Block build requests until environment builder is ready (#437)

* Add readiness probe
* Remove builder manager http api interface since we don’t use/need it
* Check environment builder status and block build requests until builder is ready
* Replace deprecated api extension interface
* Add healthy check to python env

buildermgr/envwatcher.go

@@ -458,6 +458,19 @@ func (envw *environmentWatcher) createBuilderDeployment(env *crd.Environment) (*
 								},
 							},
 							Command: []string{"/builder", sharedMountPath},
+							ReadinessProbe: &apiv1.Probe{
+								InitialDelaySeconds: 5,
+								PeriodSeconds:       2,
+								Handler: apiv1.Handler{
+									HTTPGet: &apiv1.HTTPGetAction{
+										Path: "/healthz",
+										Port: intstr.IntOrString{
+											Type:   intstr.Int,
+											IntVal: 8001,
+										},
+									},
+								},
+							},
 						},
 						{
 							Name:                   "fetcher",
@@ -471,6 +484,19 @@ func (envw *environmentWatcher) createBuilderDeployment(env *crd.Environment) (*
 								},
 							},
 							Command: []string{"/fetcher", sharedMountPath},
+							ReadinessProbe: &apiv1.Probe{
+								InitialDelaySeconds: 5,
+								PeriodSeconds:       2,
+								Handler: apiv1.Handler{
+									HTTPGet: &apiv1.HTTPGetAction{
+										Path: "/healthz",
+										Port: intstr.IntOrString{
+											Type:   intstr.Int,
+											IntVal: 8000,
+										},
+									},
+								},
+							},
 						},
 					},
 					ServiceAccountName: "fission-builder",