1package config
 2
 3import (
 4	"context"
 5	"os"
 6
 7	"github.com/aws/aws-sdk-go-v2/aws"
 8	"github.com/aws/aws-sdk-go-v2/feature/ec2/imds"
 9)
10
11const execEnvVar = "AWS_EXECUTION_ENV"
12
13// DefaultsModeOptions is the set of options that are used to configure
14type DefaultsModeOptions struct {
15	// The SDK configuration defaults mode. Defaults to legacy if not specified.
16	//
17	// Supported modes are: auto, cross-region, in-region, legacy, mobile, standard
18	Mode aws.DefaultsMode
19
20	// The EC2 Instance Metadata Client that should be used when performing environment
21	// discovery when aws.DefaultsModeAuto is set.
22	//
23	// If not specified the SDK will construct a client if the instance metadata service has not been disabled by
24	// the AWS_EC2_METADATA_DISABLED environment variable.
25	IMDSClient *imds.Client
26}
27
28func resolveDefaultsModeRuntimeEnvironment(ctx context.Context, envConfig *EnvConfig, client *imds.Client) (aws.RuntimeEnvironment, error) {
29	getRegionOutput, err := client.GetRegion(ctx, &imds.GetRegionInput{})
30	// honor context timeouts, but if we couldn't talk to IMDS don't fail runtime environment introspection.
31	select {
32	case <-ctx.Done():
33		return aws.RuntimeEnvironment{}, err
34	default:
35	}
36
37	var imdsRegion string
38	if err == nil {
39		imdsRegion = getRegionOutput.Region
40	}
41
42	return aws.RuntimeEnvironment{
43		EnvironmentIdentifier:     aws.ExecutionEnvironmentID(os.Getenv(execEnvVar)),
44		Region:                    envConfig.Region,
45		EC2InstanceMetadataRegion: imdsRegion,
46	}, nil
47}