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This is an Enterprise-only feature. Please install
KubeDB Enterprise Edition to try this feature.
Horizontal Scale MongoDB Shard
This guide will show you how to use KubeDB Enterprise operator to scale the shard of a MongoDB database.
Before You Begin
At first, you need to have a Kubernetes cluster, and the kubectl command-line tool must be configured to communicate with your cluster. If you do not already have a cluster, you can create one by using kind.
Install KubeDB Community and Enterprise operator in your cluster following the steps here.
You should be familiar with the following KubeDB concepts:
To keep everything isolated, we are going to use a separate namespace called demo throughout this tutorial.
$ kubectl create ns demo
namespace/demo created
Note: YAML files used in this tutorial are stored in docs/examples/mongodb directory of kubedb/docs repository.
Apply Horizontal Scaling on Sharded Database
Here, we are going to deploy a MongoDB sharded database using a supported version by KubeDB operator. Then we are going to apply horizontal scaling on it.
Prepare MongoDB Sharded Database
Now, we are going to deploy a MongoDB sharded database with version 3.6.8.
Deploy MongoDB Sharded Database
In this section, we are going to deploy a MongoDB sharded database. Then, in the next sections we will scale shards of the database using MongoDBOpsRequest CRD. Below is the YAML of the MongoDB CR that we are going to create,
apiVersion: kubedb.com/v1alpha2
kind: MongoDB
metadata:
name: mg-sharding
namespace: demo
spec:
version: 3.6.8-v1
shardTopology:
configServer:
replicas: 2
storage:
resources:
requests:
storage: 1Gi
storageClassName: standard
mongos:
replicas: 2
shard:
replicas: 2
shards: 3
storage:
resources:
requests:
storage: 1Gi
storageClassName: standard
Let’s create the MongoDB CR we have shown above,
$ kubectl create -f https://github.com/kubedb/docs/raw/v2021.01.02-rc.0/docs/examples/mongodb/scaling/mg-shard.yaml
mongodb.kubedb.com/mg-sharding created
Now, wait until mg-sharding has status Running. i.e,
$ kubectl get mg -n demo
NAME VERSION STATUS AGE
mg-sharding 3.6.8-v1 Running 10m
Verify Number of Shard and Shard Replicas
Let’s check the number of shards this database from the MongoDB object and the number of statefulsets it has,
$ kubectl get mongodb -n demo mg-sharding -o json | jq '.spec.shardTopology.shard.shards'
3
$ kubectl get sts -n demo
NAME READY AGE
mg-sharding-configsvr 2/2 23m
mg-sharding-mongos 2/2 22m
mg-sharding-shard0 2/2 23m
mg-sharding-shard1 2/2 23m
mg-sharding-shard2 2/2 23m
So, We can see from the both output that the database has 3 shards.
Now, Let’s check the number of replicas each shard has from the MongoDB object and the number of pod the statefulsets have,
$ kubectl get mongodb -n demo mg-sharding -o json | jq '.spec.shardTopology.shard.replicas'
2
$ kubectl get sts -n demo mg-sharding-shard0 -o json | jq '.spec.replicas'
2
We can see from both output that the database has 2 replicas in each shards.
Also, we can verify the number of shard from an internal mongodb command by execing into a mongos node.
First we need to get the username and password to connect to a mongos instance,
$ kubectl get secrets -n demo mg-sharding-auth -o jsonpath='{.data.\username}' | base64 -d
root
$ kubectl get secrets -n demo mg-sharding-auth -o jsonpath='{.data.\password}' | base64 -d
xBC-EwMFivFCgUlK
Now let’s connect to a mongos instance and run a mongodb internal command to check the number of shards,
$ kubectl exec -n demo mg-sharding-mongos-0 -- mongo admin -u root -p xBC-EwMFivFCgUlK --eval "sh.status()" --quiet
--- Sharding Status ---
sharding version: {
"_id" : 1,
"minCompatibleVersion" : 5,
"currentVersion" : 6,
"clusterId" : ObjectId("5f45fadd48c42afd901e6265")
}
shards:
{ "_id" : "shard0", "host" : "shard0/mg-sharding-shard0-0.mg-sharding-shard0-gvr.demo.svc.cluster.local:27017,mg-sharding-shard0-1.mg-sharding-shard0-gvr.demo.svc.cluster.local:27017", "state" : 1 }
{ "_id" : "shard1", "host" : "shard1/mg-sharding-shard1-0.mg-sharding-shard1-gvr.demo.svc.cluster.local:27017,mg-sharding-shard1-1.mg-sharding-shard1-gvr.demo.svc.cluster.local:27017", "state" : 1 }
{ "_id" : "shard2", "host" : "shard2/mg-sharding-shard2-0.mg-sharding-shard2-gvr.demo.svc.cluster.local:27017,mg-sharding-shard2-1.mg-sharding-shard2-gvr.demo.svc.cluster.local:27017", "state" : 1 }
active mongoses:
"3.6.8" : 2
autosplit:
Currently enabled: yes
balancer:
Currently enabled: yes
Currently running: no
Failed balancer rounds in last 5 attempts: 0
Migration Results for the last 24 hours:
No recent migrations
databases:
{ "_id" : "config", "primary" : "config", "partitioned" : true }
config.system.sessions
shard key: { "_id" : 1 }
unique: false
balancing: true
chunks:
shard0 1
{ "_id" : { "$minKey" : 1 } } -->> { "_id" : { "$maxKey" : 1 } } on : shard0 Timestamp(1, 0)
We can see from the above output that the number of shard is 3.
Also, we can verify the number of replicas each shard has from an internal mongodb command by execing into a shard node.
