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Reconfigure MongoDB Shard
This guide will show you how to use KubeDB Enterprise operator to reconfigure a MongoDB shard.
Before You Begin
At first, you need to have a Kubernetes cluster, and the
kubectlcommand-line tool must be configured to communicate with your cluster.Install
KubeDBCommunity and Enterprise operator in your cluster following the steps here.You should be familiar with the following
KubeDBconcepts:
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.
Now, we are going to deploy a MongoDB sharded database using a supported version by KubeDB operator. Then we are going to apply MongoDBOpsRequest to reconfigure its configuration.
Prepare MongoDB Shard
Now, we are going to deploy a MongoDB sharded database with version 3.6.8.
Deploy MongoDB database
At first, we will create mongod.conf file containing required configuration settings.
$ cat mongod.conf
net:
maxIncomingConnections: 10000
Here, maxIncomingConnections is set to 10000, whereas the default value is 65536.
Now, we will create a configMap with this configuration file.
$ kubectl create configmap -n demo mg-custom-config --from-file=./mongod.conf
configmap/mg-custom-config created
In this section, we are going to create a MongoDB object specifying spec.configSecret field to apply this custom configuration. 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
configSecret:
name: mg-custom-config
storage:
resources:
requests:
storage: 1Gi
storageClassName: standard
mongos:
replicas: 2
configSecret:
name: mg-custom-config
shard:
replicas: 2
shards: 3
configSecret:
name: mg-custom-config
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/v2020.10.27-rc.1/docs/examples/mongodb/reconfigure/mg-shard-config.yaml
mongodb.kubedb.com/mg-sharding created
Now, wait until mg-sharding has status Running. i.e,
$ kubectl get mg -n demo 20:05:47
NAME VERSION STATUS AGE
mg-sharding 3.6.8-v1 Running 3m23s
Now, we will check if the database has started with the custom configuration we have provided.
First we need to get the username and password to connect to a mongodb instance,
$ kubectl get secrets -n demo mg-sharding-auth -o jsonpath='{.data.\username}' | base64 -d 11:09:51
root
$ kubectl get secrets -n demo mg-sharding-auth -o jsonpath='{.data.\password}' | base64 -d 11:10:44
Dv8F55zVNiEkhHM6
Now let’s connect to a mongodb instance from each type of nodes and run a mongodb internal command to check the configuration we have provided.
$ kubectl exec -n demo mg-sharding-mongos-0 -- mongo admin -u root -p Dv8F55zVNiEkhHM6 --eval "db._adminCommand( {getCmdLineOpts: 1}).parsed.net" --quiet
{
"bindIp" : "0.0.0.0",
"maxIncomingConnections" : 10000,
"port" : 27017,
"ssl" : {
"mode" : "disabled"
}
}
$ kubectl exec -n demo mg-sharding-configsvr-0 -- mongo admin -u root -p Dv8F55zVNiEkhHM6 --eval "db._adminCommand( {getCmdLineOpts: 1}).parsed.net" --quiet
{
"bindIp" : "0.0.0.0",
"maxIncomingConnections" : 10000,
"port" : 27017,
"ssl" : {
"mode" : "disabled"
}
}
$ kubectl exec -n demo mg-sharding-shard0-0 -- mongo admin -u root -p Dv8F55zVNiEkhHM6 --eval "db._adminCommand( {getCmdLineOpts: 1}).parsed.net" --quiet
{
"bindIp" : "0.0.0.0",
"maxIncomingConnections" : 10000,
"port" : 27017,
"ssl" : {
"mode" : "disabled"
}
}
As we can see from the configuration of running mongodb, the value of maxIncomingConnections has been set to 10000 in all nodes.
Reconfigure using new ConfigMap
Now we will reconfigure this database to set maxIncomingConnections to 20000.
Now, we will edit the mongod.conf file containing required configuration settings.
$ cat mongod.conf
net:
maxIncomingConnections: 20000
Then, we will create a new configMap with this configuration file.
$ kubectl create configmap -n demo new-custom-config --from-file=./mongod.conf
configmap/mg-custom-config created
Create MongoDBOpsRequest
Now, we will use this configMap to replace the previous configMap using a MongoDBOpsRequest CR. The MongoDBOpsRequest yaml is given below,
apiVersion: ops.kubedb.com/v1alpha1
kind: MongoDBOpsRequest
metadata:
name: mops-reconfigure-shard
namespace: demo
spec:
type: Reconfigure
databaseRef:
name: mg-sharding
customConfig:
shard:
configMap:
name: new-custom-config
configServer:
configMap:
name: new-custom-config
mongos:
configMap:
name: new-custom-config
Here,
spec.databaseRef.namespecifies that we are reconfiguringmops-reconfigure-sharddatabase.spec.typespecifies that we are performingReconfigureon our database.spec.customConfig.shard.configMap.namespecifies the name of the new configmap for shard nodes.spec.customConfig.configServer.configMap.namespecifies the name of the new configmap for configServer nodes.spec.customConfig.mongos.configMap.namespecifies the name of the new configmap for mongos nodes.
