Drop focal support - #8843

🤖 AI-generated review. Authored by an AI agent. Findings were validated locally as described below; suggested changes were compiled and tested before posting.

Assessment

Correct and self-consistent. No blocking issues found.

The removed families are unreachable in practice: eksctl's minimum supported EKS version is now 1.31, while 20.04 SSM resolution was bounded to >= 1.21, < 1.29. Confirmed against AWS SSM in us-west-2 — no /aws/service/canonical/ubuntu/eks{,-pro}/20.04/<version>/… parameter exists for any supported version. The auto-resolver fallback matches nothing either, since no ubuntu-eks/k8s_1.31/images/*20.04-* images are published.

Other checks that came back clean: schema.json regenerates with no diff; the deleted integration/tests/custom_ami/testdata/ubuntu-pro-2004.yaml was already orphaned on main (no test read it); no stale Ubuntu2004/UbuntuPro2004/20.04/focal references remain outside historical release notes; the Ubuntu2404/Ubuntu2604 resolution paths are separate switch cases and are untouched.

This also fixes two pre-existing copy/paste errors in gpu_validation_test.go, where the entries labelled Ubuntu2204 and UbuntuPro2204 both asserted against NodeImageFamilyUbuntu2004.

Non-blocking: two test entries deleted rather than retargeted

Both cover behaviour that still applies to 22.04, so the lost coverage looks incidental.

1. pkg/apis/eksctl.io/v1alpha5/gpu_validation_test.go — the GPU-drivers-warning DescribeTable is now Windows-only. The entry mislabelled "Windows without GPU instances" (it actually used Ubuntu2004) was the only coverage of the explicit-zero branch in validation.go:

if ng.InstanceSelector != nil && !ng.InstanceSelector.IsZero() &&
    (ng.InstanceSelector.GPUs == nil || *ng.InstanceSelector.GPUs != 0) {

GPUs: newInt(0) now appears nowhere in the repository, leaving that guard untested. The enclosing condition still excludes only AL2, AL2023 and Bottlerocket, so Ubuntu remains in scope.

Suggested, inserted before Entry("Windows with explicit GPU instance", …):

		Entry("Ubuntu without GPU instances", gpuInstanceEntry{
			amiFamily: api.NodeImageFamilyUbuntu2204,
			instanceSelector: &api.InstanceSelector{
				VCPUs: 4,
				GPUs:  newInt(0),
			},
		}),
		Entry("Ubuntu with implicit GPU instance", gpuInstanceEntry{
			amiFamily: api.NodeImageFamilyUbuntu2204,
			instanceSelector: &api.InstanceSelector{
				VCPUs: 4,
				GPUs:  newInt(2),
			},
			expectWarning: true,
		}),

2. integration/tests/managed/managed_nodegroup_test.go — the Managed CLI features table no longer has any Ubuntu entry. Retargeting rather than removing:

		Entry("Ubuntu with dry-run", managedCLIEntry{
			createArgs: []string{
				"--node-ami-family=Ubuntu2204",
				"--dry-run",
			},
		}),

Both suggestions were applied locally and verified: gofmt clean, go vet -tags integration clean, and pkg/apis/eksctl.io/v1alpha5 runs 545 of 545 specs green with both restored entries executing.

Out of scope for this PR

validateVersionForUbuntu bounds Ubuntu2204/UbuntuPro2204 at >= 1.29 with no upper bound, but published images stop earlier:

Ubuntu 22.04 (eks):  1.29 1.30 1.31 1.32
Ubuntu 24.04 (eks):  1.31 1.32 1.33 1.34 1.35 1.36

--node-ami-family=Ubuntu2204 on EKS 1.33+ therefore passes validation and then fails at resolution with a wrapped SDK error. Pre-existing, and the same failure mode this PR removes for 20.04 — noted only because 22.04 is where this change redirects users. Not a request against this PR.