Chunking a slice for an AWS API Call

chunking.go

package main

import (
	"context"

	"github.com/aws/aws-sdk-go-v2/service/ec2"
	ec2types "github.com/aws/aws-sdk-go-v2/service/ec2/types"
)

func DescribeAllInstances(instanceIDs []string, ec2Client *ec2.Client) ([]ec2types.Instance, error) {
	result := make([]ec2types.Instance, 0)
	chunkSize := 10
	for i := 0; i <= len(instanceIDs); i += chunkSize {
		end := i + chunkSize
		if end > len(instanceIDs) {
			end = len(instanceIDs)
		}
		if resp, err := ec2Client.DescribeInstances(context.TODO(), &ec2.DescribeInstancesInput{
			InstanceIds: instanceIDs[i:end],
		}); err != nil {
			return result, err
		} else {
			for _, res := range resp.Reservations {
				result = append(result, res.Instances...)
			}
		}
	}
	return result, nil
}