Improve error handling of getting the hosted zone nameservers

[trepel]

If private hosted zone is used (it is not supported at the moment but it does not matter) the operator panics when trying to access nameservers. The private hosted zones do not have them. Improve the error handling so that operator does not crash and proper message is shown in logs.

This issue was observed for v0.1.0 tag, the affected code:

dns-operator/internal/provider/aws/aws.go

Line 167 in 515b614

managedZoneOutput.NameServers = getResp.DelegationSet.NameServers

Note that the private hosted zone can look like this:

aws route53 get-hosted-zone --id=Z01234567T8N9RVU0NABC
{
    "HostedZone": {
        "Id": "/hostedzone/Z01234567T8N9RVU0NABC",
        "Name": "abc.def.com.",
        "CallerReference": "terraform-20240319062238790500000003",
        "Config": {
            "Comment": "Dev Managed Zone",
            "PrivateZone": true
        },
        "ResourceRecordSetCount": 5
    },
    "VPCs": [
        {
            "VPCRegion": "us-east-1",
            "VPCId": "vpc-0f11d467dd89ac123"
        }
    ]
}

In particular there is no DelegationSet nor NameServers there as it would for public zone, e.g.:

...
    "DelegationSet": {
        "NameServers": [
            "ns-645.awsdns-16.net",
            "ns-1157.awsdns-16.org",
            "ns-1743.awsdns-25.co.uk",
            "ns-496.awsdns-62.com"
        ]
    }
}

The error in policy-controller pod logs looks like:

2024-03-19T09:35:47Z	ERROR	Reconciler error	{"controller": "dnsrecord", "controllerGroup": "kuadrant.io", "controllerKind": "DNSRecord", "DNSRecord": {"name":"api-gateway-api","namespace":"kuadrant-system"}, "namespace": "kuadrant-system", "name": "api-gateway-api", "reconcileID": "2902bc51-4e90-4c78-a066-6183305db74c", "error": "the managed zone is not in a ready state : trepel01-dev-mz"}
sigs.k8s.io/controller-runtime/pkg/internal/controller.(*Controller).reconcileHandler
	/go/pkg/mod/sigs.k8s.io/[email protected]/pkg/internal/controller/controller.go:329
sigs.k8s.io/controller-runtime/pkg/internal/controller.(*Controller).processNextWorkItem
	/go/pkg/mod/sigs.k8s.io/[email protected]/pkg/internal/controller/controller.go:266
sigs.k8s.io/controller-runtime/pkg/internal/controller.(*Controller).Start.func2.2
	/go/pkg/mod/sigs.k8s.io/[email protected]/pkg/internal/controller/controller.go:227
2024-03-19T09:35:47Z	DEBUG	Route53 provider created	{"managed zone:": "trepel01-dev-mz"}
2024-03-19T09:35:47Z	INFO	Observed a panic in reconciler: runtime error: invalid memory address or nil pointer dereference	{"controller": "managedzone", "controllerGroup": "kuadrant.io", "controllerKind": "ManagedZone", "ManagedZone": {"name":"trepel01-dev-mz","namespace":"kuadrant-system"}, "namespace": "kuadrant-system", "name": "trepel01-dev-mz", "reconcileID": "9fbc8c78-931b-476b-a153-3c9c5dd4d0a8"}
panic: runtime error: invalid memory address or nil pointer dereference [recovered]
	panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x10 pc=0x17fe3d3]

goroutine 169 [running]:
sigs.k8s.io/controller-runtime/pkg/internal/controller.(*Controller).Reconcile.func1()
	/go/pkg/mod/sigs.k8s.io/[email protected]/pkg/internal/controller/controller.go:116 +0x1e5
panic({0x1b71f00?, 0x33173a0?})
	/usr/local/go/src/runtime/panic.go:914 +0x21f
github.com/Kuadrant/multicluster-gateway-controller/pkg/dns/aws.(*Route53DNSProvider).EnsureManagedZone(0xc0019b83c0, 0xc0001b9ba0)
	/workspace/pkg/dns/aws/dns.go:131 +0x353
github.com/Kuadrant/multicluster-gateway-controller/pkg/controllers/managedzone.(*ManagedZoneReconciler).publishManagedZone(0x2381670?, {0x237f1a8?, 0xc0008a03c0?}, 0xc0001b9ba0)
	/workspace/pkg/controllers/managedzone/managedzone_controller.go:170 +0x5a
github.com/Kuadrant/multicluster-gateway-controller/pkg/controllers/managedzone.(*ManagedZoneReconciler).Reconcile(0xc000809b00, {0x237f1a8, 0xc0008a03c0}, {{{0xc0004dd350?, 0x5?}, {0xc0004dd370?, 0xc000897d48?}}})
	/workspace/pkg/controllers/managedzone/managedzone_controller.go:107 +0x695
sigs.k8s.io/controller-runtime/pkg/internal/controller.(*Controller).Reconcile(0x2382088?, {0x237f1a8?, 0xc0008a03c0?}, {{{0xc0004dd350?, 0xb?}, {0xc0004dd370?, 0x0?}}})
	/go/pkg/mod/sigs.k8s.io/[email protected]/pkg/internal/controller/controller.go:119 +0xb7
sigs.k8s.io/controller-runtime/pkg/internal/controller.(*Controller).reconcileHandler(0xc00080cdc0, {0x237f1e0, 0xc0005800a0}, {0x1c27a80?, 0xc000588460?})
	/go/pkg/mod/sigs.k8s.io/[email protected]/pkg/internal/controller/controller.go:316 +0x3cc
sigs.k8s.io/controller-runtime/pkg/internal/controller.(*Controller).processNextWorkItem(0xc00080cdc0, {0x237f1e0, 0xc0005800a0})
	/go/pkg/mod/sigs.k8s.io/[email protected]/pkg/internal/controller/controller.go:266 +0x1c9
sigs.k8s.io/controller-runtime/pkg/internal/controller.(*Controller).Start.func2.2()
	/go/pkg/mod/sigs.k8s.io/[email protected]/pkg/internal/controller/controller.go:227 +0x79
created by sigs.k8s.io/controller-runtime/pkg/internal/controller.(*Controller).Start.func2 in goroutine 120
	/go/pkg/mod/sigs.k8s.io/[email protected]/pkg/internal/controller/controller.go:223 +0x565

This issue was created upon request in this slack thread:
https://kubernetes.slack.com/archives/C05J0D0V525/p1710844895665569

[maleck13]

possible fix #65