• *Description of problem:*

The ingress controller is trying to add all subnets included in the VPC to the default router when installing OCP in existing VPC[1] which has subnets in Local Zones[1] (which does not support networking load balancers[3], only application ones/ALB).

The ingress cluster operator is reporting the following error when installing the cluster:

~~~
ingress False True True 92s The "default" ingress controller reports Available=False: IngressControllerUnavailable: One or more status conditions indicate unavailable: LoadBalancerReady=False (SyncLoadBalancerFailed: The service-controller component is reporting SyncLoadBalancerFailed events like: Error syncing load balancer: failed to ensure load balancer: ValidationError: You cannot have any Local Zone subnets for load balancers of type 'classic'...
~~~

I managed to workaround it by tagging `kubernetes.io/cluster/unmanaged=true` on the Local Zone subnet so that the ingress controller will ignore that subnet. The name `unmanaged` must be anything different than the `InfraID`. When the tag key suffix is the `InfraID`, regardless the value, it still failing.

There is work in progress to create the official support (product documentation+QE in progress) of Local Zones installing in existing VPCs[4], then implement the fully support in installer[5][6]. The current issue seems to be a blocker for the full implementation, as the installer tag the subnets with cluster tag[1] `kubernetes.io/cluster/<infraID>=.*`.

• *OpenShift release version:*

All versions (tested in 4.10.18, 4.11.0-fc.0, 4.11.0-rc.1)

• *How reproducible:*

Always

• *Steps to Reproduce (in detail):*

1. Create the VPC
2. Create the Local Zone subnet, setting the tag `kubernetes.io/cluster/unmanaged=true`
3. Create the Installer configuration setting the subnets in the "availability-zone" (parent zone)
4. Create the manifests
5. Create the Machine Sets for the machines located on the Local Zone subnet
6. Create the cluster

• *Actual results:*

Installer failed due to the ingress operator (and dependencies) reports degraded (message above from cluster operators)

• *Expected results:*

The ingress (OR):

• Should not auto discovery all the subnets in the VPC when the subnets has been set on the install-config.yaml;
• Should not auto discovery all the subnets in the VPC when the `kubernetes.io/role/elb=1` has been added to public subnets;
• Should not try to add subnets not supported (Local Zones, Wavelength) to the technology used by Load Balancer (CLB/NLB) on the ingress[7];
• Auto discover could ignore the tag `kubernetes.io/role/elb=0` when it's set on the public subnet, so we can specify what subnets we would not like to be added/used by Load Balancer;

• *Impact of the problem:*

• Installations are not finished when trying to use existig VPCs with subnets in Local Zones (without workaround)
• Block the fully support of Local Zones/Wavelenght on Installer since the cluster tag must be set on the subnet: `kubernetes.io/cluster/<infraID>=.*`

• *Additional info:*

[1] Install in existing VPC:
https://docs.openshift.com/container-platform/4.10/installing/installing_aws/installing-aws-vpc.html

[2] Local Zone documentation:
https://aws.amazon.com/about-aws/global-infrastructure/localzones/

[3] Local Zones limitations (LB):
https://aws.amazon.com/about-aws/global-infrastructure/localzones/features/

[4] Research and Day-0 support documentation to install OCP in existing VPC with Local Zones subnets:
https://issues.redhat.com/browse/SPLAT-635

[5] Epic to create Machine pools in Local Zones in existing VPC with Local Zones subnets:
https://issues.redhat.com/browse/SPLAT-636

[6] Epic to implement full support on installer to create subnets in Local Zones:
https://issues.redhat.com/browse/SPLAT-657

[7] The SDK provides the field indicating the type of the subnet, since the network load balancers (CLB/NLB) the controller should look into the field `ZoneType` and add only subnets on the zone type value `availability-zone`, or ignore zones `wavelength-zone` and `local-zone`.
~~~
$ aws ec2 describe-availability-zones --filters Name=region-name,Values=us-east-1 --all-availability-zones |jq -r '.AvailabilityZones[] | ( .ZoneName, .ZoneType)'
us-east-1a
availability-zone
(...)
us-east-1-bos-1a
local-zone
(...)
us-east-1-wl1-atl-wlz-1
wavelength-zone
(...)
~~~