add profile feature in maya types (openebs-archive#134)

* introduce k8s based storage class utility file
* fix a minor doc issue while implementing openebs/openebs#717

1. Why is this change necessary ?

This is a part of bigger scheme of things. It will
enable part implementation of openebs/openebs#693
openebs/openebs#694 and openebs/openebs#409

This particular implementation fixes openebs/openebs#717

2. How does this change address the issue ?

- Adds a k8s_storage_class.go file

- Adds a few labels, keys & utility functions
w.r.t storage class

3. How to verify this change ?

- make should work fine

- The actual verfication will be part of
bigger changes mentioned in above issues.

4. What side effects does this change have ?

- None

- Unit test should be implemented as mentioned in
openebs/openebs#725

types/profiles/v1/doc.go

@@ -0,0 +1,23 @@
+/*
+Copyright 2017 The OpenEBS Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+// Profiles are related to OpenEBS volume.
+// Profiles can be categorized into volume related placements, volume
+// related provisioning, and probably a few more features in the future.
+// Profiles are meant to be used by storage admins to communicate
+// their volume requirements to Maya without being involved into providing
+// exact values or numbers.
+package v1

types/profiles/v1/profiles.go

@@ -0,0 +1,119 @@
+/*
+Copyright 2017 The OpenEBS Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+// This file deals with the labels, constants, defaults & utility
+// functions related to the profiles
+package v1
+
+import (
+	"fmt"
+	"strings"
+)
+
+// ProvisionPolicyKey type deals with the keys associated with
+// volume provisioning. It is expected that these keys will have
+// corresponding values.
+//
+// USAGE:
+//  When OpenEBS storage is managed with Kubernetes (K8s) as the underlying
+// container orchestrator, then provision policy key can be used as following:
+//
+// apiVersion: storage.k8s.io/v1
+// kind: StorageClass
+// metadata:
+//    name: openebs-jupyter
+//    labels:
+//     provision/replica-count: 2
+//     provision/controller-count: 1
+// provisioner: openebs.io/provisioner-iscsi
+// parameters:
+//   pool: hostdir-var
+//   replica: "2"
+//   size: 5G
+type ProvisionPolicyKey string
+
+const (
+	ReplicaCountPPK         ProvisionPolicyKey = "provision/replica-count"
+	ControllerCountPPK      ProvisionPolicyKey = "provision/controller-count"
+	ReplicaTolerationPPK    ProvisionPolicyKey = "provision/replica-toleration"
+	ControllerTolerationPPK ProvisionPolicyKey = "provision/controller-toleration"
+)
+
+// PlacementPolicyKey is a constant which will be used as a key. This key can be
+// associated with one or more placement policies as value(s).
+//
+// USAGE:
+//  When OpenEBS storage is managed with Kubernetes (K8s) as the underlying
+// container orchestrator; then placement policy key can be used as following:
+//
+// apiVersion: storage.k8s.io/v1
+// kind: StorageClass
+// metadata:
+//    name: openebs-jupyter
+//    labels:
+//     placement: "spread-replica, sticky-replica"
+//     provision/replica-count: 2
+// provisioner: openebs.io/provisioner-iscsi
+// parameters:
+//   pool: hostdir-var
+//   replica: "2"
+//   size: 5G
+const (
+	PlacementPolicyKey string = "placement"
+)
+
+// PlacementPolicyValue type deals with various volume placement related
+// policy value(s). These can be thought of as flags. Presence of these policy
+// flags indicate enabling of corresponding placement.
+//
+// NOTE to developer:
+//  Care should be exercised to filter/prioritize policies if some of them
+// are conflicting. Particular examples will be mentioned when the developer
+// have them.
+//
+// USAGE:
+//  Already mentioned in PlacementPolicyKey
+type PlacementPolicyValue string
+
+const (
+	SpreadReplicaPPV PlacementPolicyValue = "spread-replica"
+	StickyReplicaPPV PlacementPolicyValue = "sticky-replica"
+)
+
+// IsStickyReplica indicates if sticking replicas to their placement
+// Nodes is mentioned in provided policies.
+func IsStickyReplica(policies map[string]string) (bool, error) {
+	// TODO logic
+	return false, fmt.Errorf("Not implemented")
+}
+
+// IsSpreadReplica indicates if spreading the replicas across Nodes
+// is mentioned in provided policies.
+func IsSpreadReplica(policies map[string]string) (bool, error) {
+	// TODO logic
+	return false, fmt.Errorf("Not implemented")
+}
+
+// GetReplicaCount gets the value of replica count if available
+func GetReplicaCount(policies map[string]string) (string, bool) {
+	for k, v := range policies {
+		if strings.TrimSpace(k) == string(ReplicaCountPPK) {
+			return strings.TrimSpace(v), true
+		}
+	}
+
+	return "", false
+}