Support ExternalDNS integration by DNSEndpoint

[solmonk]

What type of PR is this?

feature

Which issue does this PR fix:

#88

What does this PR do / Why do we need it:

Resolves #88 by using DNSEndpoint CRD supported by ExternalDNS

If an issue # is not available please add repro steps and logs from aws-gateway-controller showing the issue:

Testing done on this change:

make e2etest and manual traffic tests

HTTPRoute resource with hostname will create the resource resembles the following. Note the ownerReferences field.

apiVersion: externaldns.k8s.io/v1alpha1
kind: DNSEndpoint
metadata:
  creationTimestamp: "2023-07-10T23:35:29Z"
  generation: 1
  name: byoc-parking-dns
  namespace: default
  ownerReferences:
  - apiVersion: gateway.networking.k8s.io/v1beta1
    blockOwnerDeletion: true
    controller: true
    kind: HTTPRoute
    name: byoc-parking
    uid: 4f494890-8314-4a37-b787-99fe80cedd0a
  resourceVersion: "17044921"
  uid: ea7f0852-9060-4927-9d89-b5f4477acdfe
spec:
  endpoints:
  - dnsName: parking.my-test.com
    recordTTL: 300
    recordType: CNAME
    targets:
    - byoc-parking-default-03f7a7580d37de850.7d67968.vpc-lattice-svcs.us-west-2.on.aws

Automation added to e2e:

Will this PR introduce any new dependencies?:

Will this break upgrades or downgrades. Has updating a running cluster been tested?:

Does this PR introduce any user-facing change?:

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[coveralls]

Pull Request Test Coverage Report for Build 5523240624

• 10 of 14 (71.43%) changed or added relevant lines in 2 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-2.8%) to 29.886%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
pkg/deploy/stack_deployer.go	1	2	50.0%
pkg/deploy/lattice/service_synthesizer.go	9	12	75.0%

Totals
Change from base Build 5511205616:	-2.8%
Covered Lines:	2933
Relevant Lines:	9814

---

💛 - Coveralls

[liwenwu-amazon]

are you planning to add e2e test for this as part of this PR? Thanks

[liwenwu-amazon]

QQ, for customer who do NOT run external DNS, will they able to use lattice controller at all?

[liwenwu-amazon]

I think we should not require customer to "MUST" run external DNS. The lattice controller should still run if they choose to manually add DNS record today or use another way to update their DNS.

[solmonk]

Running ExternalDNS is not required at all (and should not be). I have a couple of setups in this PR for it:

• Watch for DNSEndpoint will be disabled when CRD is not detected - see controller setup
• DNSEndpoint creation does not happen when CRD is not detected. This is done by detecting NoMatchError on listing DNSEndpoint resource.
• The documentation mentions that customers can setup DNS manually when not using ExternalDNS
• I have done the testing with deleting DNSEndpoint CRD

[liwenwu-amazon]

Please add some test for these business logic. thanks

[solmonk]

Will try to update a few more unit test cases. I am hoping to add e2e test case in other PR. There is a separate ongoing work on E2E testing for custom domain names so I am worried about the conflict. I can add more check when it is delivered.

[liwenwu-amazon]

Will try to update a few more unit test cases. I am hoping to add e2e test case in other PR. There is a separate ongoing work on E2E testing for custom domain names so I am worried about the conflict. I can add more check when it is delivered.

QQ, have you run e2e

• have external DNS running, but no DNS CRD?
• do not have external DNS and also no CRD?
  thanks

[solmonk]

Whether externalDNS is running or not does not matter to our controller. We could perhaps just check with CRD / no CRD scenario.

[zijun726911]

When people use ExternalDNS, do they usually create kind:DNSEndpoint by themselves, or it has some use cases that some controllers could create kind:DNSEndpoint on behalf of users?

[solmonk]

@zijun726911 Both are feasible scenarios, for automatic management I think this project is a good example.

[zijun726911]

Do we need to dos.latticeDataStore.AddLatticeService() at last, after s.dnsEndpointManager.Create() finished? i.e., if s.dnsEndpointManager.Create() failed we should not do s.latticeDataStore.AddLatticeService()?

[solmonk]

dnsEndpoint is not a requirement for a service to function so I think we can still unblock other logic that uses it. I think latticeDataStore should represent what controller actually has in Lattice.

[zijun726911]

Can you show more manual e2etest result in the PR description? for example, if you installed the CoreDNS addon in your cluster and create a httproute with hostnames it indeed can create a route53 CNAME record

QQ: I am not quite familiar with external-dns, if our k8s controller create a kind:DNSEndpoint, does external-dns be able to create corresponding privated hosted zone and associate with current cluster VPC and create corresponding CNAME record? ok, I saw ## Notes mention that, user need to manually create hosted zone

[liwenwu-amazon]

LGTM! Thank you