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Deploy Go Lambda functions with .zip file archives

Your AWS Lambda function's code consists of scripts or compiled programs and their dependencies. You use a deployment package to deploy your function code to Lambda. Lambda supports two types of deployment packages: container images and .zip file archives.

This page describes how to create a .zip file as your deployment package for the Go runtime, and then use the .zip file to deploy your function code to AWS Lambda using the AWS Command Line Interface (AWS CLI).

Topics

Prerequisites

The AWS CLI is an open-source tool that enables you to interact with AWS services using commands in your command line shell. To complete the steps in this section, you must have the following:

Tools and libraries

Lambda provides the following tools and libraries for the Go runtime:

Tools and libraries for Go

For more information, see aws-lambda-go on GitHub.

Sample applications

Lambda provides the following sample applications for the Go runtime:

Sample Lambda applications in Go

  • blank-go – A Go function that shows the use of Lambda's Go libraries, logging, environment variables, and the AWS SDK.

Creating a .zip file on macOS and Linux

The following steps demonstrate how to download the lambda library from GitHub with go get, and compile your executable with go build.

  1. Download the lambda library from GitHub.

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

  2. Compile your executable.

    GOOS=linux GOARCH=amd64 go build -o main main.go

    Setting GOOS to linux ensures that the compiled executable is compatible with the Go runtime, even if you compile it in a non-Linux environment.

  3. (Optional) If your main package consists of multiple files, use the following go build command to compile the package:

    GOOS=linux GOARCH=amd64 go build main

  4. (Optional) You may need to compile packages with CGO_ENABLED=0 set on Linux:

    GOOS=linux GOARCH=amd64 CGO_ENABLED=0 go build -o main main.go

    This command creates a stable binary package for standard C library (libc) versions, which may be different on Lambda and other devices.

  5. Lambda uses POSIX file permissions, so you may need to set permissions for the deployment package folder before you create the .zip file archive.

  6. Create a deployment package by packaging the executable in a .zip file.

    zip main.zip main

Creating a .zip file on Windows

The following steps demonstrate how to download the lambda library from GitHub with go get, download the build-lambda-zip tool for Windows from GitHub with go install, and compile your executable with go build.

Note
If you have not already done so, you must install git and then add the git executable to your Windows %PATH% environment variable.

  1. Download the lambda library from GitHub.

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

  2. Download the build-lambda-zip tool from GitHub.

    go.exe install github.com/aws/aws-lambda-go/cmd/build-lambda-zip@latest

  3. Use the tool from your GOPATH to create a .zip file. If you have a default installation of Go, the tool is typically in %USERPROFILE%\Go\bin. Otherwise, navigate to where you installed the Go runtime and do one of the following:

[ cmd.exe ]

In cmd.exe, run the following:

set GOOS=linux
set GOARCH=amd64
set CGO_ENABLED=0
go build -o main main.go
%USERPROFILE%\Go\bin\build-lambda-zip.exe -o main.zip main

[ PowerShell ]

In PowerShell, run the following:

$env:GOOS = "linux"
$env:GOARCH = "amd64"
$env:CGO_ENABLED = "0"
go build -o main main.go
~\Go\Bin\build-lambda-zip.exe -o main.zip main

Creating a Lambda function using a .zip archive

In addition to the main.zip deployment package you have created, to create a Lambda function you also need an execution role. 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 can create an execution role for your function in the IAM console or using the AWS Command Line Interface (AWS CLI).

The following steps demonstrate how to create the execution role using the AWS CLI and then create a Lambda function using your .zip deployment package.

  1. Create a trust policy giving the Lambda service permission to assume the execution role. Copy the following JSON and create a file named trust-policy.json in the current directory.

    {
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Principal": {
        "Service": "lambda.amazonaws.com"
      },
      "Action": "sts:AssumeRole"
    }
  ]
}

  2. Create the execution role.

    aws iam create-role --role-name lambda-ex --assume-role-policy-document file://trust-policy.json

    You should see the following output. Make a note of your role's ARN. You will need this to create your function.

    {
    "Role": {
        "Path": "/",
        "RoleName": "lambda-ex",
        "RoleId": "AROAQFOXMPL6TZ6ITKWND",
        "Arn": "arn:aws:iam::123456789012:role/lambda-ex",
        "CreateDate": "2020-01-17T23:19:12Z",
        "AssumeRolePolicyDocument": {
            "Version": "2012-10-17",
            "Statement": [
                {
                    "Effect": "Allow",
                    "Principal": {
                        "Service": "lambda.amazonaws.com"
                    },
                    "Action": "sts:AssumeRole"
                }
            ]
        }
    }
}

  3. Add permissions to the role using the attach-role-policy command. In the example below, you add the AWSLambdaBasicExecutionRole managed policy, which allows your Lambda function to upload logs to CloudWatch. If your Lambda function interacts with other AWS services, such as Amazon S3 or DynamoDB, you will need to add policies allowing your Lambda function to access these services. See AWS managed policies for Lambda features for more information.

    aws iam attach-role-policy --role-name lambda-ex --policy-arn arn:aws:iam::aws:policy/service-role/AWSLambdaBasicExecutionRole

  4. Create the function.

    aws lambda create-function --function-name my-function --runtime go1.x --role arn:aws:iam::123456789012:role/lambda-ex --handler main --zip-file fileb://main.zip

Note
When you create a Go Lambda function using the AWS CLI, the value of the handler setting you define is the executable file name. For more information, see AWS Lambda function handler in Go.

Build Go with the provided.al2 runtime

Go is implemented differently than other native runtimes. Lambda treats Go as a custom runtime, so you can create a Go function on the provided.al2 runtime. You can use the AWS SAM build command to build the .zip file package.

Using AWS SAM to build Go for AL2 function

  1. Update the AWS SAM template to use the provided.al2 runtime. Also set the BuildMethod to makefile.

    Resources:
  HelloWorldFunction:
    Type: AWS::Serverless::Function
    Properties:
      CodeUri: hello-world/
      Handler: my.bootstrap.file
      Runtime: provided.al2
      Architectures: [arm64]  
    Metadata:
      BuildMethod: makefile

    Remove the Architectures property to build the package for the x86_64 instruction set architecture.

  2. Add file makefile to the project folder, with the following contents:

    GOOS=linux go build -o bootstrap
	cp ./bootstrap $(ARTIFACTS_DIR)/.

For an example application, download Go on AL2. The readme file contains the instructions to build and run the application. You can also view the blog post Migrating AWS Lambda functions to Amazon Linux 2.