Using vars in kustomize

kustomize-vars-demo.sh

#!/usr/bin/env bash

set -eu
set -o pipefail

TMPDIR="$(mktemp -d)"
pushd $TMPDIR 2>&1 >/dev/null

[ -d "app" ] || mkdir app kustomizeconfig

cat <<_EOF_ >app/domain-cm.yml
---
apiVersion: v1
kind: ConfigMap
metadata:
  labels:
    app.kubernetes.io/name: domain-cm
    app.kubernetes.io/part-of: argocd
  name: domain-cm
  namespace: monitoring
data:
  domain: dev-eks.acme.com
_EOF_


cat <<_EOF_ > app/kustomization.yml
---
resources:
- deployment.yml
- ingress.yml
- domain-cm.yml
_EOF_

cat <<_EOF_ > app/deployment.yml
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: my-app
  labels:
    app: my-app
spec:
  replicas: 1
  template:
    spec:
      containers:
      - name: my-app
        image: my-app
        ports:
        - containerPort: 808
_EOF_

cat <<'_EOF_' > app/ingress.yml
---
apiVersion: extensions/v1beta1
kind: Ingress
metadata:
  name: my-app
spec:
  tls:
    - hosts:
        - foo.bar.com
      secretName: tls-secret5
  rules:
    - host: foo.bar.com
      http:
        paths:
          - backend:
              serviceName: $(APP_SERVICE)
              domainName: $(APP_DOMAIN)
              servicePort: 8080
---
kind: Service
apiVersion: v1
metadata:
  name: my-app-service
  annotations:
    external-dns.alpha.kubernetes.io/hostname: my-app.$(APP_DOMAIN)
spec:
  type: LoadBalancer
  ports:
  - port: 8080
    name: http
  - port: 8181
    name: http-ssl
  selector:
    app: my-app
_EOF_

cat <<_EOF_ > kustomizeconfig/config.yml
---
varReference:
- path: spec/rules/http/paths/backend/serviceName
  kind: Ingress
- path: spec/rules/http/paths/backend/domainName
  kind: Ingress
- path: metadata/annotations
  kind: Service  
_EOF_

cat <<_EOF_ > kustomization.yml
---
apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization
commonLabels:
  app: my-app

imageTags:
  - name: my-app
    newName: localhost/my-app
    newTag: latest

bases:
- app

namePrefix: dev-

vars:
  - name: APP_SERVICE
    objref:
      kind: Service
      name: my-app-service
      apiVersion: v1
    fieldref:
      fieldpath: metadata.name
  - name: APP_DOMAIN
    objref:
      kind: ConfigMap
      name: domain-cm
      apiVersion: v1
    fieldref:
      fieldpath: data.domain
configurations:
- kustomizeconfig/config.yml
_EOF_

tree
kustomize build .

popd  2>&1 >/dev/null
rm -fr "${TMPDIR}"