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Using a Custom Runtime for Go-Based Lambda Functions

Despite Go having native support in AWS Lambda, switching to a custom runtime has its advantages

man running across patio

Lambda runtimes: native vs custom

The native runtime for Go

package mainimport (
type Event struct {
Name string `json:"name"`
func main() {
h := func HandleRequest(ctx context.Context, e Event) (string, error) {
return fmt.Sprintf("Invoked by: %s", e.Name ), nil

Three advantages to using a custom runtime for Go

1. Support for Lambda Extensions

2. Provides an Amazon Linux 2 execution environment

3. Unifies the runtime and handler code

Migrating from the Go native runtime to a custom runtime

Change #1 — Build bootstrap binary

GOOS=linux go build -o ./bootstrap ./...

Change #2 — Remove RPC for faster cold-start

GOOS=linux go build -o ./bootstrap ./... -tags lambda.norpc

Change #3 — Update Lambda configuration

Type: AWS::Serverless::Function
Handler: bootstrap
Runtime: provided.al2
... # Other required properties

Putting it all together



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Travis Bale

Software Engineer at Capital One and AWS enthusiast who loves deep-diving into all things DevOps, Serverless, and Security