PLT-6080 moving clustering to memberlist (#6499)

* PLT-6080 adding cluster discovery service

* Adding memberlist lib

* Adding memberlist lib

* WIP

* WIP

* WIP

* WIP

* Rolling back config changes

* Fixing make file

* Fixing config for cluster

* WIP

* Fixing system console for clustering

* Fixing default config

* Fixing config

* Fixing system console for clustering

* Tweaking hub setting

* Bumping up time

* merging vendor dir

* Updating vendor dir

* Fixing unit test

* Fixing bad merge

* Remove some testing code

* Moving comment

* PLT-6868 adding db ping retry

* Removing unused loc strings

* Adding defer to cancel

model/cluster_message.go

@@ -0,0 +1,55 @@
+// Copyright (c) 2016-present Mattermost, Inc. All Rights Reserved.
+// See License.txt for license information.
+
+package model
+
+import (
+	"encoding/json"
+	"io"
+)
+
+const (
+	CLUSTER_EVENT_PUBLISH                                           = "publish"
+	CLUSTER_EVENT_UPDATE_STATUS                                     = "update_status"
+	CLUSTER_EVENT_INVALIDATE_ALL_CACHES                             = "inv_all_caches"
+	CLUSTER_EVENT_INVALIDATE_CACHE_FOR_REACTIONS                    = "inv_reactions"
+	CLUSTER_EVENT_INVALIDATE_CACHE_FOR_WEBHOOK                      = "inv_webhook"
+	CLUSTER_EVENT_INVALIDATE_CACHE_FOR_CHANNEL_POSTS                = "inv_channel_posts"
+	CLUSTER_EVENT_INVALIDATE_CACHE_FOR_CHANNEL_MEMBERS_NOTIFY_PROPS = "inv_channel_members_notify_props"
+	CLUSTER_EVENT_INVALIDATE_CACHE_FOR_CHANNEL_MEMBERS              = "inv_channel_members"
+	CLUSTER_EVENT_INVALIDATE_CACHE_FOR_CHANNEL_BY_NAME              = "inv_channel_name"
+	CLUSTER_EVENT_INVALIDATE_CACHE_FOR_CHANNEL                      = "inv_channel"
+	CLUSTER_EVENT_INVALIDATE_CACHE_FOR_USER                         = "inv_user"
+	CLUSTER_EVENT_CLEAR_SESSION_CACHE_FOR_USER                      = "clear_session_user"
+
+	CLUSTER_SEND_BEST_EFFORT = "best_effort"
+	CLUSTER_SEND_RELIABLE    = "reliable"
+)
+
+type ClusterMessage struct {
+	Event            string            `json:"event"`
+	SendType         string            `json:"-"`
+	WaitForAllToSend bool              `json:"-"`
+	Data             string            `json:"data,omitempty"`
+	Props            map[string]string `json:"props,omitempty"`
+}
+
+func (o *ClusterMessage) ToJson() string {
+	b, err := json.Marshal(o)
+	if err != nil {
+		return ""
+	} else {
+		return string(b)
+	}
+}
+
+func ClusterMessageFromJson(data io.Reader) *ClusterMessage {
+	decoder := json.NewDecoder(data)
+	var o ClusterMessage
+	err := decoder.Decode(&o)
+	if err == nil {
+		return &o
+	} else {
+		return nil
+	}
+}