Add metadata annotations to generated apex objects

[jonnylangefeld]

Some third party software relies on annotations and labels on istios VirtualServices. For instance external-dns makes use of the external-dns.alpha.kubernetes.io/controller annotation. Currently there is no way to set labels and annotations on the VirtualService resource.

This change takes the metadata from the canary.Spec.Service.Apex property to replicate exactly what is already possible for a traefik resource:

flagger/pkg/router/traefik.go

Lines 59 to 68 in c36a13c

	tsMetadata := canary.Spec.Service.Apex
	if tsMetadata == nil {
	tsMetadata = &flaggerv1.CustomMetadata{}
	}
	if tsMetadata.Labels == nil {
	tsMetadata.Labels = make(map[string]string)
	}
	if tsMetadata.Annotations == nil {
	tsMetadata.Annotations = make(map[string]string)
	}

Fix #854

Signed-off-by: Jonny Langefeld jonny.langefeld@gmail.com

[stefanprodan]

LGTM

Thanks @jonnylangefeld 🏅

[codecov-commenter]

Codecov Report

Merging #1034 (d5994ac) into main (01d4780) will increase coverage by 0.26%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main    #1034      +/-   ##
==========================================
+ Coverage   56.88%   57.15%   +0.26%     
==========================================
  Files          76       76              
  Lines        6093     6138      +45     
==========================================
+ Hits         3466     3508      +42     
- Misses       2102     2103       +1     
- Partials      525      527       +2     

Impacted Files	Coverage Δ
pkg/router/appmesh.go	85.42% <100.00%> (+0.45%)	⬆️
pkg/router/appmesh_v1beta2.go	88.12% <100.00%> (+0.30%)	⬆️
pkg/router/contour.go	88.54% <100.00%> (+0.36%)	⬆️
pkg/router/gloo.go	75.79% <100.00%> (+1.03%)	⬆️
pkg/router/istio.go	81.07% <100.00%> (-0.48%)	⬇️

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[MaesterZ]

If I am not mistaken this will add annotations to both the Kubernetes services and Istio virtualservices, not sure what happens with external-dns.alpha.kubernetes.io/target in this case especially if you want the annotation only on one of them (the service or the virtual service).

Also this new feature/behavior should be mentioned in the docs?

[stefanprodan]

@Misteur-Z my understanding is that external-dns doesn't look at VirtualServices by default, you need to enable it with --source=istio-virtualservice and doing so, Kubernetes services are ignored.

[stefanprodan]

Also this new feature/behavior should be mentioned in the docs?

Thanks! I've added a note to docs here 6f65907

[MaesterZ]

@Misteur-Z my understanding is that external-dns doesn't look at VirtualServices by default, you need to enable it with --source=istio-virtualservice and doing so, Kubernetes services are ignored.

It's fine if you only use the virtual service source for External DNS, but you could also enable multiple ones (service + ingress + virtualservice), there is no limitations.
https://github.com/kubernetes-sigs/external-dns/blob/master/docs/tutorials/istio.md

[stefanprodan]

@Misteur-Z could you please make a PR and add a warning on external-dns? Thanks for raising this, I think users should be made aware that enabling both Istio and Service sources would result in conflicts.

[jonnylangefeld]

An alternative would be to create a new field on the canary to propagate metadata just to a specific apex (like only VirtualServiec or only Service). But that obviously would overload the canary object quite a bit