Note: If you don’t want to reconfigure all the components together, you can only specify the components (shard, configServer and mongos) that you want to reconfigure.
Let’s create the MongoDBOpsRequest CR we have shown above,
$ kubectl apply -f https://github.com/kubedb/docs/raw/v2020.10.27-rc.1/docs/examples/mongodb/reconfigure/mops-reconfigure-shard.yaml
mongodbopsrequest.ops.kubedb.com/mops-reconfigure-shard created
Verify the new configuration is working
If everything goes well, KubeDB Enterprise operator will update the configSource of MongoDB object.
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-reconfigure-shard Reconfigure Successful 3m8s
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 reconfigure the database.
$ kubectl describe mongodbopsrequest -n demo mops-reconfigure-shard
Name: mops-reconfigure-shard
Namespace: demo
Labels: <none>
Annotations: <none>
API Version: ops.kubedb.com/v1alpha1
Kind: MongoDBOpsRequest
Metadata:
Creation Timestamp: 2020-09-29T17:16:47Z
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:customConfig:
.:
f:configServer:
.:
f:configMap:
.:
f:name:
f:mongos:
.:
f:configMap:
.:
f:name:
f:shard:
.:
f:configMap:
.:
f:name:
f:databaseRef:
.:
f:name:
f:type:
Manager: kubectl-client-side-apply
Operation: Update
Time: 2020-09-29T17:16:47Z
API Version: ops.kubedb.com/v1alpha1
Fields Type: FieldsV1
fieldsV1:
f:status:
.:
f:conditions:
f:observedGeneration:
f:phase:
Manager: kubedb-enterprise
Operation: Update
Time: 2020-09-29T17:20:43Z
Resource Version: 1857484
Self Link: /apis/ops.kubedb.com/v1alpha1/namespaces/demo/mongodbopsrequests/mops-reconfigure-shard
UID: fa02b9c6-83bd-4835-b72f-a027a0c8cf51
Spec:
Custom Config:
Config Server:
Config Map:
Name: new-custom-config
Mongos:
Config Map:
Name: new-custom-config
Shard:
Config Map:
Name: new-custom-config
Database Ref:
Name: mg-sharding
Type: Reconfigure
Status:
Conditions:
Last Transition Time: 2020-09-29T17:16:47Z
Message: MongoDB ops request is reconfiguring database
Observed Generation: 1
Reason: Reconfigure
Status: True
Type: Reconfigure
Last Transition Time: 2020-09-29T17:16:47Z
Message: Successfully halted mongodb: mg-sharding
Observed Generation: 1
Reason: HaltDatabase
Status: True
Type: HaltDatabase
Last Transition Time: 2020-09-29T17:17:32Z
Message: Successfully Reconfigured MongoDB
Observed Generation: 1
Reason: ReconfigureMongos
Status: True
Type: ReconfigureMongos
Last Transition Time: 2020-09-29T17:18:22Z
Message: Successfully Reconfigured MongoDB
Observed Generation: 1
Reason: ReconfigureConfigServer
Status: True
Type: ReconfigureConfigServer
Last Transition Time: 2020-09-29T17:20:42Z
Message: Successfully Reconfigured MongoDB
Observed Generation: 1
Reason: ReconfigureShard
Status: True
Type: ReconfigureShard
Last Transition Time: 2020-09-29T17:20:42Z
Message: Successfully Resumed mongodb: mg-sharding
Observed Generation: 1
Reason: ResumeDatabase
Status: True
Type: ResumeDatabase
Last Transition Time: 2020-09-29T17:20:43Z
Message: Successfully completed the modification process.