Now let’s connect to a shard instance and run a mongodb internal command to check the number of replicas,
$ kubectl exec -n demo mg-sharding-shard0-0 -- mongo admin -u root -p xBC-EwMFivFCgUlK --eval "db.adminCommand( { replSetGetStatus : 1 } ).members" --quiet
[
{
"_id" : 0,
"name" : "mg-sharding-shard0-0.mg-sharding-shard0-gvr.demo.svc.cluster.local:27017",
"health" : 1,
"state" : 1,
"stateStr" : "PRIMARY",
"uptime" : 2403,
"optime" : {
"ts" : Timestamp(1598424103, 1),
"t" : NumberLong(2)
},
"optimeDate" : ISODate("2020-08-26T06:41:43Z"),
"syncingTo" : "",
"syncSourceHost" : "",
"syncSourceId" : -1,
"infoMessage" : "",
"electionTime" : Timestamp(1598421711, 1),
"electionDate" : ISODate("2020-08-26T06:01:51Z"),
"configVersion" : 2,
"self" : true,
"lastHeartbeatMessage" : ""
},
{
"_id" : 1,
"name" : "mg-sharding-shard0-1.mg-sharding-shard0-gvr.demo.svc.cluster.local:27017",
"health" : 1,
"state" : 2,
"stateStr" : "SECONDARY",
"uptime" : 2380,
"optime" : {
"ts" : Timestamp(1598424103, 1),
"t" : NumberLong(2)
},
"optimeDurable" : {
"ts" : Timestamp(1598424103, 1),
"t" : NumberLong(2)
},
"optimeDate" : ISODate("2020-08-26T06:41:43Z"),
"optimeDurableDate" : ISODate("2020-08-26T06:41:43Z"),
"lastHeartbeat" : ISODate("2020-08-26T06:41:52.541Z"),
"lastHeartbeatRecv" : ISODate("2020-08-26T06:41:52.259Z"),
"pingMs" : NumberLong(0),
"lastHeartbeatMessage" : "",
"syncingTo" : "mg-sharding-shard0-0.mg-sharding-shard0-gvr.demo.svc.cluster.local:27017",
"syncSourceHost" : "mg-sharding-shard0-0.mg-sharding-shard0-gvr.demo.svc.cluster.local:27017",
"syncSourceId" : 0,
"infoMessage" : "",
"configVersion" : 2
}
]
We can see from the above output that the number of replica is 2.
Verify Number of ConfigServer
Let’s check the number of replicas this database has from the MongoDB object, number of pods the statefulset have,
$ kubectl get mongodb -n demo mg-sharding -o json | jq '.spec.shardTopology.configServer.replicas' 11:02:09
2
$ kubectl get sts -n demo mg-sharding-configsvr -o json | jq '.spec.replicas' 11:03:27
2
We can see from both command that the database has 2 replicas in the configServer.
Now let’s connect to a mongodb instance and run a mongodb internal command to check the number of replicas,
$ kubectl exec -n demo mg-sharding-configsvr-0 -- mongo admin -u root -p xBC-EwMFivFCgUlK --eval "db.adminCommand( { replSetGetStatus : 1 } ).members" --quiet 15:37:23
[
{
"_id" : 0,
"name" : "mg-sharding-configsvr-0.mg-sharding-configsvr-gvr.demo.svc.cluster.local:27017",
"health" : 1,
"state" : 1,
"stateStr" : "PRIMARY",
"uptime" : 388,
"optime" : {
"ts" : Timestamp(1598434641, 2),
"t" : NumberLong(2)
},
"optimeDate" : ISODate("2020-08-26T09:37:21Z"),
"syncingTo" : "",
"syncSourceHost" : "",
"syncSourceId" : -1,
"infoMessage" : "",
"electionTime" : Timestamp(1598434260, 1),
"electionDate" : ISODate("2020-08-26T09:31:00Z"),
"configVersion" : 2,
"self" : true,
"lastHeartbeatMessage" : ""
},
{
"_id" : 1,
"name" : "mg-sharding-configsvr-1.mg-sharding-configsvr-gvr.demo.svc.cluster.local:27017",
"health" : 1,
"state" : 2,
"stateStr" : "SECONDARY",
"uptime" : 360,
"optime" : {
"ts" : Timestamp(1598434641, 2),
"t" : NumberLong(2)
},
"optimeDurable" : {
"ts" : Timestamp(1598434641, 2),
"t" : NumberLong(2)
},
"optimeDate" : ISODate("2020-08-26T09:37:21Z"),
"optimeDurableDate" : ISODate("2020-08-26T09:37:21Z"),
"lastHeartbeat" : ISODate("2020-08-26T09:37:24.731Z"),
"lastHeartbeatRecv" : ISODate("2020-08-26T09:37:23.295Z"),
"pingMs" : NumberLong(0),
"lastHeartbeatMessage" : "",
"syncingTo" : "mg-sharding-configsvr-0.mg-sharding-configsvr-gvr.demo.svc.cluster.local:27017",
"syncSourceHost" : "mg-sharding-configsvr-0.mg-sharding-configsvr-gvr.demo.svc.cluster.local:27017",
"syncSourceId" : 0,
"infoMessage" : "",
"configVersion" : 2
}
]
We can see from the above output that the configServer has 2 nodes.
Verify Number of Mongos
Let’s check the number of replicas this database has from the MongoDB object, number of pods the statefulset have,
$ kubectl get mongodb -n demo mg-sharding -o json | jq '.spec.shardTopology.mongos.replicas' 11:02:09
2
$ kubectl get sts -n demo mg-sharding-mongos -o json | jq '.spec.replicas' 11:03:27
2
We can see from both command that the database has 2 replicas in the mongos.
Now let’s connect to a mongodb instance and run a mongodb internal command to check the number of replicas,
$ kubectl exec -n demo mg-sharding-mongos-0 -- mongo admin -u root -p xBC-EwMFivFCgUlK --eval "sh.status()" --quiet
--- Sharding Status ---
sharding version: {
"_id" : 1,
"minCompatibleVersion" : 5,
"currentVersion" : 6,
"clusterId" : ObjectId("5f463327bd21df369bb338bc")
}
shards:
{ "_id" : "shard0", "host" : "shard0/mg-sharding-shard0-0.mg-sharding-shard0-gvr.demo.svc.cluster.local:27017,mg-sharding-shard0-1.mg-sharding-shard0-gvr.demo.svc.cluster.local:27017", "state" : 1 }
{ "_id" : "shard1", "host" : "shard1/mg-sharding-shard1-0.mg-sharding-shard1-gvr.demo.svc.cluster.local:27017,mg-sharding-shard1-1.mg-sharding-shard1-gvr.demo.svc.cluster.local:27017", "state" : 1 }
{ "_id" : "shard2", "host" : "shard2/mg-sharding-shard2-0.mg-sharding-shard2-gvr.demo.svc.cluster.local:27017,mg-sharding-shard2-1.mg-sharding-shard2-gvr.demo.svc.cluster.local:27017", "state" : 1 }
active mongoses:
"3.6.8" : 2
autosplit:
Currently enabled: yes
balancer:
Currently enabled: yes
Currently running: no
Failed balancer rounds in last 5 attempts: 0
Migration Results for the last 24 hours:
No recent migrations
databases:
{ "_id" : "config", "primary" : "config", "partitioned" : true }
We can see from the above output that the mongos has 2 active nodes.
