
      "Environment" : Environment,
      "EphemeralStorage" : EphemeralStorage,
      "FileSystemConfigs" : [ FileSystemConfig, ... ],
      "FunctionName" : String,
      "Handler" : String,
      "ImageConfig" : ImageConfig,
      "KmsKeyArn" : String,
      "Layers" : [ String, ... ],
      "LoggingConfig" : LoggingConfig,
      "MemorySize" : Integer,
      "PackageType" : String,
      "RecursiveLoop" : String,
      "ReservedConcurrentExecutions" : Integer,
      "Role" : String,
      "Runtime" : String,
      "RuntimeManagementConfig" : RuntimeManagementConfig,
      "SnapStart" : SnapStart,
      "Tags" : [ Tag, ... ],
      "Timeout" : Integer,
      "TracingConfig" : TracingConfig,
      "VpcConfig" : VpcConfig
    }
}

Properties

Architectures

The instruction set architecture that the function supports. Enter a string array with one of the valid values (arm64 or x86_64). The default value is x86_64.

Required: No

Type: Array of String

Allowed values: x86_64 | arm64

Minimum: 1

Maximum: 1

Update requires: No interruption

Code

The code for the function. You can define your function code in multiple ways:

  • For .zip deployment packages, you can specify the Amazon S3 location of the .zip file in the S3Bucket, S3Key, and S3ObjectVersion properties.

  • For .zip deployment packages, you can alternatively define the function code inline in the ZipFile property. This method works only for Node.js and Python functions.

  • For container images, specify the URI of your container image in the Amazon ECR registry in the ImageUri property.

Required: Yes

Type: Code

Update requires: No interruption

CodeSigningConfigArn

To enable code signing for this function, specify the ARN of a code-signing configuration. A code-signing configuration includes a set of signing profiles, which define the trusted publishers for this function.

Required: No

Type: String

Pattern: arn:(aws[a-zA-Z-]*)?:lambda:[a-z]{2}((-gov)|(-iso(b?)))?-[a-z]+-\d{1}:\d{12}:code-signing-config:csc-[a-z0-9]{17}

Update requires: No interruption

DeadLetterConfig

A dead-letter queue configuration that specifies the queue or topic where Lambda sends asynchronous events when they fail processing. For more information, see Dead-letter queues.

Required: No

Type: DeadLetterConfig

Update requires: No interruption

Description

A description of the function.

Required: No

Type: String

Maximum: 256

Update requires: No interruption

Environment

Environment variables that are accessible from function code during execution.

Required: No

Type: Environment

Update requires: No interruption

EphemeralStorage

The size of the function's /tmp directory in MB. The default value is 512, but it can be any whole number between 512 and 10,240 MB.

Required: No

Type: EphemeralStorage

Update requires: No interruption

FileSystemConfigs

Connection settings for an Amazon EFS file system. To connect a function to a file system, a mount target must be available in every Availability Zone that your function connects to. If your template contains an AWS::EFS::MountTarget resource, you must also specify a DependsOn attribute to ensure that the mount target is created or updated before the function.

For more information about using the DependsOn attribute, see DependsOn Attribute.

Required: No

Type: Array of FileSystemConfig

Maximum: 1

Update requires: No interruption

FunctionName

The name of the Lambda function, up to 64 characters in length. If you don't specify a name, AWS CloudFormation generates one.

If you specify a name, you cannot perform updates that require replacement of this resource. You can perform updates that require no or some interruption. If you must replace the resource, specify a new name.

Required: No

Type: String

Minimum: 1

Update requires: Replacement

Handler

The name of the method within your code that Lambda calls to run your function. Handler is required if the deployment package is a .zip file archive. The format includes the file name. It can also include namespaces and other qualifiers, depending on the runtime. For more information, see Lambda programming model.

Required: No

Type: String

Pattern: ^[^\s]+$

Maximum: 128

Update requires: No interruption

ImageConfig

Configuration values that override the container image Dockerfile settings. For more information, see Container image settings.

