Minor refactorings (#368)

* Split vkubelet funcitons into separate files.

* Minor re-org for cmd/census*

* refactor run loop

vkubelet/env.go

@@ -0,0 +1,63 @@
+package vkubelet
+
+import (
+	"fmt"
+
+	corev1 "k8s.io/api/core/v1"
+	"k8s.io/apimachinery/pkg/api/errors"
+)
+
+// populateEnvironmentVariables populates Secrets and ConfigMap into environment variables
+func (s *Server) populateEnvironmentVariables(pod *corev1.Pod) error {
+	for _, c := range pod.Spec.Containers {
+		for i, e := range c.Env {
+			if e.ValueFrom != nil {
+				// Populate ConfigMaps to Env
+				if e.ValueFrom.ConfigMapKeyRef != nil {
+					vf := e.ValueFrom.ConfigMapKeyRef
+					cm, err := s.resourceManager.GetConfigMap(vf.Name, pod.Namespace)
+					if vf.Optional != nil && !*vf.Optional && errors.IsNotFound(err) {
+						return fmt.Errorf("ConfigMap %s is required by Pod %s and does not exist", vf.Name, pod.Name)
+					}
+
+					if err != nil {
+						return fmt.Errorf("Error retrieving ConfigMap %s required by Pod %s: %s", vf.Name, pod.Name, err)
+					}
+
+					var ok bool
+					if c.Env[i].Value, ok = cm.Data[vf.Key]; !ok {
+						return fmt.Errorf("ConfigMap %s key %s is required by Pod %s and does not exist", vf.Name, vf.Key, pod.Name)
+					}
+					continue
+				}
+
+				// Populate Secrets to Env
+				if e.ValueFrom.SecretKeyRef != nil {
+					vf := e.ValueFrom.SecretKeyRef
+					sec, err := s.resourceManager.GetSecret(vf.Name, pod.Namespace)
+					if vf.Optional != nil && !*vf.Optional && errors.IsNotFound(err) {
+						return fmt.Errorf("Secret %s is required by Pod %s and does not exist", vf.Name, pod.Name)
+					}
+					v, ok := sec.Data[vf.Key]
+					if !ok {
+						return fmt.Errorf("Secret %s key %s is required by Pod %s and does not exist", vf.Name, vf.Key, pod.Name)
+					}
+					c.Env[i].Value = string(v)
+					continue
+				}
+
+				// TODO: Populate Downward API to Env
+				if e.ValueFrom.FieldRef != nil {
+					continue
+				}
+
+				// TODO: Populate resource requests
+				if e.ValueFrom.ResourceFieldRef != nil {
+					continue
+				}
+			}
+		}
+	}
+
+	return nil
+}