added blue green strategy (#47)

* added blue green strategy

* Addressed review comments

* addressed pr comments

* updated names in test

* addressed final pr comments

src/utilities/strategy-helpers/service-blue-green-helper.ts

@@ -0,0 +1,102 @@
+'use strict';
+
+import { Kubectl } from '../../kubectl-object-model';
+import * as fileHelper from '../files-helper';
+import { createWorkloadsWithLabel, getManifestObjects, addBlueGreenLabelsAndAnnotations, fetchResource, deleteWorkloadsWithLabel, cleanUp, isServiceRouted } from './blue-green-helper';
+import { GREEN_LABEL_VALUE, NONE_LABEL_VALUE, BLUE_GREEN_VERSION_LABEL } from './blue-green-helper';
+
+export function deployBlueGreenService(kubectl: Kubectl, filePaths: string[]) {
+    // get all kubernetes objects defined in manifest files
+    const manifestObjects = getManifestObjects(filePaths);
+
+    // create deployments with green label value
+    const result = createWorkloadsWithLabel(kubectl, manifestObjects.deploymentEntityList, GREEN_LABEL_VALUE);
+
+    // create other non deployment and non service entities
+    const newObjectsList = manifestObjects.otherObjects.concat(manifestObjects.ingressEntityList);
+    const manifestFiles = fileHelper.writeObjectsToFile(newObjectsList);
+    kubectl.apply(manifestFiles);
+    
+    // returning deployment details to check for rollout stability
+    return result;
+}
+
+export async function promoteBlueGreenService(kubectl: Kubectl, manifestObjects) {
+    // checking if services are in the right state ie. targeting green deployments
+    if (!validateServicesState(kubectl, manifestObjects.deploymentEntityList, manifestObjects.serviceEntityList)) {
+        throw('NotInPromoteState');
+    }
+
+    // creating stable deployments with new configurations
+    const result = createWorkloadsWithLabel(kubectl, manifestObjects.deploymentEntityList, NONE_LABEL_VALUE);
+    
+    // returning deployment details to check for rollout stability
+    return result;
+}
+
+export async function rejectBlueGreenService(kubectl: Kubectl, filePaths: string[]) {
+    // get all kubernetes objects defined in manifest files
+    const manifestObjects = getManifestObjects(filePaths);
+
+    // routing to stable objects
+    routeBlueGreenService(kubectl, NONE_LABEL_VALUE, manifestObjects.deploymentEntityList, manifestObjects.serviceEntityList);
+
+    // seeing if we should even delete the service
+    cleanUp(kubectl, manifestObjects.deploymentEntityList, manifestObjects.serviceEntityList);
+    
+    // deleting the new deployments with green suffix
+    deleteWorkloadsWithLabel(kubectl, GREEN_LABEL_VALUE, manifestObjects.deploymentEntityList);
+}
+
+export function routeBlueGreenService(kubectl: Kubectl, nextLabel: string, deploymentEntityList: any[], serviceEntityList: any[]) {
+    const newObjectsList = [];
+    serviceEntityList.forEach((serviceObject) => {
+        if (isServiceRouted(serviceObject, deploymentEntityList)) {
+            // if service is routed, point it to given label
+            const newBlueGreenServiceObject = getUpdatedBlueGreenService(serviceObject, nextLabel);
+            newObjectsList.push(newBlueGreenServiceObject);
+        } else {
+            // if service is not routed, just push the original service
+            newObjectsList.push(serviceObject);
+        }
+    });
+    // configures the services
+    const manifestFiles = fileHelper.writeObjectsToFile(newObjectsList);
+    kubectl.apply(manifestFiles);
+}
+
+// adding green labels to configure existing service
+function getUpdatedBlueGreenService(inputObject: any, labelValue: string): object {
+    const newObject = JSON.parse(JSON.stringify(inputObject));
+    // Adding labels and annotations.
+    addBlueGreenLabelsAndAnnotations(newObject, labelValue);
+    return newObject;
+}
+
+export function validateServicesState(kubectl: Kubectl, deploymentEntityList: any[], serviceEntityList: any[]): boolean {
+    let areServicesGreen: boolean = true;
+    serviceEntityList.forEach((serviceObject) => {
+        if (isServiceRouted(serviceObject, deploymentEntityList)) {
+            // finding the existing routed service
+            const existingService = fetchResource(kubectl, serviceObject.kind, serviceObject.metadata.name);
+            if (!!existingService) {
+                let currentLabel: string = getServiceSpecLabel(existingService);
+                if(currentLabel != GREEN_LABEL_VALUE) {
+                    // service should be targeting deployments with green label
+                    areServicesGreen = false;
+                }
+            } else {
+                // service targeting deployment doesn't exist
+                areServicesGreen = false;
+            }
+        }
+    });
+    return areServicesGreen;
+}
+
+export function getServiceSpecLabel(inputObject: any): string {
+    if(!!inputObject && inputObject.spec && inputObject.spec.selector && inputObject.spec.selector[BLUE_GREEN_VERSION_LABEL]) {
+        return inputObject.spec.selector[BLUE_GREEN_VERSION_LABEL]; 
+    }
+    return '';
+}