Observed Generation: 1
Reason: Successful
Status: True
Type: Successful
Observed Generation: 1
Phase: Successful
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal HaltDatabase 5m KubeDB Enterprise Operator Pausing MongoDB mg-sharding in Namespace demo
Normal HaltDatabase 5m KubeDB Enterprise Operator Successfully Halted MongoDB mg-sharding in Namespace demo
Normal ReconfigureMongos 4m15s KubeDB Enterprise Operator Successfully Reconfigured MongoDB
Normal ReconfigureConfigServer 3m25s KubeDB Enterprise Operator Successfully Reconfigured MongoDB
Normal ReconfigureShard 65s KubeDB Enterprise Operator Successfully Reconfigured MongoDB
Normal ResumeDatabase 65s KubeDB Enterprise Operator Resuming MongoDB
Normal ResumeDatabase 65s KubeDB Enterprise Operator Successfully Started Balancer
Normal Successful 65s KubeDB Enterprise Operator Successfully Reconfigured Database
Normal Successful 64s KubeDB Enterprise Operator Successfully Reconfigured Database
Now let’s connect to a mongodb instance from each type of nodes and run a mongodb internal command to check the new configuration we have provided.
$ kubectl exec -n demo mg-sharding-mongos-0 -- mongo admin -u root -p Dv8F55zVNiEkhHM6 --eval "db._adminCommand( {getCmdLineOpts: 1}).parsed.net" --quiet
{
"bindIp" : "0.0.0.0",
"maxIncomingConnections" : 20000,
"port" : 27017,
"ssl" : {
"mode" : "disabled"
}
}
$ kubectl exec -n demo mg-sharding-configsvr-0 -- mongo admin -u root -p Dv8F55zVNiEkhHM6 --eval "db._adminCommand( {getCmdLineOpts: 1}).parsed.net" --quiet
{
"bindIp" : "0.0.0.0",
"maxIncomingConnections" : 20000,
"port" : 27017,
"ssl" : {
"mode" : "disabled"
}
}
$ kubectl exec -n demo mg-sharding-shard0-0 -- mongo admin -u root -p Dv8F55zVNiEkhHM6 --eval "db._adminCommand( {getCmdLineOpts: 1}).parsed.net" --quiet
{
"bindIp" : "0.0.0.0",
"maxIncomingConnections" : 20000,
"port" : 27017,
"ssl" : {
"mode" : "disabled"
}
}
As we can see from the configuration of running mongodb, the value of maxIncomingConnections has been changed from 10000 to 20000 in all type of nodes. So the reconfiguration of the database is successful.
Reconfigure using new Data
Now we will reconfigure this database again to set maxIncomingConnections to 30000. This time we won’t use a new configMap. We will use the data field of the MongoDBOpsRequest. This will merge the new config in the existing configMap.
Create MongoDBOpsRequest
Now, we will use the new configuration in the data field in the MongoDBOpsRequest CR. The MongoDBOpsRequest yaml is given below,
apiVersion: ops.kubedb.com/v1alpha1
kind: MongoDBOpsRequest
metadata:
name: mops-reconfigure-data-shard
namespace: demo
spec:
type: Reconfigure
databaseRef:
name: mg-sharding
customConfig:
shard:
data:
mongod.conf: |
net:
maxIncomingConnections: 30000
configServer:
data:
mongod.conf: |
net:
maxIncomingConnections: 30000
mongos:
data:
mongod.conf: |
net:
maxIncomingConnections: 30000
Here,
spec.databaseRef.namespecifies that we are reconfiguringmops-reconfigure-data-sharddatabase.spec.typespecifies that we are performingReconfigureon our database.spec.customConfig.shard.dataspecifies the new configuration that will be merged in the existing configMap for shard nodes.spec.customConfig.configServer.dataspecifies the new configuration that will be merged in the existing configMap for configServer nodes.spec.customConfig.mongos.dataspecifies the new configuration that will be merged in the existing configMap for mongos nodes.
Note: If you don’t want to reconfigure all the components together, you can only specify the components (shard, configServer and mongos) that you want to reconfigure.
Let’s create the MongoDBOpsRequest CR we have shown above,
$ kubectl apply -f https://github.com/kubedb/docs/raw/v2020.10.27-rc.1/docs/examples/mongodb/reconfigure/mops-reconfigure-data-shard.yaml
mongodbopsrequest.ops.kubedb.com/mops-reconfigure-data-shard created
Verify the new configuration is working
If everything goes well, KubeDB Enterprise operator will merge this new config with the existing configuration.
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-reconfigure-data-shard Reconfigure Successful 3m24s
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 reconfigure the database.
