Lifecycle-fix for target groups.

app.tf

resource "aws_lb_target_group" "app" {
  # We want a randomly generated resource name so the lifecycle block will
  # function. name_prefix can only be 6 characters due to a limitation in the
  # AWS API.
  # https://github.com/hashicorp/terraform-provider-aws/issues/636#issuecomment-637761075
  name_prefix = substr(var.environment, 0, 6)

  health_check {
    healthy_threshold   = "3"
    interval            = "30"
    matcher             = "200"
    protocol            = "HTTP"
    timeout             = "3"
    path                = "/healthcheck"
    unhealthy_threshold = "2"
  }

  port     = "80"
  protocol = "HTTP"
  vpc_id   = module.vpc.id

  target_type = "ip"

  tags = {
    Name        = "tg${var.environment}App"
    Project     = var.project
    Environment = var.environment
  }

  lifecycle {
    create_before_destroy = true
  }
}