ec2id.go

//go:generate mockgen -source=$GOFILE -package=$GOPACKAGE -destination=mock_$GOFILE
package main

import (
	"context"
	"fmt"
	"os"
	"sort"

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

type EC2DescribeInstancesAPI interface {
	DescribeInstances(ctx context.Context, params *ec2.DescribeInstancesInput, optFns ...func(*ec2.Options)) (*ec2.DescribeInstancesOutput, error)
}

func GetInstances(c context.Context, api EC2DescribeInstancesAPI, input *ec2.DescribeInstancesInput) (*ec2.DescribeInstancesOutput, error) {
	return api.DescribeInstances(c, input)
}

func NewAwsClient() (EC2DescribeInstancesAPI, error) {
	cfg, err := config.LoadDefaultConfig(context.TODO())
	if err != nil {
		fmt.Fprintln(os.Stderr, "configuration error")
		return nil, err
	}
	return ec2.NewFromConfig(cfg), nil
}

func Ec2id(name string, client EC2DescribeInstancesAPI) ([]string, error) {
	result, err := GetInstances(context.TODO(), client, buildDescribeInstancesInput(name))
	if err != nil {
		fmt.Fprintln(os.Stderr, "Got an error retrieving information about your Amazon EC2 instance")
		return nil, err
	}

	if len(result.Reservations) == 0 {
		return nil, nil
	}

	var filteredInstance = []types.Instance{}
	for _, v := range result.Reservations {
		filteredInstance = append(filteredInstance, v.Instances...)
	}

	sort.Slice(filteredInstance, func(i, j int) bool {
		return filteredInstance[i].LaunchTime.After(*filteredInstance[j].LaunchTime)
	})

	var instanceIds = []string{}
	for _, v := range filteredInstance {
		instanceIds = append(instanceIds, *v.InstanceId)
	}

	return instanceIds, nil
}

func buildDescribeInstancesInput(name string) *ec2.DescribeInstancesInput {
	var filter = []types.Filter{
		{
			Name:   aws.String("instance-state-name"),
			Values: []string{"running"},
		},
	}
	if len(name) != 0 {
		filter = append(filter, types.Filter{
			Name:   aws.String("tag:Name"),
			Values: []string{name},
		})
	}

	return &ec2.DescribeInstancesInput{
		Filters: filter,
	}
}