Deploy Go Lambda functions with container images

There are two ways to build a container image for a Go Lambda function:

• Using an AWS OS-only base image

  Go is implemented differently than other managed runtimes. Because Go compiles natively to an executable binary, it doesn't require a dedicated language runtime. Use an OS-only base image to build Go images for Lambda. To make the image compatible with Lambda, you must include the aws-lambda-go/lambda package in the image.

• Using a non-AWS base image

  You can use an alternative base image from another container registry, such as Alpine Linux or Debian. You can also use a custom image created by your organization. To make the image compatible with Lambda, you must include the aws-lambda-go/lambda package in the image.

Tip

To reduce the time it takes for Lambda container functions to become active, see Use multi-stage builds in the Docker documentation. To build efficient container images, follow the Best practices for writing Dockerfiles.

This page explains how to build, test, and deploy container images for Lambda.

AWS base images for deploying Go functions

Go is implemented differently than other managed runtimes. Because Go compiles natively to an executable binary, it doesn't require a dedicated language runtime. Use an OS-only base image to deploy Go functions to Lambda.

Name	Identifier	Operating system	Deprecation date	Block function create	Block function update
OS-only Runtime	provided.al2023	Amazon Linux 2023	Not scheduled	Not scheduled	Not scheduled
OS-only Runtime	provided.al2	Amazon Linux 2	Not scheduled	Not scheduled	Not scheduled

Amazon Elastic Container Registry Public Gallery: gallery.ecr.aws/lambda/provided

Go runtime interface client

The aws-lambda-go/lambda package includes an implementation of the runtime interface. For examples of how to use aws-lambda-go/lambda in your image, see Using an AWS OS-only base image or Using a non-AWS base image.

Using an AWS OS-only base image

Go is implemented differently than other managed runtimes. Because Go compiles natively to an executable binary, it doesn't require a dedicated language runtime. Use an OS-only base image to build container images for Go functions.

Tags	Runtime	Operating system	Dockerfile	Deprecation
al2023	OS-only Runtime	Amazon Linux 2023	Dockerfile for OS-only Runtime on GitHub	Not scheduled
al2	OS-only Runtime	Amazon Linux 2	Dockerfile for OS-only Runtime on GitHub	Not scheduled

For more information about these base images, see provided in the Amazon ECR public gallery.

You must include the aws-lambda-go/lambda package with your Go handler. This package implements the programming model for Go, including the runtime interface.

Prerequisites

To complete the steps in this section, you must have the following:

• Go

• Docker

• AWS Command Line Interface (AWS CLI) version 2

Creating an image from the provided.al2023 base image

To build and deploy a Go function with the provided.al2023 base image

1. Create a directory for the project, and then switch to that directory.

   mkdir hello
   cd hello

2. Initialize a new Go module.

   go mod init example.com/hello-world

3. Add the lambda library as a dependency of your new module.

   go get github.com/aws/aws-lambda-go/lambda

4. Create a file named main.go and then open it in a text editor. This is the code for the Lambda function. You can use the following sample code for testing, or replace it with your own.

   package main
   
   import (
   	"context"
   	"github.com/aws/aws-lambda-go/events"
   	"github.com/aws/aws-lambda-go/lambda"
   )
   
   func handler(ctx context.Context, event events.APIGatewayProxyRequest) (events.APIGatewayProxyResponse, error) {
   	response := events.APIGatewayProxyResponse{
   		StatusCode: 200,
   		Body:       "\"Hello from Lambda!\"",
   	}
   	return response, nil
   }
   
   func main() {
   	lambda.Start(handler)
   }

5. Use a text editor to create a Dockerfile in your project directory.

   • The following example Dockerfile uses a multi-stage build. This allows you to use a different base image in each step. You can use one image, such as a Go base image, to compile your code and build the executable binary. You can then use a different image, such as provided.al2023, in the final FROM statement to define the image that you deploy to Lambda. The build process is separated from the final deployment image, so the final image only contains the files needed to run the application.

   • You can use the optional lambda.norpc tag to exclude the Remote Procedure Call (RPC) component of the lambda library. The RPC component is only required if you are using the deprecated Go 1.x runtime. Excluding the RPC reduces the size of the deployment package.

