Configuring a Lambda Function to Receive Notifications

The following example configures the Lambda function functionName to accept notifications from the resource with the ARN sourceArn.

Import the packages we use.

import (
    "flag"
    "fmt"
    "os"

    "github.com/aws/aws-sdk-go/aws"
    "github.com/aws/aws-sdk-go/aws/session"
    "github.com/aws/aws-sdk-go/service/lambda"
)

Get the name of the function and ARN of the entity invoking the function. If either is missing, print an error message and quit.

functionPtr := flag.String("f", "", "The name of the Lambda function")
sourcePtr := flag.String("a", "", "The ARN of the entity invoking the function")
flag.Parse()

if *functionPtr == "" || *sourcePtr == "" {
    fmt.Println("You must supply the name of the function and of the entity invoking the function")
    flag.PrintDefaults()
    os.Exit(1)
}

Create the session and Lambda client.

sess := session.Must(session.NewSessionWithOptions(session.Options{
    SharedConfigState: session.SharedConfigEnable,
}))

svc := lambda.New(sess)

Create the structure for the input argument to the AddPermission function.

permArgs := &lambda.AddPermissionInput{
    Action:       aws.String("lambda:InvokeFunction"),
    FunctionName: functionPtr,
    Principal:    aws.String("s3.amazonaws.com"),
    SourceArn:    sourcePtr,
    StatementId:  aws.String("lambda_s3_notification"),
}

Finally, call AddPermission and display a message with the result of the call.

result, err := svc.AddPermission(permArgs)
if err != nil {
    fmt.Println("Cannot configure function for notifications")
    os.Exit(0)
}

fmt.Println(result)

See the complete example on GitHub.