Use this data source to get IDs and VPC membership of Security Groups that are created outside of Terraform.
data "aws_security_groups" "test" {
  tags {
    Application = "k8s",
    Environment = "dev"
  }
}
data "aws_security_groups" "test" {
  filter {
    name   = "group-name"
    values = ["*nodes*"]
  }
  filter {
    name   = "vpc-id"
    values = ["${var.vpc_id}"]
  }
}
tags - (Optional) A mapping of tags, each pair of which must exactly match for desired security groups.
filter - (Optional) One or more name/value pairs to use as filters. There are several valid keys, for a full reference, check out describe-security-groups in the AWS CLI reference.
ids - IDs of the matches security groups. vpc_ids - The VPC IDs of the matched security groups. The data source's tag or filter will span VPCs unless the vpc-id filter is also used. 
    © 2018 HashiCorpLicensed under the MPL 2.0 License.
    https://www.terraform.io/docs/providers/aws/d/security_groups.html