   • Note that the example Dockerfile does not include a USER instruction. When you deploy a container image to Lambda, Lambda automatically defines a default Linux user with least-privileged permissions. This is different from standard Docker behavior which defaults to the root user when no USER instruction is provided.

   Example — Multi-stage build Dockerfile

   Note

   Make sure that the version of Go that you specify in your Dockerfile (for example, golang:1.20) is the same version of Go that you used to create your application.

   FROM golang:1.20 as build
   WORKDIR /helloworld
   # Copy dependencies list
   COPY go.mod go.sum ./
   # Build with optional lambda.norpc tag
   COPY main.go .
   RUN go build -tags lambda.norpc -o main main.go
   # Copy artifacts to a clean image
   FROM public.ecr.aws/lambda/provided:al2023
   COPY --from=build /helloworld/main ./main
   ENTRYPOINT [ "./main" ]

6. Build the Docker image with the docker build command. The following example names the image docker-image and gives it the test tag.

   docker build --platform linux/amd64 -t docker-image:test .

   Note

   The command specifies the --platform linux/amd64 option to ensure that your container is compatible with the Lambda execution environment regardless of the architecture of your build machine. If you intend to create a Lambda function using the ARM64 instruction set architecture, be sure to change the command to use the --platform linux/arm64 option instead.

(Optional) Test the image locally

Use the runtime interface emulator to locally test your image. The runtime interface emulator is included in the provided.al2023 base image.

To run the runtime interface emulator on your local machine

1. Start the Docker image with the docker run command. Note the following:

   • docker-image is the image name and test is the tag.

   • ./main is the ENTRYPOINT from your Dockerfile.

   docker run -d -p 9000:8080 \
   --entrypoint /usr/local/bin/aws-lambda-rie \
   docker-image:test ./main

   This command runs the image as a container and creates a local endpoint at localhost:9000/2015-03-31/functions/function/invocations.

2. From a new terminal window, post an event to the following endpoint using a curl command:

   curl "http://localhost:9000/2015-03-31/functions/function/invocations" -d '{}'

   This command invokes the function with an empty event and returns a response. Some functions might require a JSON payload. Example:

   curl "http://localhost:9000/2015-03-31/functions/function/invocations" -d '{"payload":"hello world!"}'

3. Get the container ID.

   docker ps

4. Use the docker kill command to stop the container. In this command, replace 3766c4ab331c with the container ID from the previous step.

   docker kill 3766c4ab331c

Deploying the image

To upload the image to Amazon ECR and create the Lambda function

1. Run the get-login-password command to authenticate the Docker CLI to your Amazon ECR registry.

   • Set the --region value to the AWS Region where you want to create the Amazon ECR repository.

   • Replace 111122223333 with your AWS account ID.

   aws ecr get-login-password --region us-east-1 | docker login --username AWS --password-stdin 111122223333.dkr.ecr.us-east-1.amazonaws.com

2. Create a repository in Amazon ECR using the create-repository command.

   aws ecr create-repository --repository-name hello-world --region us-east-1 --image-scanning-configuration scanOnPush=true --image-tag-mutability MUTABLE

   Note

   The Amazon ECR repository must be in the same AWS Region as the Lambda function.

   If successful, you see a response like this:

   {
       "repository": {
           "repositoryArn": "arn:aws:ecr:us-east-1:111122223333:repository/hello-world",
           "registryId": "111122223333",
           "repositoryName": "hello-world",
           "repositoryUri": "111122223333.dkr.ecr.us-east-1.amazonaws.com/hello-world",
           "createdAt": "2023-03-09T10:39:01+00:00",
           "imageTagMutability": "MUTABLE",
           "imageScanningConfiguration": {
               "scanOnPush": true
           },
           "encryptionConfiguration": {
               "encryptionType": "AES256"
           }
       }
   }

3. Copy the repositoryUri from the output in the previous step.

4. Run the docker tag command to tag your local image into your Amazon ECR repository as the latest version. In this command:

   • docker-image:test is the name and tag of your Docker image. This is the image name and tag that you specified in the docker build command.