Required: No

Type: ImageConfig

Update requires: No interruption

KmsKeyArn

The ARN of the AWS Key Management Service (AWS KMS) customer managed key that's used to encrypt your function's environment variables. When Lambda SnapStart is activated, Lambda also uses this key is to encrypt your function's snapshot. If you deploy your function using a container image, Lambda also uses this key to encrypt your function when it's deployed. Note that this is not the same key that's used to protect your container image in the Amazon Elastic Container Registry (Amazon ECR). If you don't provide a customer managed key, Lambda uses a default service key.

Required: No

Type: String

Pattern: ^(arn:(aws[a-zA-Z-]*)?:[a-z0-9-.]+:.*)|()$

Update requires: No interruption

Layers

A list of function layers to add to the function's execution environment. Specify each layer by its ARN, including the version.

Required: No

Type: Array of String

Update requires: No interruption

LoggingConfig

The function's Amazon CloudWatch Logs configuration settings.

Required: No

Type: LoggingConfig

Update requires: No interruption

MemorySize

The amount of memory available to the function at runtime. Increasing the function memory also increases its CPU allocation. The default value is 128 MB. The value can be any multiple of 1 MB. Note that new AWS accounts have reduced concurrency and memory quotas. AWS raises these quotas automatically based on your usage. You can also request a quota increase.

Required: No

Type: Integer

Minimum: 128

Maximum: 10240

Update requires: No interruption

PackageType

The type of deployment package. Set to Image for container image and set Zip for .zip file archive.

Required: No

Type: String

Allowed values: Image | Zip

Update requires: No interruption

RecursiveLoop

The status of your function's recursive loop detection configuration.

When this value is set to Allowand Lambda detects your function being invoked as part of a recursive loop, it doesn't take any action.

When this value is set to Terminate and Lambda detects your function being invoked as part of a recursive loop, it stops your function being invoked and notifies you.

Required: No

Type: String

Allowed values: Allow | Terminate

Update requires: No interruption

ReservedConcurrentExecutions

The number of simultaneous executions to reserve for the function.

Required: No

Type: Integer

Minimum: 0

Update requires: No interruption

Role

The Amazon Resource Name (ARN) of the function's execution role.

Required: Yes

Type: String

Pattern: ^arn:(aws[a-zA-Z-]*)?:iam::\d{12}:role/?[a-zA-Z_0-9+=,.@\-_/]+$

Update requires: No interruption

Runtime

The identifier of the function's runtime. Runtime is required if the deployment package is a .zip file archive. Specifying a runtime results in an error if you're deploying a function using a container image.

The following list includes deprecated runtimes. Lambda blocks creating new functions and updating existing functions shortly after each runtime is deprecated. For more information, see Runtime use after deprecation.

For a list of all currently supported runtimes, see Supported runtimes.

Required: No

Type: String

Allowed values: nodejs | nodejs4.3 | nodejs6.10 | nodejs8.10 | nodejs10.x | nodejs12.x | nodejs14.x | nodejs16.x | java8 | java8.al2 | java11 | python2.7 | python3.6 | python3.7 | python3.8 | python3.9 | dotnetcore1.0 | dotnetcore2.0 | dotnetcore2.1 | dotnetcore3.1 | dotnet6 | dotnet8 | nodejs4.3-edge | go1.x | ruby2.5 | ruby2.7 | provided | provided.al2 | nodejs18.x | python3.10 | java17 | ruby3.2 | ruby3.3 | python3.11 | nodejs20.x | provided.al2023 | python3.12 | java21

Update requires: No interruption

RuntimeManagementConfig

Sets the runtime management configuration for a function's version. For more information, see Runtime updates.

Required: No

Type: RuntimeManagementConfig

Update requires: No interruption

SnapStart

The function's AWS Lambda SnapStart setting.

