lambda running twice, and Runtime exited without providing a reason - amazon-web-services

Question

I got a lambda written in Go running on a container, the image was built with alpine-golang and run with alpine.
When testing i noticed from the logs the lambda is ran twice before exiting with the following:
Error: Runtime exited without providing a reason Runtime.ExitError
From my local system this the code runs fine without errors, i earlier tried running without a container but still faced runtime issues. The only error handling and logging mechs in my code is log.Println and fmt.Printf. Anyone got an idea of what is going on?
EDIT:
I trapped the exit code, which is turns out to be 0 but lambda exits with
Runtime exited with error: exit status 1 Runtime.ExitError

Answer 1

I really suggest going for the "without container" path. Just pack your executable into a .zip archive. Don't forget to compile with GOOS=linux for your code to be compatible with AWS Lambda.
On Linux you can use the following commands to get your archive:
GOOS=linux go build -o executableName path/to/main.go
zip archive.zip executableName
Note that you have to set Handler to be executableName in function's Runtime settings.
For handling lambda function, you have to use github.com/aws/aws-lambda-go/lambda package and in main start the handler function like lambda.Start(handler).
Full code example:
package main
import (
"context"
"log"
"github.com/aws/aws-lambda-go/lambda"
)
func main() {
lambda.Start(handler)
}
func handler(ctx context.Context) {
log.Println("successfully executed")
}

Answer 2

Make sure you are following the recommended guide lines aws provide with building the container image. https://docs.aws.amazon.com/lambda/latest/dg/go-image.html
your Dockerfile should look like this to work with lambda,
FROM public.ecr.aws/lambda/provided:al2 as build
# install compiler
RUN yum install -y golang
RUN go env -w GOPROXY=direct
# cache dependencies
ADD go.mod go.sum ./
RUN go mod download
# build
ADD . .
RUN go build -o /main
# copy artifacts to a clean image
FROM public.ecr.aws/lambda/provided:al2
COPY --from=build /main /main
ENTRYPOINT [ "/main" ]
Lambda is very strange where if you have the Dockerfile like you would on a local machine then it runs it once, ends, then a second time and crashes with no reason given