   • Replace <ECRrepositoryUri> with the repositoryUri that you copied. Make sure to include :latest at the end of the URI.

   docker tag docker-image:test <ECRrepositoryUri>:latest

   Example:

   docker tag docker-image:test 111122223333.dkr.ecr.us-east-1.amazonaws.com/hello-world:latest

5. Run the docker push command to deploy your local image to the Amazon ECR repository. Make sure to include :latest at the end of the repository URI.

   docker push 111122223333.dkr.ecr.us-east-1.amazonaws.com/hello-world:latest

6. Create an execution role for the function, if you don't already have one. You need the Amazon Resource Name (ARN) of the role in the next step.

7. Create the Lambda function. For ImageUri, specify the repository URI from earlier. Make sure to include :latest at the end of the URI.

   aws lambda create-function \
     --function-name hello-world \
     --package-type Image \
     --code ImageUri=111122223333.dkr.ecr.us-east-1.amazonaws.com/hello-world:latest \
     --role arn:aws:iam::111122223333:role/lambda-ex

   Note

   You can create a function using an image in a different AWS account, as long as the image is in the same Region as the Lambda function. For more information, see Amazon ECR cross-account permissions.

8. Invoke the function.

   aws lambda invoke --function-name hello-world response.json

   You should see a response like this:

   {
     "ExecutedVersion": "$LATEST", 
     "StatusCode": 200
   }

9. To see the output of the function, check the response.json file.

To update the function code, you must build the image again, upload the new image to the Amazon ECR repository, and then use the update-function-code command to deploy the image to the Lambda function.

Lambda resolves the image tag to a specific image digest. This means that if you point the image tag that was used to deploy the function to a new image in Amazon ECR, Lambda doesn't automatically update the function to use the new image.

To deploy the new image to the same Lambda function, you must use the update-function-code command, even if the image tag in Amazon ECR remains the same. In the following example, the --publish option creates a new version of the function using the updated container image.

aws lambda update-function-code \
  --function-name hello-world \
  --image-uri 111122223333.dkr.ecr.us-east-1.amazonaws.com/hello-world:latest \
  --publish

Using a non-AWS base image

You can build a container image for Go from a non-AWS base image. The example Dockerfile in the following steps uses an Alpine base image.

You must include the aws-lambda-go/lambda package with your Go handler. This package implements the programming model for Go, including the runtime interface.

Prerequisites

To complete the steps in this section, you must have the following:

• Go

• Docker

• AWS Command Line Interface (AWS CLI) version 2

Creating an image from an alternative base image

To build and deploy a Go function with an Alpine base image

1. Create a directory for the project, and then switch to that directory.

   mkdir hello
   cd hello

2. Initialize a new Go module.

   go mod init example.com/hello-world

3. Add the lambda library as a dependency of your new module.

   go get github.com/aws/aws-lambda-go/lambda

4. Create a file named main.go and then open it in a text editor. This is the code for the Lambda function. You can use the following sample code for testing, or replace it with your own.

   package main
   
   import (
   	"context"
   	"github.com/aws/aws-lambda-go/events"
   	"github.com/aws/aws-lambda-go/lambda"
   )
   
   func handler(ctx context.Context, event events.APIGatewayProxyRequest) (events.APIGatewayProxyResponse, error) {
   	response := events.APIGatewayProxyResponse{
   		StatusCode: 200,
   		Body:       "\"Hello from Lambda!\"",
   	}
   	return response, nil
   }
   
   func main() {
   	lambda.Start(handler)
   }

5. Use a text editor to create a Dockerfile in your project directory. The following example Dockerfile uses an Alpine base image. Note that the example Dockerfile does not include a USER instruction. When you deploy a container image to Lambda, Lambda automatically defines a default Linux user with least-privileged permissions. This is different from standard Docker behavior which defaults to the root user when no USER instruction is provided.

   Example Dockerfile

   Note

   Make sure that the version of Go that you specify in your Dockerfile (for example, golang:1.20) is the same version of Go that you used to create your application.

