glambda

Glambda Deployment Tool

Glambda is a simple tool for bundling and deploying AL2023 compatible Lambda functions written in Go. It provides an easy way to create, update and delete AWS Lambdas quickly from the command line using a compact set of commands.

Get started with Glambda by running the following command:

glambda deploy <lambdaName> <path/to/handler.go> 

The intent is to maximise ease of use, at the expense of infinite customisability, and doesn't really play in the same space as SAM, CDK or Terraform.

If you'd prefer to use these more mature tools, consider using the package sub-command which will just write out a well formatted zip file ready to upload to AWS.

Why though?

AWS pivoted from a Go managed runtime to an OS only runtime. I'd argue that relative to the managed runtime, the OS only runtime has a much higher barrier to entry. Hence this libary!

You can learn more about it at https://docs.aws.amazon.com/lambda/latest/dg/lambda-golang.html

Prerequisites

To use Glambda, you will need an AWS account, and an AWS Access Key ID and Secret Access Key with the appropriate permissions to create and manage Lambda functions, as well as IAM roles.

Glambda will also assume the following AWS environment variables are set up:

export AWS_ACCESS_KEY_ID=<your-access-key-id>
export AWS_SECRET_ACCESS_KEY=<your-secret-access-key>
export AWS_DEFAULT_REGION=<your-region>

Installation

To install Glambda, run:

go install github.com/mr-joshcrane/glambda/cmd/glambda@latest

Usage

Package a lambda, ready for deployment

If you've already got a deployment tool you'd prefer to use, no problem. You can build the lambda zip file with the package sub-command.

## Default output path is "./bootstrap" which is what AWS will be expecting
glambda deploy package <path/to/handler.go>
## Alternatively you can provide the output path explicitly
glambda deploy package <path/to/handler.go> --output /my/custom/filepath/artifact.zip

From here you'll have the ability to take this zip file and do what needs doing in your tool of choice.

Create new lambdas directly

Run the following command to deploy a Lambda function with an associated execution role:

glambda deploy <lambdaName> <path/to/handler.go> 

Replace <lambdaName> with the desired name for your Lambda function and <path/to/handler.go> with the path to your Lambda function's handler file.

The source file should have a main function that calls lambda.Start(handler). See https://pkg.go.dev/github.com/aws/aws-lambda-go/lambda#Start for more details.

Update existing lambdas

What's that? You've updated your code and need to deploy a new version of your Lambda function? No problem! Just run the same command as before, and Glambda will update the function code for you without recreating the lambda or the role.

In fact, assuming the path to your handler didnt change, we only need to run the same command!

glambda deploy <lambdaName> <path/to/handler.go>

Execution Role and Lambda Resource Permissions

OK, that's nice, but sometimes your role actually has to DO things. Like access S3 buckets or DynamoDB tables. No problem! Glambda can attach managed policies, inline policies, and resource policies to your Lambda function's execution role.

## Attach a managed policy by name or ARN to the Lambda function's execution roles
managedPolicies=S3FullAccess,arn:aws:iam::aws:policy/AmazonDynamoDBFullAccess

## Attach an inline policy (as a JSON literal) to the Lambda function's execution roles
inlinePolicies='{"Effect": "Deny", "Action": "s3:GetObject", "Resource": "*"}'

## Attach a resource policy (as a JSON literal) to the Lambda function
resourcePolicies='{
            "Sid": "YourLambdaResourcePolicy",
            "Effect": "Allow",
            "Principal": {
              "Service": "events.amazonaws.com"
            },
            "Action": "lambda:InvokeFunction",
            "Resource":  "arn:aws:lambda:us-east-2:123456789012:function:my-function",
            "Condition": {
              "StringEquals": {
                "AWS:SourceAccount": "123456789012"
              }
        }'

glambda deploy <lambdaName> <path/to/handler.go> \
    --managed-policies ${managedPolicies} \
    --inline-policy ${inlinePolicies} \
    --resource-policy ${resourcePolicies}

Deleting lambdas and associated roles

Deleting your Lambda function and associated role is also easy, performed with the following command:

glambda delete <lambdaName>