func envConfigLoad()

in aws/session/env_config.go [301:416]
89 lines of code
19 McCabe index (conditional complexity)

func envConfigLoad(enableSharedConfig bool) (envConfig, error) {
	cfg := envConfig{}

	cfg.EnableSharedConfig = enableSharedConfig

	// Static environment credentials
	var creds credentials.Value
	setFromEnvVal(&creds.AccessKeyID, credAccessEnvKey)
	setFromEnvVal(&creds.SecretAccessKey, credSecretEnvKey)
	setFromEnvVal(&creds.SessionToken, credSessionEnvKey)
	if creds.HasKeys() {
		// Require logical grouping of credentials
		creds.ProviderName = EnvProviderName
		cfg.Creds = creds
	}

	// Role Metadata
	setFromEnvVal(&cfg.RoleARN, roleARNEnvKey)
	setFromEnvVal(&cfg.RoleSessionName, roleSessionNameEnvKey)

	// Web identity environment variables
	setFromEnvVal(&cfg.WebIdentityTokenFilePath, webIdentityTokenFilePathEnvKey)

	// CSM environment variables
	setFromEnvVal(&cfg.csmEnabled, csmEnabledEnvKey)
	setFromEnvVal(&cfg.CSMHost, csmHostEnvKey)
	setFromEnvVal(&cfg.CSMPort, csmPortEnvKey)
	setFromEnvVal(&cfg.CSMClientID, csmClientIDEnvKey)

	if len(cfg.csmEnabled) != 0 {
		v, _ := strconv.ParseBool(cfg.csmEnabled)
		cfg.CSMEnabled = &v
	}

	regionKeys := regionEnvKeys
	profileKeys := profileEnvKeys
	if !cfg.EnableSharedConfig {
		regionKeys = regionKeys[:1]
		profileKeys = profileKeys[:1]
	}

	setFromEnvVal(&cfg.Region, regionKeys)
	setFromEnvVal(&cfg.Profile, profileKeys)

	// endpoint discovery is in reference to it being enabled.
	setFromEnvVal(&cfg.enableEndpointDiscovery, enableEndpointDiscoveryEnvKey)
	if len(cfg.enableEndpointDiscovery) > 0 {
		cfg.EnableEndpointDiscovery = aws.Bool(cfg.enableEndpointDiscovery != "false")
	}

	setFromEnvVal(&cfg.SharedCredentialsFile, sharedCredsFileEnvKey)
	setFromEnvVal(&cfg.SharedConfigFile, sharedConfigFileEnvKey)

	if len(cfg.SharedCredentialsFile) == 0 {
		cfg.SharedCredentialsFile = defaults.SharedCredentialsFilename()
	}
	if len(cfg.SharedConfigFile) == 0 {
		cfg.SharedConfigFile = defaults.SharedConfigFilename()
	}

	setFromEnvVal(&cfg.CustomCABundle, useCABundleKey)
	setFromEnvVal(&cfg.ClientTLSCert, useClientTLSCert)
	setFromEnvVal(&cfg.ClientTLSKey, useClientTLSKey)

	var err error
	// STS Regional Endpoint variable
	for _, k := range stsRegionalEndpointKey {
		if v := os.Getenv(k); len(v) != 0 {
			cfg.STSRegionalEndpoint, err = endpoints.GetSTSRegionalEndpoint(v)
			if err != nil {
				return cfg, fmt.Errorf("failed to load, %v from env config, %v", k, err)
			}
		}
	}

	// S3 Regional Endpoint variable
	for _, k := range s3UsEast1RegionalEndpoint {
		if v := os.Getenv(k); len(v) != 0 {
			cfg.S3UsEast1RegionalEndpoint, err = endpoints.GetS3UsEast1RegionalEndpoint(v)
			if err != nil {
				return cfg, fmt.Errorf("failed to load, %v from env config, %v", k, err)
			}
		}
	}

	var s3UseARNRegion string
	setFromEnvVal(&s3UseARNRegion, s3UseARNRegionEnvKey)
	if len(s3UseARNRegion) != 0 {
		switch {
		case strings.EqualFold(s3UseARNRegion, "false"):
			cfg.S3UseARNRegion = false
		case strings.EqualFold(s3UseARNRegion, "true"):
			cfg.S3UseARNRegion = true
		default:
			return envConfig{}, fmt.Errorf(
				"invalid value for environment variable, %s=%s, need true or false",
				s3UseARNRegionEnvKey[0], s3UseARNRegion)
		}
	}

	setFromEnvVal(&cfg.EC2IMDSEndpoint, ec2IMDSEndpointEnvKey)
	if err := setEC2IMDSEndpointMode(&cfg.EC2IMDSEndpointMode, ec2IMDSEndpointModeEnvKey); err != nil {
		return envConfig{}, err
	}
	setBoolPtrFromEnvVal(&cfg.EC2IMDSv1Disabled, ec2MetadataV1DisabledEnvKey)

	if err := setUseDualStackEndpointFromEnvVal(&cfg.UseDualStackEndpoint, awsUseDualStackEndpoint); err != nil {
		return cfg, err
	}

	if err := setUseFIPSEndpointFromEnvVal(&cfg.UseFIPSEndpoint, awsUseFIPSEndpoint); err != nil {
		return cfg, err
	}

	return cfg, nil
}