Lambda retrieve SSM parameter in Localstack - amazon-web-services

Question

Using the latest localstack-full Docker image, I have stored an encrypted SSM parameter like this:
aws --region us-east-1 --endpoint-url=http://localhost:4566 ssm put-parameter --name "dbpassword" --value "secret2" --type "SecureString"
Then I have implemented a lambda in Go that I can access via API gateway. The implementation looks like this:
package main
import (
"context"
"github.com/aws/aws-lambda-go/events"
"github.com/aws/aws-lambda-go/lambda"
"github.com/aws/aws-sdk-go-v2/aws"
"github.com/aws/aws-sdk-go-v2/config"
"github.com/aws/aws-sdk-go-v2/service/ssm"
"log"
"os"
)
type Event struct {
Name string `json:"name"`
}
func HandleRequest(ctx context.Context, event Event) (events.APIGatewayProxyResponse, error) {
theAwsRegion := os.Getenv("AWS_REGION")
//customResolver := aws.EndpointResolverFunc(func(service, region string) (aws.Endpoint, error) {
// return aws.Endpoint{
// PartitionID: "aws",
// URL: "localhost:4566",
// SigningRegion: "us-east-1",
// }, nil
//})
theConfig, err := config.LoadDefaultConfig(
ctx,
config.WithRegion(theAwsRegion),
//config.WithEndpointResolver(customResolver),
)
if err != nil {
log.Fatalf("Unable to load SDK config, %v", err)
}
ssmClient := ssm.NewFromConfig(theConfig)
if ssmClient != nil {
ssmOutput, err := ssmClient.GetParameter(ctx, &ssm.GetParameterInput{Name: aws.String("dbpassword"), WithDecryption: true})
if err != nil {
return events.APIGatewayProxyResponse{
StatusCode: 200,
Headers: map[string]string{"Context-Type": "text/plain"},
Body: "Error occurred getting password",
IsBase64Encoded: false,
}, nil
}
thePassword := ssmOutput.Parameter.Value
return events.APIGatewayProxyResponse{
StatusCode: 200,
Headers: map[string]string{"Context-Type": "text/plain"},
Body: "Got a SSM client " + *thePassword,
IsBase64Encoded: false,
}, nil
}
return events.APIGatewayProxyResponse{
StatusCode: 200,
Headers: map[string]string{"Context-Type": "text/plain"},
Body: "Failed to obtain SSM client",
IsBase64Encoded: false,
}, nil
}
func main() {
lambda.Start(HandleRequest)
}
However, the lambda only responds with "{}" as soon as the call to GetParameter is introduced.
An SSM client is successfully retrieved.
There is also code commented-out attempt to use a custom endpoint resolver, which produces the same result.
Is there a problem with Localstack or what am I doing wrong?
Retrieving the parameter using the AWS CLI works without problems.
Update: I have tried to access the Localstack container from the lambda container over port 4566 and were able to obtain a response from the Localstack container.