We are now ready to apply the MongoDBOpsRequest CR to update scale up and down all the components of the database.
Scale Up
Here, we are going to scale up all the components of the database to meet the desired number of replicas after scaling.
Create MongoDBOpsRequest
In order to scale up, we have to create a MongoDBOpsRequest CR with our configuration. Below is the YAML of the MongoDBOpsRequest CR that we are going to create,
apiVersion: ops.kubedb.com/v1alpha1
kind: MongoDBOpsRequest
metadata:
name: mops-hscale-up-shard
namespace: demo
spec:
type: HorizontalScaling
databaseRef:
name: mg-sharding
horizontalScaling:
shard:
shards: 4
replicas: 3
mongos:
replicas: 3
configServer:
replicas: 3
Here,
spec.databaseRef.name specifies that we are performing horizontal scaling operation on mops-hscale-up-shard database.spec.type specifies that we are performing HorizontalScaling on our database.spec.horizontalScaling.shard.shards specifies the desired number of shards after scaling.spec.horizontalScaling.shard.replicas specifies the desired number of replicas of each shard after scaling.spec.horizontalScaling.mongos.replicas specifies the desired replicas after scaling.spec.horizontalScaling.configServer.replicas specifies the desired replicas after scaling.
Note: If you don’t want to scale all the components together, you can only specify the components (shard, configServer and mongos) that you want to scale.
Let’s create the MongoDBOpsRequest CR we have shown above,
$ kubectl apply -f https://github.com/kubedb/docs/raw/v2021.01.02-rc.0/docs/examples/mongodb/scaling/horizontal-scaling/mops-hscale-up-shard.yaml
mongodbopsrequest.ops.kubedb.com/mops-hscale-up-shard created
Verify scaling up is successful
If everything goes well, KubeDB Enterprise operator will update the shard and replicas of MongoDB object and related StatefulSets and Pods.
Let’s wait for MongoDBOpsRequest to be Successful. Run the following command to watch MongoDBOpsRequest CR,
$ watch kubectl get mongodbopsrequest -n demo
Every 2.0s: kubectl get mongodbopsrequest -n demo
NAME TYPE STATUS AGE
mops-hscale-up-shard HorizontalScaling Successful 9m57s
We can see from the above output that the MongoDBOpsRequest has succeeded. If we describe the MongoDBOpsRequest we will get an overview of the steps that were followed to scale the database.
$ kubectl describe mongodbopsrequest -n demo mops-hscale-up-shard
Name: mops-hscale-up-shard
Namespace: demo
Labels: <none>
Annotations: <none>
API Version: ops.kubedb.com/v1alpha1
Kind: MongoDBOpsRequest
Metadata:
Creation Timestamp: 2020-09-30T05:36:41Z
Generation: 1
Managed Fields:
API Version: ops.kubedb.com/v1alpha1
Fields Type: FieldsV1
fieldsV1:
f:metadata:
f:annotations:
.:
f:kubectl.kubernetes.io/last-applied-configuration:
f:spec:
.:
f:databaseRef:
.:
f:name:
f:horizontalScaling:
.:
f:configServer:
.:
f:replicas:
f:mongos:
.:
f:replicas:
f:shard:
.:
f:replicas:
f:shards:
f:type:
Manager: kubectl-client-side-apply
Operation: Update
Time: 2020-09-30T05:36:41Z
API Version: ops.kubedb.com/v1alpha1
Fields Type: FieldsV1
fieldsV1:
f:status:
.:
f:conditions:
f:observedGeneration:
f:phase:
Manager: kubedb-enterprise
Operation: Update
Time: 2020-09-30T05:45:58Z
Resource Version: 1889687
Self Link: /apis/ops.kubedb.com/v1alpha1/namespaces/demo/mongodbopsrequests/mops-hscale-up-shard
UID: 5dd83c5d-81e1-494d-92c3-5dcbd8ebcaf2
Spec:
Database Ref:
Name: mg-sharding
Horizontal Scaling:
Config Server:
Replicas: 3
Mongos:
Replicas: 3
Shard:
Replicas: 3
Shards: 4
Type: HorizontalScaling
Status:
Conditions:
Last Transition Time: 2020-09-30T05:36:41Z
Message: MongoDB ops request is horizontally scaling database
Observed Generation: 1
Reason: HorizontalScaling
Status: True
Type: HorizontalScaling
Last Transition Time: 2020-09-30T05:45:58Z
Message: Successfully Resumed mongodb: mg-sharding
Observed Generation: 1
Reason: HaltDatabase
Status: False
Type: HaltDatabase
Last Transition Time: 2020-09-30T05:38:31Z
Message: Successfully Horizontally Scaled Up Shard Replicas
Observed Generation: 1
Reason: ScaleUpShardReplicas
Status: True
Type: ScaleUpShardReplicas
Last Transition Time: 2020-09-30T05:40:31Z
Message: Successfully Horizontally Scaled Up Shard
Observed Generation: 1
Reason: ScaleUpShard
Status: True
Type: ScaleUpShard
Last Transition Time: 2020-09-30T05:45:43Z
Message: Successfully Horizontally Scaled Up ConfigServer
Observed Generation: 1
Reason: ScaleUpConfigServer
Status: True
Type: ScaleUpConfigServer
Last Transition Time: 2020-09-30T05:45:58Z
Message: Successfully Horizontally Scaled Mongos
Observed Generation: 1
Reason: ScaleMongos
Status: True
Type: ScaleMongos
Last Transition Time: 2020-09-30T05:45:58Z
Message: Successfully Horizontally Scaled MongoDB
Observed Generation: 1
Reason: Successful
Status: True
Type: Successful
Observed Generation: 1
Phase: Successful
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal HaltDatabase 54m KubeDB Enterprise Operator Pausing MongoDB mg-sharding in Namespace demo
Normal HaltDatabase 54m KubeDB Enterprise Operator Successfully Halted MongoDB mg-sharding in Namespace demo
Normal ScaleUpShard 50m KubeDB Enterprise Operator Successfully Horizontally Scaled Up Shard
Normal HaltDatabase 50m KubeDB Enterprise Operator Pausing MongoDB mg-sharding in Namespace demo
Normal HaltDatabase 50m KubeDB Enterprise Operator Successfully Halted MongoDB mg-sharding in Namespace demo
Normal Progressing 50m KubeDB Enterprise Operator Successfully updated StatefulSets Resources
Normal Progressing 49m KubeDB Enterprise Operator Successfully updated StatefulSets Resources
Normal ScaleUpShard 49m KubeDB Enterprise Operator Successfully Horizontally Scaled Up Shard
