Creating an AWS Lambda Function in Go and Troubleshooting Common Errors
Tags: lambda, go, development, troubleshooting
Published: 2023-09-06 00:39:44

**Introduction**

AWS Lambda is a powerful service that allows you to run your code without provisioning or managing servers. In this tutorial, we will walk through the process of creating an AWS Lambda function using the Go programming language (we are going to code a Lambda function in the next one). We'll also address a common error that you might encounter during this setup and provide solutions to resolve it.

**Prerequisites**

Before you begin, ensure you have the following:

- An AWS account.
- AWS CLI installed and configured: You can log in to your AWS account and configure the AWS CLI by running the following command in your terminal:

`aws configure`

This command will prompt you to enter your AWS Access Key ID, Secret Access Key, default region name, and output format.  These credentials can be obtained from your AWS account settings under _IAM > Users > Security credentials_.
- Go programming language installed.

**Step 1: Setting up Go Modules**

If you're working with Go, it's a good practice to use Go modules to manage your dependencies. Even for a single-file project, Go modules help maintain consistency and allow for future expansion.

- In your project directory, initialize Go modules with your chosen module name:
`go mod init DynamoDBCreateTable`

- Install any necessary dependencies using go get, if applicable.

**Step 2: Building Your Lambda Function**

Now, let's create your Lambda function using Go:

- Write your Lambda function code in a Go file (e.g., [DynamoDBCreateTable.go](https://dev.to/aws-builders/use-go-lambda-and-api-gateway-to-generate-dynamodb-tables-on-demand-kj2)).

- Build your Go code for the Lambda environment:
`GOOS=linux GOARCH=arm64 CGO_ENABLED=0 go build -o bootstrap -tags lambda.norpc DynamoDBCreateTable.go`

_Note: The resulting binary is named "bootstrap" because AWS Lambda expects this name for Go functions (read more [here](https://docs.aws.amazon.com/lambda/latest/dg/golang-package.html#golang-package-mac-linux)). In many other programming languages, the handler for an AWS Lambda function is typically named as a method or function within your code. However, in Go, it should be specifically named "bootstrap"._

Once you've created the AWS Lambda function with the correct handler name, you can proceed with the next step.

**Step 3: Zip Your Go File**

Before deploying your AWS Lambda function, you'll need to package your Go code into a zip file. In your terminal, navigate to the directory containing your Go code file, which in our case is "bootstrap." Run the following command to create a zip file:

`zip DynamoDBCreateTable.zip bootstrap`

This command will package your Go code into a zip file named "DynamoDBCreateTable.zip."

**Step 4: Create the Lambda Function**

- Deploy your Lambda function using the AWS CLI:

```
aws lambda create-function \
--function-name CreateDBTable \
--runtime provided.al2 \
--handler bootstrap \
--architectures arm64 \
--role arn:aws:iam::11112222333:role/service-role/DynamoDBCreateTable**** \
--zip-file fileb://DynamoDBCreateTable.zip
```
--function-name: Specify a name for your Lambda function.
--runtime: Set the runtime to "provided.al2" for Go (recommended).
--handler: Set the handler to "bootstrap" to match the Go entry point.
--architectures: Specify the architecture as needed.
--role: Provide the ARN of the IAM role with necessary permissions.

**Troubleshooting: Handling Common Errors**

If you encounter the error message "fork/exec /var/task/bootstrap: no such file or directory: PathError," follow these steps:

1. Ensure that your Go code is correctly built for the Lambda environment.
2. Verify that the handler in your aws lambda create-function command is set to "bootstrap".
3. Double-check the IAM role's permissions to ensure it has access to the required AWS services.

**Conclusion**

Building Lambda functions with Go is a powerful way to run serverless code while making deployment easy. Just follow these steps and watch out for common mistakes. Now you've got the skills to launch your own Lambda functions using AWS CLI and leverage AWS's serverless platform.

Feel free to customize your code to connect with DynamoDB or other AWS services your app needs.

Stay Tuned: In our next post, we'll dive deeper into Lambda functions. We'll walk through creating one that dynamically generates DynamoDB tables by calling an API Gateway. This will expand your serverless skills so you can build scalable, efficient apps on AWS.

Keep coding and stay motivated!