Adding helm chart & documentation for redis-cluster related study ticket

[ric-plt/ric-dep.git] / docs / installation-rediscluster.rst

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+###################################################################################
+#  ============LICENSE_START=======================================================
+#
+#  ================================================================================
+#  Copyright (C) 2020 Hcl Technologies Limited.
+#  ================================================================================
+#  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.
+# ============LICENSE_END=========================================================
+###################################################################################
+
+Important
+^^^^^^^^^^
+The redis-cluster currently is NOT part of RIC platform & hence is completely optional.
+This piece of document has been created as part of delivery item for below jira ticket 
+https://jira.o-ran-sc.org/browse/RIC-109 
+This ticket is about assessing the feasibility of redis-cluster (with data sharding) 
+supporting desired pod anti-affinity for high availability as per the ticket.
+
+Overview
+^^^^^^^^^^
+This document describes the environment/conditions used to test the feasibility of Redis 
+cluster set-up as detailed in the above ticket. Redis Cluster is a distributed implementation 
+of Redis with high performance goals. More details at https://redis.io/topics/cluster-spec
+
+Environment Set-Up
+^^^^^^^^^^
+The set up was tested with kubernetes v1.19 cluster with 
+   #. Pod topology spread constraint enabled
+      Reference: https://kubernetes.io/docs/concepts/workloads/pods/pod-topology-spread-constraints
+   #. CEPH as the Cluster Storage Solution.
+         Reference: https://github.com/rook/rook.github.io/blob/master/docs/rook/v1.4/ceph-filesystem.md
+   #. Three worker nodes in the kubernet cluster
+
+Execution
+^^^^^^^^^^
+Once environment is set-up,  a redis-cluster can be set up using the helm-chart (also provided with 
+this commit). Once cluster is running, any master/slave of the redis instance pods can be deleted which
+will be compensated automatically by new instances
+
+At this stage the perl utility program (included with helm-chart) can be run. The helm chart installation
+output generates the requirement commands to invoke.
+
+This utility program identifies the missing anti-affinity(as per above ticket) of redis instances required
+in a redis-cluster. When executed it communicates to redis nodes to switch roles (e.g. master/slave)
+such that the end-state meets the desired anti-affinity. 
+
+