foo.yaml

apiVersion: v1
kind: ConfigMap
metadata:
  name: server
  namespace: foo
data:
  server.go: |
    package main
    import (
        "fmt"
        "net/http"
        "os"
    )
    func main() {
        http.HandleFunc("/foo", func(writer http.ResponseWriter, request *http.Request) {
            fmt.Fprintln(writer, "foo", os.Getenv("POD_NAME"))
        })
        http.ListenAndServe(":8000", nil)
    }
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: foo
  namespace: foo
spec:
  selector:
    matchLabels:
      app: foo
  template:
    metadata:
      name: foo
      labels:
        app: foo
    spec:
      volumes:
        - name: server
          configMap:
            name: server
      containers:
        - name: foo
          image: golang
          ports:
            - name: http
              containerPort: 8000
          volumeMounts:
            - name: server
              mountPath: /app
          command: [go, run, /app/server.go]
          env:
            - name: POD_NAME
              valueFrom:
                fieldRef:
                  fieldPath: metadata.name
---
apiVersion: v1
kind: Service
metadata:
  name: foo
  namespace: foo
spec:
  selector:
    app: foo
  ports:
    - port: 80
      targetPort: http