Kustomize how to replace only the host in Ingress configuration

You can use a json patch for this, below is an example.

Here is an example kustomization.yaml. It will call out a patch in the patches section:

apiVersion: kustomize.config.k8s.io/v1beta1kind: Kustomizationresources:- ../../base/app1patches:- target:    kind: Ingress    name: my-ingress  path: ingress-patch.json  

Here would be an example ingress-patch.json:

[    {         "op": "replace",         "path": "/spec/rules/0/host",         "value": "the.real.hostname"    }]

If you are on a recent version of kubernetes (I think starting form 18) the Ingres api version is no longer the beta one apiVersion: extensions/v1beta1 it is now apiVersion: networking.k8s.io/v1.

I have tested bellow sample and it works :

ingress.yaml

apiVersion: networking.k8s.io/v1kind: Ingressmetadata:  name: asap-ingress-internal  annotations:    kubernetes.io/ingress.class: "nginx-external"    nginx.ingress.kubernetes.io/use-regex: "true"spec:  rules:    - host: the-host-value      http:        paths:          - path: /asap-srv-template/(.*)            backend:              serviceName: asap-srv-template              servicePort: 8080

ingress-patch.yaml

apiVersion: networking.k8s.io/v1kind: Ingressmetadata:  name: asap-ingress-internalspec:  rules:    - host: the.real.hostname

kustomization.yaml

resources:- ingress.yamlpatchesStrategicMerge:- ingress-patch.yaml

Tested with both kubectl kustomize (version of kubectl is v1.19.7) and kustomize build (version of standalone kustomize is v3.5.4 )