Required: No

Type: SnapStart

Update requires: No interruption

Tags

A list of tags to apply to the function.

Note

You must have the lambda:TagResource, lambda:UntagResource, and lambda:ListTags permissions for your IAM principal to manage the AWS CloudFormation stack. If you don't have these permissions, there might be unexpected behavior with stack-level tags propagating to the resource during resource creation and update.

Required: No

Type: Array of Tag

Update requires: No interruption

Timeout

The amount of time (in seconds) that Lambda allows a function to run before stopping it. The default is 3 seconds. The maximum allowed value is 900 seconds. For more information, see Lambda execution environment.

Required: No

Type: Integer

Minimum: 1

Update requires: No interruption

TracingConfig

Set Mode to Active to sample and trace a subset of incoming requests with X-Ray.

Required: No

Type: TracingConfig

Update requires: No interruption

VpcConfig

For network connectivity to AWS resources in a VPC, specify a list of security groups and subnets in the VPC. When you connect a function to a VPC, it can access resources and the internet only through that VPC. For more information, see Configuring a Lambda function to access resources in a VPC.

Required: No

Type: VpcConfig

Update requires: No interruption

Return values

Ref

When you pass the logical ID of this resource to the intrinsic Ref function, Ref returns the resource name.

For more information about using the Ref function, see Ref.

Fn::GetAtt

The Fn::GetAtt intrinsic function returns a value for a specified attribute of this type. The following are the available attributes and sample return values.

For more information about using the Fn::GetAtt intrinsic function, see Fn::GetAtt.

Arn

The Amazon Resource Name (ARN) of the function.

SnapStartResponse.ApplyOn

Property description not available.

SnapStartResponse.OptimizationStatus

Property description not available.

Examples

Function

Create a Node.js function.

JSON

"AMIIDLookup": {
    "Type": "AWS::Lambda::Function",
    "Properties": {
        "Handler": "index.handler",
        "Role": {
            "Fn::GetAtt": [
                "LambdaExecutionRole",
                "Arn"
            ]
        },
        "Code": {
            "S3Bucket": "amzn-s3-demo-bucket",
            "S3Key": "amilookup.zip"
        },
        "Runtime": "nodejs20.x",
        "Timeout": 25,
        "TracingConfig": {
            "Mode": "Active"
        }
    }
}

Inline Function

Inline Node.js function that lists Amazon S3 buckets in us-east-1 . Before using this example, make sure that your execution role has Amazon S3 read permissions.

YAML

AWSTemplateFormatVersion: '2010-09-09'
Description: Lambda function ListBucketsCommand.
Resources:
  primer:
    Type: AWS::Lambda::Function
    Properties:
      Runtime: nodejs20.x
      Role: arn:aws:iam::111122223333:role/lambda-role
      Handler: index.handler
      Code:
        ZipFile: |
          const { S3Client, ListBucketsCommand } = require("@aws-sdk/client-s3");
          const s3 = new S3Client({ region: "us-east-1" }); // replace "us-east-1" with your AWS Region

          exports.handler = async function(event) {
            const command = new ListBucketsCommand({});
            const response = await s3.send(command);
            return response.Buckets;
          };
      Description: List Amazon S3 buckets in us-east-1.
      TracingConfig:
        Mode: Active

VPC Function

Function connected to a VPC.

YAML

AWSTemplateFormatVersion: '2010-09-09'
Description: VPC function.
Resources:
  Function:
    Type: AWS::Lambda::Function
    Properties:
      Handler: index.handler
      Role: arn:aws:iam::111122223333:role/lambda-role
      Code:
        S3Bucket: amzn-s3-demo-bucket
        S3Key: function.zip
      Runtime: nodejs20.x
      Timeout: 5
      TracingConfig:
        Mode: Active
      VpcConfig:
        SecurityGroupIds:
          - sg-085912345678492fb
        SubnetIds:
          - subnet-071f712345678e7c8
          - subnet-07fd123456788a036