   FROM golang:1.20.2-alpine3.16 as build
   WORKDIR /helloworld
   # Copy dependencies list
   COPY go.mod go.sum ./
   # Build
   COPY main.go .
   RUN go build -o main main.go
   # Copy artifacts to a clean image
   FROM alpine:3.16
   COPY --from=build /helloworld/main /main
   ENTRYPOINT [ "/main" ]

6. Build the Docker image with the docker build command. The following example names the image docker-image and gives it the test tag.

   docker build --platform linux/amd64 -t docker-image:test .

   Note

   The command specifies the --platform linux/amd64 option to ensure that your container is compatible with the Lambda execution environment regardless of the architecture of your build machine. If you intend to create a Lambda function using the ARM64 instruction set architecture, be sure to change the command to use the --platform linux/arm64 option instead.

(Optional) Test the image locally

Use the runtime interface emulator to locally test the image. You can build the emulator into your image or use the following procedure to install it on your local machine.

To install and run the runtime interface emulator on your local machine

1. From your project directory, run the following command to download the runtime interface emulator (x86-64 architecture) from GitHub and install it on your local machine.

   Linux/macOS

   mkdir -p ~/.aws-lambda-rie && \
       curl -Lo ~/.aws-lambda-rie/aws-lambda-rie https://github.com/aws/aws-lambda-runtime-interface-emulator/releases/latest/download/aws-lambda-rie && \
       chmod +x ~/.aws-lambda-rie/aws-lambda-rie

   To install the arm64 emulator, replace the GitHub repository URL in the previous command with the following:

   https://github.com/aws/aws-lambda-runtime-interface-emulator/releases/latest/download/aws-lambda-rie-arm64

   PowerShell

   $dirPath = "$HOME\.aws-lambda-rie"
   if (-not (Test-Path $dirPath)) {
       New-Item -Path $dirPath -ItemType Directory
   }
         
   $downloadLink = "https://github.com/aws/aws-lambda-runtime-interface-emulator/releases/latest/download/aws-lambda-rie"
   $destinationPath = "$HOME\.aws-lambda-rie\aws-lambda-rie"
   Invoke-WebRequest -Uri $downloadLink -OutFile $destinationPath

   To install the arm64 emulator, replace the $downloadLink with the following:

   https://github.com/aws/aws-lambda-runtime-interface-emulator/releases/latest/download/aws-lambda-rie-arm64

2. Start the Docker image with the docker run command. Note the following:

   • docker-image is the image name and test is the tag.

   • /main is the ENTRYPOINT from your Dockerfile.

   Linux/macOS

   docker run --platform linux/amd64 -d -v ~/.aws-lambda-rie:/aws-lambda -p 9000:8080 \
       --entrypoint /aws-lambda/aws-lambda-rie \
       --read-only \
       docker-image:test \
           /main

   PowerShell

   docker run --platform linux/amd64 -d -v "$HOME\.aws-lambda-rie:/aws-lambda" -p 9000:8080 `
   --entrypoint /aws-lambda/aws-lambda-rie `
   --read-only `
   docker-image:test `
       /main

   This command runs the image as a container and creates a local endpoint at localhost:9000/2015-03-31/functions/function/invocations.

   Note

   If you built the Docker image for the ARM64 instruction set architecture, be sure to use the --platform linux/arm64 option instead of --platform linux/amd64.

3. Post an event to the local endpoint.

   Linux/macOS

   In Linux and macOS, run the following curl command:

   curl "http://localhost:9000/2015-03-31/functions/function/invocations" -d '{}'

   This command invokes the function with an empty event and returns a response. If you're using your own function code rather than the sample function code, you might want to invoke the function with a JSON payload. Example:

   curl "http://localhost:9000/2015-03-31/functions/function/invocations" -d '{"payload":"hello world!"}'

   PowerShell

   In PowerShell, run the following Invoke-WebRequest command:

   Invoke-WebRequest -Uri "http://localhost:9000/2015-03-31/functions/function/invocations" -Method Post -Body '{}' -ContentType "application/json"

   This command invokes the function with an empty event and returns a response. If you're using your own function code rather than the sample function code, you might want to invoke the function with a JSON payload. Example:

