Add cluster backup + restore functionality

Adds cluster backup (JSON dump) and restore functions for use in
disaster recovery.

Further, adds additional confirmation to the initialization (as well as
restore) endpoints to avoid accidental triggering, and also groups the
init, backup, and restore commands in the CLI into a new "task"
subsection.

api-daemon/pvcapid/flaskapi.py

@@ -333,14 +333,23 @@ api.add_resource(API_Logout, '/logout')
 
 # /initialize
 class API_Initialize(Resource):
+    @RequestParser([
+        {'name': 'yes-i-really-mean-it', 'required': True, 'helptext': "Initialization is destructive; please confirm with the argument 'yes-i-really-mean-it'."}
+    ])
     @Authenticator
-    def post(self):
+    def post(self, reqargs):
         """
         Initialize a new PVC cluster
         Note: Normally used only once during cluster bootstrap; checks for the existence of the "/primary_node" key before proceeding and returns 400 if found
         ---
         tags:
           - root
+        parameters:
+          - in: query
+            name: yes-i-really-mean-it
+            type: string
+            required: true
+            description: A confirmation string to ensure that the API consumer really means it
         responses:
           200:
             description: OK
@@ -363,6 +372,82 @@ class API_Initialize(Resource):
 api.add_resource(API_Initialize, '/initialize')
 
 
+# /backup
+class API_Backup(Resource):
+    @Authenticator
+    def get(self):
+        """
+        Back up the Zookeeper data of a cluster in JSON format
+        ---
+        tags:
+          - root
+        responses:
+          200:
+            description: OK
+            schema:
+              type: object
+              id: Cluster Data
+          400:
+            description: Bad request
+        """
+        return api_helper.backup_cluster()
+
+
+api.add_resource(API_Backup, '/backup')
+
+
+# /restore
+class API_Restore(Resource):
+    @RequestParser([
+        {'name': 'yes-i-really-mean-it', 'required': True, 'helptext': "Restore is destructive; please confirm with the argument 'yes-i-really-mean-it'."},
+        {'name': 'cluster_data', 'required': True, 'helptext': "A cluster JSON backup must be provided."}
+    ])
+    @Authenticator
+    def post(self, reqargs):
+        """
+        Restore a backup over the cluster; destroys the existing data
+        ---
+        tags:
+          - root
+        parameters:
+          - in: query
+            name: yes-i-really-mean-it
+            type: string
+            required: true
+            description: A confirmation string to ensure that the API consumer really means it
+          - in: query
+            name: cluster_data
+            type: string
+            required: true
+            description: The raw JSON cluster backup data
+        responses:
+          200:
+            description: OK
+            schema:
+              type: object
+              id: Message
+          400:
+            description: Bad request
+            schema:
+              type: object
+              id: Message
+          500:
+            description: Restore error or code failure
+            schema:
+              type: object
+              id: Message
+        """
+        try:
+            cluster_data = reqargs.get('cluster_data')
+        except Exception as e:
+            return {"message": "Failed to load JSON backup: {}.".format(e)}, 400
+
+        return api_helper.restore_cluster(cluster_data)
+
+
+api.add_resource(API_Restore, '/restore')
+
+
 # /status
 class API_Status(Resource):
     @Authenticator