Normal ScaleUpConfigServer 45m KubeDB Enterprise Operator Successfully Horizontally Scaled Up ConfigServer
Normal ScaleMongos 44m KubeDB Enterprise Operator Successfully Horizontally Scaled Mongos
Normal ResumeDatabase 44m KubeDB Enterprise Operator Resuming MongoDB
Normal ResumeDatabase 44m KubeDB Enterprise Operator Successfully Resumed mongodb
Normal Successful 44m KubeDB Enterprise Operator Successfully Horizontally Scaled Database
Verify Number of Shard and Shard Replicas
Now, we are going to verify the number of shards this database has from the MongoDB object, number of statefulsets it has,
$ kubectl get mongodb -n demo mg-sharding -o json | jq '.spec.shardTopology.shard.shards'
4
$ kubectl get sts -n demo
NAME READY AGE
mg-sharding-configsvr 2/2 58m
mg-sharding-mongos 2/2 57m
mg-sharding-shard0 3/3 58m
mg-sharding-shard1 3/3 58m
mg-sharding-shard2 3/3 58m
mg-sharding-shard3 3/3 15m
Now let’s connect to a mongos instance and run a mongodb internal command to check the number of shards,
$ kubectl exec -n demo mg-sharding-mongos-0 -- mongo admin -u root -p xBC-EwMFivFCgUlK --eval "sh.status()" --quiet
--- Sharding Status ---
sharding version: {
"_id" : 1,
"minCompatibleVersion" : 5,
"currentVersion" : 6,
"clusterId" : ObjectId("5f45fadd48c42afd901e6265")
}
shards:
{ "_id" : "shard0", "host" : "shard0/mg-sharding-shard0-0.mg-sharding-shard0-gvr.demo.svc.cluster.local:27017,mg-sharding-shard0-1.mg-sharding-shard0-gvr.demo.svc.cluster.local:27017,mg-sharding-shard0-2.mg-sharding-shard0-gvr.demo.svc.cluster.local:27017", "state" : 1 }
{ "_id" : "shard1", "host" : "shard1/mg-sharding-shard1-0.mg-sharding-shard1-gvr.demo.svc.cluster.local:27017,mg-sharding-shard1-1.mg-sharding-shard1-gvr.demo.svc.cluster.local:27017,mg-sharding-shard1-2.mg-sharding-shard1-gvr.demo.svc.cluster.local:27017", "state" : 1 }
{ "_id" : "shard2", "host" : "shard2/mg-sharding-shard2-0.mg-sharding-shard2-gvr.demo.svc.cluster.local:27017,mg-sharding-shard2-1.mg-sharding-shard2-gvr.demo.svc.cluster.local:27017,mg-sharding-shard2-2.mg-sharding-shard2-gvr.demo.svc.cluster.local:27017", "state" : 1 }
{ "_id" : "shard3", "host" : "shard3/mg-sharding-shard3-0.mg-sharding-shard3-gvr.demo.svc.cluster.local:27017,mg-sharding-shard3-1.mg-sharding-shard3-gvr.demo.svc.cluster.local:27017,mg-sharding-shard3-2.mg-sharding-shard3-gvr.demo.svc.cluster.local:27017", "state" : 1 }
active mongoses:
"3.6.8" : 2
autosplit:
Currently enabled: yes
balancer:
Currently enabled: yes
Currently running: no
Failed balancer rounds in last 5 attempts: 0
Migration Results for the last 24 hours:
No recent migrations
databases:
{ "_id" : "config", "primary" : "config", "partitioned" : true }
config.system.sessions
shard key: { "_id" : 1 }
unique: false
balancing: true
chunks:
shard0 1
{ "_id" : { "$minKey" : 1 } } -->> { "_id" : { "$maxKey" : 1 } } on : shard0 Timestamp(1, 0)
From all the above outputs we can see that the number of shards are 4.
Now, we are going to verify the number of replicas each shard has from the MongoDB object, number of pods the statefulset have,
$ kubectl get mongodb -n demo mg-sharding -o json | jq '.spec.shardTopology.shard.replicas'
3
$ kubectl get sts -n demo mg-sharding-shard0 -o json | jq '.spec.replicas'
3
Now let’s connect to a shard instance and run a mongodb internal command to check the number of replicas,
$ kubectl exec -n demo mg-sharding-shard0-0 -- mongo admin -u root -p xBC-EwMFivFCgUlK --eval "db.adminCommand( { replSetGetStatus : 1 } ).members" --quiet
[
{
"_id" : 0,
"name" : "mg-sharding-shard0-0.mg-sharding-shard0-gvr.demo.svc.cluster.local:27017",
"health" : 1,
"state" : 1,
"stateStr" : "PRIMARY",
"uptime" : 3907,
"optime" : {
"ts" : Timestamp(1598425614, 1),
"t" : NumberLong(2)
},
"optimeDate" : ISODate("2020-08-26T07:06:54Z"),
"syncingTo" : "",
"syncSourceHost" : "",
"syncSourceId" : -1,
"infoMessage" : "",
"electionTime" : Timestamp(1598421711, 1),
"electionDate" : ISODate("2020-08-26T06:01:51Z"),
"configVersion" : 3,
"self" : true,
"lastHeartbeatMessage" : ""
},
{
"_id" : 1,
"name" : "mg-sharding-shard0-1.mg-sharding-shard0-gvr.demo.svc.cluster.local:27017",
"health" : 1,
"state" : 2,
"stateStr" : "SECONDARY",
"uptime" : 3884,
"optime" : {
"ts" : Timestamp(1598425614, 1),
"t" : NumberLong(2)
},
"optimeDurable" : {
"ts" : Timestamp(1598425614, 1),
"t" : NumberLong(2)
},
"optimeDate" : ISODate("2020-08-26T07:06:54Z"),
"optimeDurableDate" : ISODate("2020-08-26T07:06:54Z"),
"lastHeartbeat" : ISODate("2020-08-26T07:06:57.308Z"),
"lastHeartbeatRecv" : ISODate("2020-08-26T07:06:57.383Z"),
"pingMs" : NumberLong(0),
"lastHeartbeatMessage" : "",
"syncingTo" : "mg-sharding-shard0-0.mg-sharding-shard0-gvr.demo.svc.cluster.local:27017",
"syncSourceHost" : "mg-sharding-shard0-0.mg-sharding-shard0-gvr.demo.svc.cluster.local:27017",
"syncSourceId" : 0,
"infoMessage" : "",
"configVersion" : 3
},
{
"_id" : 2,
"name" : "mg-sharding-shard0-2.mg-sharding-shard0-gvr.demo.svc.cluster.local:27017",
"health" : 1,
"state" : 2,
"stateStr" : "SECONDARY",
"uptime" : 1173,
"optime" : {
"ts" : Timestamp(1598425614, 1),
"t" : NumberLong(2)
},
"optimeDurable" : {
"ts" : Timestamp(1598425614, 1),
"t" : NumberLong(2)
},
"optimeDate" : ISODate("2020-08-26T07:06:54Z"),
"optimeDurableDate" : ISODate("2020-08-26T07:06:54Z"),
"lastHeartbeat" : ISODate("2020-08-26T07:06:57.491Z"),
"lastHeartbeatRecv" : ISODate("2020-08-26T07:06:56.659Z"),
"pingMs" : NumberLong(0),
"lastHeartbeatMessage" : "",
"syncingTo" : "mg-sharding-shard0-0.mg-sharding-shard0-gvr.demo.svc.cluster.local:27017",
"syncSourceHost" : "mg-sharding-shard0-0.mg-sharding-shard0-gvr.demo.svc.cluster.local:27017",
"syncSourceId" : 0,
"infoMessage" : "",
"configVersion" : 3
}
]
From all the above outputs we can see that the replicas of each shard has is 3.
