test-env-pod.json

{
  "kind":"Pod",
  "apiVersion":"v1",
  "metadata":{
    "name":"test-pod",
    "labels":{
      "name":"test-pod"
    }
  },
  "spec":{
    "containers":[
      {
        "name":"test",
        "image":"centos:centos7",
        "env": [
          {
            "name":"podname",
            "valueFrom": {
              "fieldRef": {
                "fieldPath":"metadata.name"
              }
            }
          },
          {
            "name":"podname_composed",
            "value":"$(podname)_composed"
          },
          {
            "name":"var1",
            "value":"value1"
          },
          {
            "name":"var2",
            "value":"$(var1)"
          },
          {
            "name":"var3",
            "value":"120"
          }
        ],
        "command": [
          "sleep",
          "$(var3)"
        ]
      }
    ],
    "restartPolicy":"Never",
    "dnsPolicy":"ClusterFirst"
  }
}