feat(analytics): adding google analytics for ZFSPV

Whenever a volume is provisioned and de-provisioned we will send a google event with mainly following details :
1.    pvName (will shown as app title in google analytics)
2.    size of the volume
3.    event type : volume-provision, volume-deprovision
4.    storage type zfs-localpv
5.    replicacount as 1
6.    ClientId as default namespace uuid

Apart from this, we send the event once in 24 hr, which will have some info like number of nodes, node type, kubernetes version etc.

This metric is cotrolled by OPENEBS_IO_ENABLE_ANALYTICS env. We can set it to false if we don't want to send the metrics.

Signed-off-by: Pawan <pawan@mayadata.io>

pkg/client/k8s/v1alpha1/config.go

@@ -0,0 +1,99 @@
+/*
+Copyright 2020 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.
+*/
+
+package v1alpha1
+
+import (
+	"github.com/openebs/zfs-localpv/pkg/common/env"
+	"github.com/pkg/errors"
+	"k8s.io/client-go/rest"
+	"k8s.io/client-go/tools/clientcmd"
+	"strings"
+)
+
+// ConfigGetter abstracts fetching of kubernetes client config
+type ConfigGetter interface {
+	Get() (*rest.Config, error)
+	Name() string
+}
+
+// configFromENV is an implementation of ConfigGetter
+type configFromENV struct{}
+
+// Name returns the name of this config getter instance
+func (c *configFromENV) Name() string {
+	return "k8s-config-from-env"
+}
+
+// Get returns kubernetes rest config based on kubernetes environment values
+func (c *configFromENV) Get() (*rest.Config, error) {
+	k8sMaster := env.Get(env.KubeMaster)
+	kubeConfig := env.Get(env.KubeConfig)
+
+	if len(strings.TrimSpace(k8sMaster)) == 0 && len(strings.TrimSpace(kubeConfig)) == 0 {
+		return nil, errors.New("missing kubernetes master as well as kubeconfig: failed to get kubernetes client config")
+	}
+
+	return clientcmd.BuildConfigFromFlags(k8sMaster, kubeConfig)
+}
+
+// configFromREST is an implementation of ConfigGetter
+type configFromREST struct{}
+
+// Name returns the name of this config getter instance
+func (c *configFromREST) Name() string {
+	return "k8s-config-from-rest"
+}
+
+// Get returns kubernetes rest config based on in-cluster config implementation
+func (c *configFromREST) Get() (*rest.Config, error) {
+	return rest.InClusterConfig()
+}
+
+// ConfigGetters holds a list of ConfigGetter instances
+//
+// NOTE:
+//  This is an implementation of ConfigGetter
+type ConfigGetters []ConfigGetter
+
+// Name returns the name of this config getter instance
+func (c ConfigGetters) Name() string {
+	return "list-of-k8s-config-getter"
+}
+
+// Get fetches the kubernetes client config that is used to make kubernetes API
+// calls. It makes use of its list of getter instances to fetch kubernetes
+// config.
+func (c ConfigGetters) Get() (config *rest.Config, err error) {
+	var errs []error
+	for _, g := range c {
+		config, err = g.Get()
+		if err == nil {
+			return
+		}
+		errs = append(errs, errors.Wrapf(err, "failed to get kubernetes client config via %s", g.Name()))
+	}
+	// at this point; all getters have failed
+	err = errors.Errorf("%+v", errs)
+	err = errors.Wrap(err, "failed to get kubernetes client config")
+	return
+}
+
+// Config provides appropriate config getter instances that help in fetching
+// kubernetes client config to invoke kubernetes API calls
+func Config() ConfigGetter {
+	return ConfigGetters{&configFromENV{}, &configFromREST{}}
+}