Verify Number of ConfigServer Replicas
Now, we are going to verify the number of replicas this database has from the MongoDB object, number of pods the statefulset have,
$ kubectl get mongodb -n demo mg-sharding -o json | jq '.spec.shardTopology.configServer.replicas' 11:02:09
3
$ kubectl get sts -n demo mg-sharding-configsvr -o json | jq '.spec.replicas'
3
Now let’s connect to a mongodb instance and run a mongodb internal command to check the number of replicas,
$ kubectl exec -n demo mg-sharding-configsvr-0 -- mongo admin -u root -p xBC-EwMFivFCgUlK --eval "db.adminCommand( { replSetGetStatus : 1 } ).members" --quiet
[
{
"_id" : 0,
"name" : "mg-sharding-configsvr-0.mg-sharding-configsvr-gvr.demo.svc.cluster.local:27017",
"health" : 1,
"state" : 1,
"stateStr" : "PRIMARY",
"uptime" : 1058,
"optime" : {
"ts" : Timestamp(1598435313, 2),
"t" : NumberLong(2)
},
"optimeDate" : ISODate("2020-08-26T09:48:33Z"),
"syncingTo" : "",
"syncSourceHost" : "",
"syncSourceId" : -1,
"infoMessage" : "",
"electionTime" : Timestamp(1598434260, 1),
"electionDate" : ISODate("2020-08-26T09:31:00Z"),
"configVersion" : 3,
"self" : true,
"lastHeartbeatMessage" : ""
},
{
"_id" : 1,
"name" : "mg-sharding-configsvr-1.mg-sharding-configsvr-gvr.demo.svc.cluster.local:27017",
"health" : 1,
"state" : 2,
"stateStr" : "SECONDARY",
"uptime" : 1031,
"optime" : {
"ts" : Timestamp(1598435313, 2),
"t" : NumberLong(2)
},
"optimeDurable" : {
"ts" : Timestamp(1598435313, 2),
"t" : NumberLong(2)
},
"optimeDate" : ISODate("2020-08-26T09:48:33Z"),
"optimeDurableDate" : ISODate("2020-08-26T09:48:33Z"),
"lastHeartbeat" : ISODate("2020-08-26T09:48:35.250Z"),
"lastHeartbeatRecv" : ISODate("2020-08-26T09:48:34.860Z"),
"pingMs" : NumberLong(0),
"lastHeartbeatMessage" : "",
"syncingTo" : "mg-sharding-configsvr-0.mg-sharding-configsvr-gvr.demo.svc.cluster.local:27017",
"syncSourceHost" : "mg-sharding-configsvr-0.mg-sharding-configsvr-gvr.demo.svc.cluster.local:27017",
"syncSourceId" : 0,
"infoMessage" : "",
"configVersion" : 3
},
{
"_id" : 2,
"name" : "mg-sharding-configsvr-2.mg-sharding-configsvr-gvr.demo.svc.cluster.local:27017",
"health" : 1,
"state" : 2,
"stateStr" : "SECONDARY",
"uptime" : 460,
"optime" : {
"ts" : Timestamp(1598435313, 2),
"t" : NumberLong(2)
},
"optimeDurable" : {
"ts" : Timestamp(1598435313, 2),
"t" : NumberLong(2)
},
"optimeDate" : ISODate("2020-08-26T09:48:33Z"),
"optimeDurableDate" : ISODate("2020-08-26T09:48:33Z"),
"lastHeartbeat" : ISODate("2020-08-26T09:48:35.304Z"),
"lastHeartbeatRecv" : ISODate("2020-08-26T09:48:34.729Z"),
"pingMs" : NumberLong(0),
"lastHeartbeatMessage" : "",
"syncingTo" : "mg-sharding-configsvr-1.mg-sharding-configsvr-gvr.demo.svc.cluster.local:27017",
"syncSourceHost" : "mg-sharding-configsvr-1.mg-sharding-configsvr-gvr.demo.svc.cluster.local:27017",
"syncSourceId" : 1,
"infoMessage" : "",
"configVersion" : 3
}
]
From all the above outputs we can see that the replicas of the configServer is 3. That means we have successfully scaled up the replicas of the MongoDB configServer replicas.
