tierType, exists := config.isTierNameInUse(tierName)
	if !exists {
		return errTierNotFound
	}

	cfg := config.Tiers[tierName]
	switch tierType {
	case madmin.S3:
		if creds.AWSRole {
			cfg.S3.AWSRole = true
		}
		if creds.AWSRoleWebIdentityTokenFile != "" && creds.AWSRoleARN != "" {
			cfg.S3.AWSRoleARN = creds.AWSRoleARN
			cfg.S3.AWSRoleWebIdentityTokenFile = creds.AWSRoleWebIdentityTokenFile
		}