$ kubectl describe mongodbopsrequest -n demo mops-reconfigure-data-shard
Name: mops-reconfigure-data-shard
Namespace: demo
Labels: <none>
Annotations: <none>
API Version: ops.kubedb.com/v1alpha1
Kind: MongoDBOpsRequest
Metadata:
Creation Timestamp: 2020-09-29T17:23:23Z
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:customConfig:
.:
f:configServer:
.:
f:data:
.:
f:mongod.conf:
f:mongos:
.:
f:data:
.:
f:mongod.conf:
f:shard:
.:
f:data:
.:
f:mongod.conf:
f:databaseRef:
.:
f:name:
f:type:
Manager: kubectl-client-side-apply
Operation: Update
Time: 2020-09-29T17:23:23Z
API Version: ops.kubedb.com/v1alpha1
Fields Type: FieldsV1
fieldsV1:
f:status:
.:
f:conditions:
f:observedGeneration:
f:phase:
Manager: kubedb-enterprise
Operation: Update
Time: 2020-09-29T17:27:08Z
Resource Version: 1858942
Self Link: /apis/ops.kubedb.com/v1alpha1/namespaces/demo/mongodbopsrequests/mops-reconfigure-data-shard
UID: 05849063-3e57-4441-a6da-7a1c5393989a
Spec:
Custom Config:
Config Server:
Data:
mongod.conf: net:
maxIncomingConnections: 30000
Mongos:
Data:
mongod.conf: net:
maxIncomingConnections: 30000
Shard:
Data:
mongod.conf: net:
maxIncomingConnections: 30000
Database Ref:
Name: mg-sharding
Type: Reconfigure
Status:
Conditions:
Last Transition Time: 2020-09-29T17:23:23Z
Message: MongoDB ops request is reconfiguring database
Observed Generation: 1
Reason: Reconfigure
Status: True
Type: Reconfigure
Last Transition Time: 2020-09-29T17:24:08Z
Message: Successfully Reconfigured MongoDB
Observed Generation: 1
Reason: ReconfigureMongos
Status: True
Type: ReconfigureMongos
Last Transition Time: 2020-09-29T17:24:58Z
Message: Successfully Reconfigured MongoDB
Observed Generation: 1
Reason: ReconfigureConfigServer
Status: True
Type: ReconfigureConfigServer
Last Transition Time: 2020-09-29T17:27:08Z
Message: Successfully Reconfigured MongoDB
Observed Generation: 1
Reason: ReconfigureShard
Status: True
Type: ReconfigureShard
Last Transition Time: 2020-09-29T17:27:08Z
Message: Successfully Resumed mongodb: mg-sharding
Observed Generation: 1
Reason: ResumeDatabase
Status: True
Type: ResumeDatabase
Last Transition Time: 2020-09-29T17:27:08Z
Message: Successfully completed the modification process.
Observed Generation: 1
Reason: Successful
Status: True
Type: Successful
Observed Generation: 1
Phase: Successful
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal ReconfigureMongos 16m KubeDB Enterprise Operator Successfully Reconfigured MongoDB
Normal ReconfigureConfigServer 15m KubeDB Enterprise Operator Successfully Reconfigured MongoDB
Normal ReconfigureShard 13m KubeDB Enterprise Operator Successfully Reconfigured MongoDB
Normal ResumeDatabase 13m KubeDB Enterprise Operator Resuming MongoDB
Normal ResumeDatabase 13m KubeDB Enterprise Operator Successfully Started Balancer
Normal Successful 13m KubeDB Enterprise Operator Successfully Reconfigured Database
Normal Successful 13m KubeDB Enterprise Operator Successfully Reconfigured Database
Now let’s connect to a mongodb instance from each type of nodes and run a mongodb internal command to check the new configuration we have provided.
$ kubectl exec -n demo mg-sharding-mongos-0 -- mongo admin -u root -p Dv8F55zVNiEkhHM6 --eval "db._adminCommand( {getCmdLineOpts: 1}).parsed.net" --quiet
{
"bindIp" : "0.0.0.0",
"maxIncomingConnections" : 30000,
"port" : 27017,
"ssl" : {
"mode" : "disabled"
}
}
$ kubectl exec -n demo mg-sharding-configsvr-0 -- mongo admin -u root -p Dv8F55zVNiEkhHM6 --eval "db._adminCommand( {getCmdLineOpts: 1}).parsed.net" --quiet
{
"bindIp" : "0.0.0.0",
"maxIncomingConnections" : 30000,
"port" : 27017,
"ssl" : {
"mode" : "disabled"
}
}
$ kubectl exec -n demo mg-sharding-shard0-0 -- mongo admin -u root -p Dv8F55zVNiEkhHM6 --eval "db._adminCommand( {getCmdLineOpts: 1}).parsed.net" --quiet
{
"bindIp" : "0.0.0.0",
"maxIncomingConnections" : 30000,
"port" : 27017,
"ssl" : {
"mode" : "disabled"
}
}
As we can see from the configuration of running mongodb, the value of maxIncomingConnections has been changed from 20000 to 30000 in all nodes. So the reconfiguration of the database using the data field is successful.
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-reconfigure-shard mops-reconfigure-data-shard