Verify Number of Mongos Replicas
Now, we are going to verify the number of replicas this database has from the MongoDB object, number of pods the statefulset have,
$ kubectl get mongodb -n demo mg-sharding -o json | jq '.spec.shardTopology.mongos.replicas' 11:02:09
3
$ kubectl get sts -n demo mg-sharding-mongos -o json | jq '.spec.replicas'
3
Now let’s connect to a mongodb instance and run a mongodb internal command to check the number of replicas,
$ kubectl exec -n demo mg-sharding-mongos-0 -- mongo admin -u root -p xBC-EwMFivFCgUlK --eval "sh.status()" --quiet
--- Sharding Status ---
sharding version: {
"_id" : 1,
"minCompatibleVersion" : 5,
"currentVersion" : 6,
"clusterId" : ObjectId("5f463327bd21df369bb338bc")
}
shards:
{ "_id" : "shard0", "host" : "shard0/mg-sharding-shard0-0.mg-sharding-shard0-gvr.demo.svc.cluster.local:27017,mg-sharding-shard0-1.mg-sharding-shard0-gvr.demo.svc.cluster.local:27017", "state" : 1 }
{ "_id" : "shard1", "host" : "shard1/mg-sharding-shard1-0.mg-sharding-shard1-gvr.demo.svc.cluster.local:27017,mg-sharding-shard1-1.mg-sharding-shard1-gvr.demo.svc.cluster.local:27017", "state" : 1 }
{ "_id" : "shard2", "host" : "shard2/mg-sharding-shard2-0.mg-sharding-shard2-gvr.demo.svc.cluster.local:27017,mg-sharding-shard2-1.mg-sharding-shard2-gvr.demo.svc.cluster.local:27017", "state" : 1 }
active mongoses:
"3.6.8" : 3
autosplit:
Currently enabled: yes
balancer:
Currently enabled: yes
Currently running: no
Failed balancer rounds in last 5 attempts: 0
Migration Results for the last 24 hours:
No recent migrations
databases:
{ "_id" : "config", "primary" : "config", "partitioned" : true }
config.system.sessions
shard key: { "_id" : 1 }
unique: false
balancing: true
chunks:
shard0 1
{ "_id" : { "$minKey" : 1 } } -->> { "_id" : { "$maxKey" : 1 } } on : shard0 Timestamp(1, 0)
From all the above outputs we can see that the replicas of the mongos is 3. That means we have successfully scaled up the replicas of the MongoDB mongos replicas.
So, we have successfully scaled up all the components of the MongoDB database.
Scale Down
Here, we are going to scale down both the shard and their replicas to meet the desired number of replicas after scaling.
Create MongoDBOpsRequest
In order to scale down, we have to create a MongoDBOpsRequest CR with our configuration. Below is the YAML of the MongoDBOpsRequest CR that we are going to create,
apiVersion: ops.kubedb.com/v1alpha1
kind: MongoDBOpsRequest
metadata:
name: mops-hscale-down-shard
namespace: demo
spec:
type: HorizontalScaling
databaseRef:
name: mg-sharding
horizontalScaling:
shard:
shards: 3
replicas: 2
mongos:
replicas: 2
configServer:
replicas: 2
Here,
spec.databaseRef.name specifies that we are performing horizontal scaling operation on mops-hscale-down-shard database.spec.type specifies that we are performing HorizontalScaling on our database.spec.horizontalScaling.shard.shards specifies the desired number of shards after scaling.spec.horizontalScaling.shard.replicas specifies the desired number of replicas of each shard after scaling.spec.horizontalScaling.configServer.replicas specifies the desired replicas after scaling.spec.horizontalScaling.mongos.replicas specifies the desired replicas after scaling.
Note: If you don’t want to scale all the components together, you can only specify the components (shard, configServer and mongos) that you want to scale.
Let’s create the MongoDBOpsRequest CR we have shown above,
$ kubectl apply -f https://github.com/kubedb/docs/raw/v2021.01.02-rc.0/docs/examples/mongodb/scaling/horizontal-scaling/mops-hscale-down-shard.yaml
mongodbopsrequest.ops.kubedb.com/mops-hscale-down-shard created
Verify scaling down is successful
If everything goes well, KubeDB Enterprise operator will update the shards and replicas MongoDB object and related StatefulSets and Pods.
Let’s wait for MongoDBOpsRequest to be Successful. Run the following command to watch MongoDBOpsRequest CR,
$ watch kubectl get mongodbopsrequest -n demo
Every 2.0s: kubectl get mongodbopsrequest -n demo
NAME TYPE STATUS AGE
mops-hscale-down-shard HorizontalScaling Successful 81s
We can see from the above output that the MongoDBOpsRequest has succeeded. If we describe the MongoDBOpsRequest we will get an overview of the steps that were followed to scale down the the database.
$ kubectl describe mongodbopsrequest -n demo mops-hscale-down-shard
Name: mops-hscale-down-shard
Namespace: demo
Labels: <none>
Annotations: <none>
API Version: ops.kubedb.com/v1alpha1
Kind: MongoDBOpsRequest
Metadata:
Creation Timestamp: 2020-09-30T07:03:52Z
Generation: 1
Managed Fields:
API Version: ops.kubedb.com/v1alpha1
Fields Type: FieldsV1
fieldsV1:
f:metadata:
f:annotations:
.:
f:kubectl.kubernetes.io/last-applied-configuration:
f:spec:
.:
f:databaseRef:
.:
f:name:
f:horizontalScaling:
.:
f:configServer:
.:
f:replicas:
f:mongos:
.:
f:replicas:
f:shard:
.:
f:replicas:
f:shards:
f:type:
Manager: kubectl-client-side-apply
Operation: Update
Time: 2020-09-30T07:03:52Z
API Version: ops.kubedb.com/v1alpha1
Fields Type: FieldsV1
fieldsV1:
f:status:
.:
f:conditions:
f:observedGeneration:
f:phase:
Manager: kubedb-enterprise
Operation: Update
Time: 2020-09-30T07:05:34Z
Resource Version: 1908351
Self Link: /apis/ops.kubedb.com/v1alpha1/namespaces/demo/mongodbopsrequests/mops-hscale-down-shard
UID: 8edc1db9-a537-4bae-ac93-d1f5e9fcb758
Spec:
Database Ref:
Name: mg-sharding
Horizontal Scaling:
Config Server:
Replicas: 2
Mongos:
Replicas: 2
Shard:
Replicas: 2
Shards: 3
Type: HorizontalScaling
Status:
Conditions:
Last Transition Time: 2020-09-30T07:03:52Z
Message: MongoDB ops request is horizontally scaling database
Observed Generation: 1
Reason: HorizontalScaling
Status: True
Type: HorizontalScaling
Last Transition Time: 2020-09-30T07:05:34Z
Message: Successfully halted mongodb: mg-sharding
Observed Generation: 1
Reason: HaltDatabase
Status: True
Type: HaltDatabase
Last Transition Time: 2020-09-30T07:04:42Z
Message: Successfully Horizontally Scaled Down Shard Replicas
Observed Generation: 1
Reason: ScaleDownShardReplicas
Status: True
Type: ScaleDownShardReplicas
Last Transition Time: 2020-09-30T07:04:42Z
