This blueprint bootstraps a minimal infrastructure for testing [ILB as next hop](https://cloud.google.com/load-balancing/docs/internal/ilb-next-hop-overview), using simple Linux gateway VMS between two VPCs to emulate virtual appliances.
Two ILBs are configured on the primary and secondary interfaces of gateway VMs with active health checks, but only a single one is used as next hop by default to simplify testing. The second (right-side) VPC has default routes that point to the gateway VMs, to also use the right-side ILB as next hop set the `ilb_right_enable` variable to `true`.
This setup can be used to test and verify new Internal Network LB features like [forwards all protocols on Internal Network LB as next hops](https://cloud.google.com/load-balancing/docs/internal/ilb-next-hop-overview#all-traffic) and [symmetric hashing](https://cloud.google.com/load-balancing/docs/internal/ilb-next-hop-overview#symmetric-hashing), using simple `curl` and `ping` tests on clients. To make this practical, test VMs on both VPCs have `nginx` pre-installed and active on port 80.
Session affinity on the Internal Network LB backend services can be changed using `gcloud compute backend-services update` on each of the Internal Network LBs, or by setting the `ilb_session_affinity` variable to update both Internal Network LBs.
Simple `/root/start.sh` and `/root/stop.sh` scripts are pre-installed on both gateways to configure `iptables` so that health check requests are rejected and re-enabled, to quickly simulate removing instances from the Internal Network LB backends.
Basic commands to SSH to VMs and monitor backend health are provided in the Terraform outputs, and they already match input variables so that names, zones, etc. are correct. Other testing commands are provided below, adjust names to match your setup.
| [ip_ranges](variables.tf#L29) | IP CIDR ranges used for VPC subnets. | <code>map(string)</code> | | <codetitle="{ left = "10.0.0.0/24" right = "10.0.1.0/24" }">{…}</code> |
| [project_create](variables.tf#L47) | Create project instead of using an existing one. | <code>bool</code> | | <code>false</code> |
| [region](variables.tf#L58) | Region used for resources. | <code>string</code> | | <code>"europe-west1"</code> |
| [zones](variables.tf#L64) | Zone suffixes used for instances. | <code>list(string)</code> | | <code>["b", "c"]</code> |