ytt double-quoted strings

deployment.yaml

#@ load("@ytt:data", "data")
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: one
  labels:
    app: web
spec:
  replicas: 2
  selector:
    matchLabels:
      app: web
  template:
    metadata:
      labels:
        app: web
    spec:
      containers:
        - name: front-end
          image: nginx
          ports:
            - containerPort: 80
          resources:
            requests:
              cpu: 500m
              memory: 500Mi
          env:
            - name: FRONTEND_TAGS
              value: #@ data.values.frontendTags

values.yaml

#@data/values
---
frontendTags: "hey,hello"