Message: Successfully started mongodb load balancer
Observed Generation: 1
Reason: StartingBalancer
Status: True
Type: StartingBalancer
Last Transition Time: 2020-09-30T07:05:04Z
Message: Successfully Horizontally Scaled Down Shard
Observed Generation: 1
Reason: ScaleDownShard
Status: True
Type: ScaleDownShard
Last Transition Time: 2020-09-30T07:05:14Z
Message: Successfully Horizontally Scaled Down ConfigServer
Observed Generation: 1
Reason: ScaleDownConfigServer
Status: True
Type: ScaleDownConfigServer
Last Transition Time: 2020-09-30T07:05:34Z
Message: Successfully Horizontally Scaled Mongos
Observed Generation: 1
Reason: ScaleMongos
Status: True
Type: ScaleMongos
Last Transition Time: 2020-09-30T07:05:34Z
Message: Successfully Horizontally Scaled MongoDB
Observed Generation: 1
Reason: Successful
Status: True
Type: Successful
Observed Generation: 1
Phase: Successful
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal HaltDatabase 2m17s KubeDB Enterprise Operator Pausing MongoDB mg-sharding in Namespace demo
Normal HaltDatabase 2m17s KubeDB Enterprise Operator Successfully Halted MongoDB mg-sharding in Namespace demo
Normal ScaleDownShardReplicas 87s KubeDB Enterprise Operator Successfully Horizontally Scaled Down Shard Replicas
Normal StartingBalancer 87s KubeDB Enterprise Operator Starting Balancer
Normal StartingBalancer 87s KubeDB Enterprise Operator Successfully Started Balancer
Normal ScaleDownShard 65s KubeDB Enterprise Operator Successfully Horizontally Scaled Down Shard
Normal ScaleDownConfigServer 55s KubeDB Enterprise Operator Successfully Horizontally Scaled Down ConfigServer
Normal ScaleMongos 35s KubeDB Enterprise Operator Successfully Horizontally Scaled Mongos
Normal ResumeDatabase 35s KubeDB Enterprise Operator Resuming MongoDB
Normal ResumeDatabase 35s KubeDB Enterprise Operator Successfully Resumed mongodb
Normal Successful 35s KubeDB Enterprise Operator Successfully Horizontally Scaled Database
Normal HaltDatabase 35s KubeDB Enterprise Operator Pausing MongoDB mg-sharding in Namespace demo
Normal HaltDatabase 35s KubeDB Enterprise Operator Successfully Halted MongoDB mg-sharding in Namespace demo
Verify Number of Shard and Shard Replicas
Now, we are going to verify the number of shards this database has from the MongoDB object, number of statefulsets it has,
$ kubectl get mongodb -n demo mg-sharding -o json | jq '.spec.shardTopology.shard.shards'
3
$ kubectl get sts -n demo
NAME READY AGE
mg-sharding-configsvr 2/2 78m
mg-sharding-mongos 2/2 77m
mg-sharding-shard0 2/2 78m
mg-sharding-shard1 2/2 78m
mg-sharding-shard2 2/2 78m
Now let’s connect to a mongos instance and run a mongodb internal command to check the number of shards,
$ kubectl exec -n demo mg-sharding-mongos-0 -- mongo admin -u root -p xBC-EwMFivFCgUlK --eval "sh.status()" --quiet
--- Sharding Status ---
sharding version: {
"_id" : 1,
"minCompatibleVersion" : 5,
"currentVersion" : 6,
"clusterId" : ObjectId("5f45fadd48c42afd901e6265")
}
shards:
{ "_id" : "shard0", "host" : "shard0/mg-sharding-shard0-0.mg-sharding-shard0-gvr.demo.svc.cluster.local:27017,mg-sharding-shard0-1.mg-sharding-shard0-gvr.demo.svc.cluster.local:27017", "state" : 1 }
{ "_id" : "shard1", "host" : "shard1/mg-sharding-shard1-0.mg-sharding-shard1-gvr.demo.svc.cluster.local:27017,mg-sharding-shard1-1.mg-sharding-shard1-gvr.demo.svc.cluster.local:27017", "state" : 1 }
{ "_id" : "shard2", "host" : "shard2/mg-sharding-shard2-0.mg-sharding-shard2-gvr.demo.svc.cluster.local:27017,mg-sharding-shard2-1.mg-sharding-shard2-gvr.demo.svc.cluster.local:27017", "state" : 1 }
active mongoses:
"3.6.8" : 2
autosplit:
Currently enabled: yes
balancer:
Currently enabled: yes
Currently running: no
Failed balancer rounds in last 5 attempts: 0
Migration Results for the last 24 hours:
No recent migrations
databases:
{ "_id" : "config", "primary" : "config", "partitioned" : true }
config.system.sessions
shard key: { "_id" : 1 }
unique: false
balancing: true
chunks:
shard0 1
{ "_id" : { "$minKey" : 1 } } -->> { "_id" : { "$maxKey" : 1 } } on : shard0 Timestamp(1, 0)
From all the above outputs we can see that the number of shards are 3.
Now, we are going to verify the number of replicas each shard has from the MongoDB object, number of pods the statefulset have,
$ kubectl get mongodb -n demo mg-sharding -o json | jq '.spec.shardTopology.shard.replicas' 13:05:25
2
$ kubectl get sts -n demo mg-sharding-shard0 -o json | jq '.spec.replicas' 13:05:30
2
Now let’s connect to a shard instance and run a mongodb internal command to check the number of replicas,
$ kubectl exec -n demo mg-sharding-shard0-0 -- mongo admin -u root -p xBC-EwMFivFCgUlK --eval "db.adminCommand( { replSetGetStatus : 1 } ).members" --quiet 13:06:31
[
{
"_id" : 0,
"name" : "mg-sharding-shard0-0.mg-sharding-shard0-gvr.demo.svc.cluster.local:27017",
"health" : 1,
"state" : 1,
"stateStr" : "PRIMARY",
"uptime" : 4784,
"optime" : {
"ts" : Timestamp(1598426494, 1),
"t" : NumberLong(2)
},
"optimeDate" : ISODate("2020-08-26T07:21:34Z"),
"syncingTo" : "",
"syncSourceHost" : "",
"syncSourceId" : -1,
"infoMessage" : "",
"electionTime" : Timestamp(1598421711, 1),
"electionDate" : ISODate("2020-08-26T06:01:51Z"),
"configVersion" : 4,
"self" : true,
"lastHeartbeatMessage" : ""
},
{
"_id" : 1,
"name" : "mg-sharding-shard0-1.mg-sharding-shard0-gvr.demo.svc.cluster.local:27017",
"health" : 1,
"state" : 2,
"stateStr" : "SECONDARY",
"uptime" : 4761,
"optime" : {
"ts" : Timestamp(1598426494, 1),
"t" : NumberLong(2)
},
"optimeDurable" : {
"ts" : Timestamp(1598426494, 1),
"t" : NumberLong(2)
},
"optimeDate" : ISODate("2020-08-26T07:21:34Z"),
"optimeDurableDate" : ISODate("2020-08-26T07:21:34Z"),
"lastHeartbeat" : ISODate("2020-08-26T07:21:34.403Z"),
"lastHeartbeatRecv" : ISODate("2020-08-26T07:21:34.383Z"),
"pingMs" : NumberLong(0),
"lastHeartbeatMessage" : "",
"syncingTo" : "mg-sharding-shard0-0.mg-sharding-shard0-gvr.demo.svc.cluster.local:27017",
"syncSourceHost" : "mg-sharding-shard0-0.mg-sharding-shard0-gvr.demo.svc.cluster.local:27017",
"syncSourceId" : 0,
"infoMessage" : "",
"configVersion" : 4
}
]
From all the above outputs we can see that the replicas of each shard has is 2.
