contour argo ingress.yaml

apiVersion: extensions/v1beta1
kind: Ingress
metadata:
  name: argocd-server-http-ingress
  namespace: argocd
  annotations:
    kubernetes.io/ingress.class: "contour"
    ingress.kubernetes.io/force-ssl-redirect: "true"
spec:
  rules:
  - http:
      paths:
      - backend:
          serviceName: argocd-server
          servicePort: http
    host: argocd.example.com
  tls:
  - hosts:
    - argocd.example.com
    secretName: argocd-secret # do not change, this is provided by Argo CD
---
apiVersion: extensions/v1beta1
kind: Ingress
metadata:
    name: argocd-server-grpc-ingress
    namespace: argocd
    annotations:
    kubernetes.io/ingress.class: "contour"
spec:
    rules:
    - http:
        paths:
        - backend:
            serviceName: argocd-server
            servicePort: https
    host: grpc.argocd.example.com
    tls:
    - hosts:
    - grpc.argocd.example.com
    secretName: argocd-secret # do not change, this is provided by Argo CD
---
apiVersion: v1
kind: Service
metadata:
    annotations:
      projectcontour.io/upstream-protocol.h2c: "https,443"
    labels:
    app.kubernetes.io/component: server
    app.kubernetes.io/instance: argocd
    app.kubernetes.io/managed-by: pulumi
    app.kubernetes.io/name: argocd-server
    app.kubernetes.io/part-of: argocd
    helm.sh/chart: argo-cd-2.7.0
    name: argocd-server
    namespace: infra
spec:
    ports:
    - name: http
    port: 80
    protocol: TCP
    targetPort: server
    - name: https
    port: 443
    protocol: TCP
    targetPort: server
    selector:
    app.kubernetes.io/instance: argocd
    app.kubernetes.io/name: argocd-server
    sessionAffinity: None
    type: ClusterIP

Here is a Patch if you want to patch the Annotation on the default argocd manifest:

apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization
resources:
  - https://github.com/argoproj/argo-cd/raw/v2.7.5/manifests/install.yaml
patches:
  # adds service annotation for grpc
  - target:
      kind: Service
      name: argocd-server
    patch: |-
      - op: add
        path: /metadata/annotations
        value:
          projectcontour.io/upstream-protocol.h2c: https,443