Show links in UI for non-core ingress resources

[maxnitze]

Summary

It should be possible for ArgoCD to display links for non-core ingress resources.

Motivation

Besides the Kubernetes-core resource Ingress, some applications come with CRDs, that define new ingress resources. OpenShift Route (https://docs.openshift.com/container-platform/4.11/rest_api/network_apis/route-route-openshift-io-v1.html) and Traefik IngressRoute (https://doc.traefik.io/traefik/providers/kubernetes-crd/) come to my mind. For OpenShift there is a (seems-to-be-abandoned) open PR #5096.

Proposal

Links could be implemented the same way health checks are: Resource Customization.

Bundle Popular Resources with ArgoCD

Bundle more popular resources with ArgoCD natively, like we do it for health checks for some resources.

For example Prometheus:

argo-cd/resource_customizations/monitoring.coreos.com/Prometheus/health.lua

Lines 1 to 23 in 231fab4

	hs={ status = "Progressing", message = "Waiting for initialization" }
	if obj.status ~= nil then
	if obj.status.conditions ~= nil then
	for i, condition in ipairs(obj.status.conditions) do
	if condition.type == "Available" and condition.status ~= "True" then
	if condition.reason == "SomePodsNotReady" then
	hs.status = "Progressing"
	else
	hs.status = "Degraded"
	end
	hs.message = condition.message or condition.reason
	end
	if condition.type == "Available" and condition.status == "True" then
	hs.status = "Healthy"
	hs.message = "All instances are available"
	end
	end
	end
	end
	return hs

We could put a links.lua in the same folder for links created for Prometheus resources, for example.

Read Link Customization from ArgoCD config

Provide a way to specify resource customization in the argocd-cm.yaml file.

For example health checks for custom resources:

argo-cd/docs/operator-manual/argocd-cm.yaml

Lines 104 to 124 in 231fab4

	resource.customizations.health.certmanager.k8s.io-Certificate: |
	hs = {}
	if obj.status ~= nil then
	if obj.status.conditions ~= nil then
	for i, condition in ipairs(obj.status.conditions) do
	if condition.type == "Ready" and condition.status == "False" then
	hs.status = "Degraded"
	hs.message = condition.message
	return hs
	end
	if condition.type == "Ready" and condition.status == "True" then
	hs.status = "Healthy"
	hs.message = condition.message
	return hs
	end
	end
	end
	end
	hs.status = "Progressing"
	hs.message = "Waiting for certificate"
	return hs

Example for Traefik IngressRoute:

data:
  ...
  resource.customizations.links.traefik.containo.us-IngressRoute |
    links = []
    // walk object and create link for each configured host and path
    return links

Additional Requirements

• It should be possible to create multiple links from one resource, as one IngressRoute can define multiple ingress rules.
• Links should propagate up to the Application resource, like they do for core Ingress resources.
• This might also be affected by ArgoCD UI Ingress go-to links use wrong URL scheme (HTTP) #8021

Releated Issues

• Deep-links to logging facility etc #4281
• Make Argo UI aware of OpenShift objects, such as Route and DeploymentConfig #4601
• Add support for arbitrary links in app dashboard #3487