Verify Number of ConfigServer Replicas
Now, we are going to verify the number of replicas this database has from the MongoDB object, number of pods the statefulset have,
$ kubectl get mongodb -n demo mg-sharding -o json | jq '.spec.shardTopology.configServer.replicas' 11:02:09
3
$ kubectl get sts -n demo mg-sharding-configsvr -o json | jq '.spec.replicas'
3
Now let’s connect to a mongodb instance and run a mongodb internal command to check the number of replicas,
$ kubectl exec -n demo mg-sharding-configsvr-0 -- mongo admin -u root -p xBC-EwMFivFCgUlK --eval "db.adminCommand( { replSetGetStatus : 1 } ).members" --quiet
[
{
"_id" : 0,
"name" : "mg-sharding-configsvr-0.mg-sharding-configsvr-gvr.demo.svc.cluster.local:27017",
"health" : 1,
"state" : 1,
"stateStr" : "PRIMARY",
"uptime" : 1316,
"optime" : {
"ts" : Timestamp(1598435569, 1),
"t" : NumberLong(2)
},
"optimeDate" : ISODate("2020-08-26T09:52:49Z"),
"syncingTo" : "",
"syncSourceHost" : "",
"syncSourceId" : -1,
"infoMessage" : "",
"electionTime" : Timestamp(1598434260, 1),
"electionDate" : ISODate("2020-08-26T09:31:00Z"),
"configVersion" : 4,
"self" : true,
"lastHeartbeatMessage" : ""
},
{
"_id" : 1,
"name" : "mg-sharding-configsvr-1.mg-sharding-configsvr-gvr.demo.svc.cluster.local:27017",
"health" : 1,
"state" : 2,
"stateStr" : "SECONDARY",
"uptime" : 1288,
"optime" : {
"ts" : Timestamp(1598435569, 1),
"t" : NumberLong(2)
},
"optimeDurable" : {
"ts" : Timestamp(1598435569, 1),
"t" : NumberLong(2)
},
"optimeDate" : ISODate("2020-08-26T09:52:49Z"),
"optimeDurableDate" : ISODate("2020-08-26T09:52:49Z"),
"lastHeartbeat" : ISODate("2020-08-26T09:52:52.348Z"),
"lastHeartbeatRecv" : ISODate("2020-08-26T09:52:52.347Z"),
"pingMs" : NumberLong(0),
"lastHeartbeatMessage" : "",
"syncingTo" : "mg-sharding-configsvr-0.mg-sharding-configsvr-gvr.demo.svc.cluster.local:27017",
"syncSourceHost" : "mg-sharding-configsvr-0.mg-sharding-configsvr-gvr.demo.svc.cluster.local:27017",
"syncSourceId" : 0,
"infoMessage" : "",
"configVersion" : 4
}
]
From all the above outputs we can see that the replicas of the configServer is 2. That means we have successfully scaled down the replicas of the MongoDB configServer replicas.
Verify Number of Mongos Replicas
Now, we are going to verify the number of replicas this database has from the MongoDB object, number of pods the statefulset have,
$ kubectl get mongodb -n demo mg-sharding -o json | jq '.spec.shardTopology.mongos.replicas' 11:02:09
2
$ kubectl get sts -n demo mg-sharding-mongos -o json | jq '.spec.replicas'
2
Now let’s connect to a mongodb instance and run a mongodb internal command to check the number of replicas,
$ kubectl exec -n demo mg-sharding-mongos-0 -- mongo admin -u root -p xBC-EwMFivFCgUlK --eval "sh.status()" --quiet
--- Sharding Status ---
sharding version: {
"_id" : 1,
"minCompatibleVersion" : 5,
"currentVersion" : 6,
"clusterId" : ObjectId("5f463327bd21df369bb338bc")
}
shards:
{ "_id" : "shard0", "host" : "shard0/mg-sharding-shard0-0.mg-sharding-shard0-gvr.demo.svc.cluster.local:27017,mg-sharding-shard0-1.mg-sharding-shard0-gvr.demo.svc.cluster.local:27017", "state" : 1 }
{ "_id" : "shard1", "host" : "shard1/mg-sharding-shard1-0.mg-sharding-shard1-gvr.demo.svc.cluster.local:27017,mg-sharding-shard1-1.mg-sharding-shard1-gvr.demo.svc.cluster.local:27017", "state" : 1 }
{ "_id" : "shard2", "host" : "shard2/mg-sharding-shard2-0.mg-sharding-shard2-gvr.demo.svc.cluster.local:27017,mg-sharding-shard2-1.mg-sharding-shard2-gvr.demo.svc.cluster.local:27017", "state" : 1 }
active mongoses:
"3.6.8" : 2
autosplit:
Currently enabled: yes
balancer:
Currently enabled: yes
Currently running: no
Failed balancer rounds in last 5 attempts: 0
Migration Results for the last 24 hours:
No recent migrations
databases:
{ "_id" : "config", "primary" : "config", "partitioned" : true }
config.system.sessions
shard key: { "_id" : 1 }
unique: false
balancing: true
chunks:
shard0 1
{ "_id" : { "$minKey" : 1 } } -->> { "_id" : { "$maxKey" : 1 } } on : shard0 Timestamp(1, 0)
From all the above outputs we can see that the replicas of the mongos is 2. That means we have successfully scaled down the replicas of the MongoDB mongos replicas.
So, we have successfully scaled down all the components of the MongoDB database.
Cleaning Up
To clean up the Kubernetes resources created by this tutorial, run:
kubectl delete mg -n demo mg-sharding
kubectl delete mongodbopsrequest -n demo mops-vscale-up-shard mops-vscale-down-shard