   Invoke-WebRequest -Uri "http://localhost:9000/2015-03-31/functions/function/invocations" -Method Post -Body '{"payload":"hello world!"}' -ContentType "application/json"

4. Get the container ID.

   docker ps

5. Use the docker kill command to stop the container. In this command, replace 3766c4ab331c with the container ID from the previous step.

   docker kill 3766c4ab331c

Deploying the image

To upload the image to Amazon ECR and create the Lambda function

1. Run the get-login-password command to authenticate the Docker CLI to your Amazon ECR registry.

   • Set the --region value to the AWS Region where you want to create the Amazon ECR repository.

   • Replace 111122223333 with your AWS account ID.

   aws ecr get-login-password --region us-east-1 | docker login --username AWS --password-stdin 111122223333.dkr.ecr.us-east-1.amazonaws.com

2. Create a repository in Amazon ECR using the create-repository command.

   aws ecr create-repository --repository-name hello-world --region us-east-1 --image-scanning-configuration scanOnPush=true --image-tag-mutability MUTABLE

   Note

   The Amazon ECR repository must be in the same AWS Region as the Lambda function.

   If successful, you see a response like this:

   {
       "repository": {
           "repositoryArn": "arn:aws:ecr:us-east-1:111122223333:repository/hello-world",
           "registryId": "111122223333",
           "repositoryName": "hello-world",
           "repositoryUri": "111122223333.dkr.ecr.us-east-1.amazonaws.com/hello-world",
           "createdAt": "2023-03-09T10:39:01+00:00",
           "imageTagMutability": "MUTABLE",
           "imageScanningConfiguration": {
               "scanOnPush": true
           },
           "encryptionConfiguration": {
               "encryptionType": "AES256"
           }
       }
   }

3. Copy the repositoryUri from the output in the previous step.

4. Run the docker tag command to tag your local image into your Amazon ECR repository as the latest version. In this command:

   • docker-image:test is the name and tag of your Docker image. This is the image name and tag that you specified in the docker build command.

   • Replace <ECRrepositoryUri> with the repositoryUri that you copied. Make sure to include :latest at the end of the URI.

   docker tag docker-image:test <ECRrepositoryUri>:latest

   Example:

   docker tag docker-image:test 111122223333.dkr.ecr.us-east-1.amazonaws.com/hello-world:latest

5. Run the docker push command to deploy your local image to the Amazon ECR repository. Make sure to include :latest at the end of the repository URI.

   docker push 111122223333.dkr.ecr.us-east-1.amazonaws.com/hello-world:latest

6. Create an execution role for the function, if you don't already have one. You need the Amazon Resource Name (ARN) of the role in the next step.

7. Create the Lambda function. For ImageUri, specify the repository URI from earlier. Make sure to include :latest at the end of the URI.

   aws lambda create-function \
     --function-name hello-world \
     --package-type Image \
     --code ImageUri=111122223333.dkr.ecr.us-east-1.amazonaws.com/hello-world:latest \
     --role arn:aws:iam::111122223333:role/lambda-ex

   Note

   You can create a function using an image in a different AWS account, as long as the image is in the same Region as the Lambda function. For more information, see Amazon ECR cross-account permissions.

8. Invoke the function.

   aws lambda invoke --function-name hello-world response.json

   You should see a response like this:

   {
     "ExecutedVersion": "$LATEST", 
     "StatusCode": 200
   }

9. To see the output of the function, check the response.json file.

To update the function code, you must build the image again, upload the new image to the Amazon ECR repository, and then use the update-function-code command to deploy the image to the Lambda function.

Lambda resolves the image tag to a specific image digest. This means that if you point the image tag that was used to deploy the function to a new image in Amazon ECR, Lambda doesn't automatically update the function to use the new image.

To deploy the new image to the same Lambda function, you must use the update-function-code command, even if the image tag in Amazon ECR remains the same. In the following example, the --publish option creates a new version of the function using the updated container image.

aws lambda update-function-code \
  --function-name hello-world \
  --image-uri 111122223333.dkr.ecr.us-east-1.amazonaws.com/hello-world:latest \
  --publish