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Reconfigure MongoDB Replicaset Database
This guide will show you how to use KubeDB Enterprise operator to reconfigure a MongoDB Replicaset.
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 Replicaset using a supported version by KubeDB operator. Then we are going to apply MongoDBOpsRequest to reconfigure its configuration.
Prepare MongoDB Replicaset
Now, we are going to deploy a MongoDB Replicaset database with version 3.6.8.
Deploy MongoDB
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,
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/reconfigure/mg-replicaset-config.yaml
mongodb.kubedb.com/mg-replicaset created
Now, wait until mg-replicaset has status Running. i.e,
$ kubectl get mg -n demo 20:05:47
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-replicaset-auth -o jsonpath='{.data.\username}' | base64 -d 11:09:51
root
$ kubectl get secrets -n demo mg-replicaset-auth -o jsonpath='{.data.\password}' | base64 -d 11:10:44
nrKuxni0wDSMrgwy
Now let’s connect to a mongodb instance and run a mongodb internal command to check the configuration we have provided.
$ kubectl exec -n demo mg-replicaset-0 -- mongo admin -u root -p nrKuxni0wDSMrgwy --eval "db._adminCommand( {getCmdLineOpts: 1})" --quiet 18:35:59
As we can see from the configuration of running mongodb, the value of maxIncomingConnections has been set to 10000.
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-replicaset
namespace: demo
spec:
type: Reconfigure
databaseRef:
name: mg-replicaset
customConfig:
replicaSet:
configMap:
name: new-custom-config
Here,
spec.databaseRef.namespecifies that we are reconfiguringmops-reconfigure-replicasetdatabase.spec.typespecifies that we are performingReconfigureon our database.spec.customConfig.replicaSet.configMap.namespecifies the name of the new configmap.
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/reconfigure/mops-reconfigure-replicaset.yaml
mongodbopsrequest.ops.kubedb.com/mops-reconfigure-replicaset 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-replicaset Reconfigure Successful 113s
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-replicaset
Name: mops-reconfigure-replicaset
Namespace: demo
Labels: <none>
Annotations: API Version: ops.kubedb.com/v1alpha1
Kind: MongoDBOpsRequest
Metadata:
Creation Timestamp: 2020-08-26T18:40:06Z
Finalizers:
kubedb.com
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:replicaSet:
.:
f:configMap:
.:
f:name:
f:databaseRef:
.:
f:name:
f:type:
Manager: kubectl
Operation: Update
Time: 2020-08-26T18:40:06Z
API Version: ops.kubedb.com/v1alpha1
Fields Type: FieldsV1
fieldsV1:
f:metadata:
f:finalizers:
f:status:
.:
f:conditions:
f:observedGeneration:
f:phase:
Manager: kubedb-enterprise
Operation: Update
Time: 2020-08-26T18:41:26Z
Resource Version: 6294401
Self Link: /apis/ops.kubedb.com/v1alpha1/namespaces/demo/mongodbopsrequests/mops-reconfigure-replicaset
UID: bd17e9ed-35ed-4ab9-a844-659800ef4f39
Spec:
Custom Config:
ReplicaSet:
Config Map:
Name: new-custom-config
Database Ref:
Name: mg-replicaset
Type: Reconfigure
Status:
Conditions:
Last Transition Time: 2020-08-26T18:40:06Z
Message: MongoDB ops request is being processed
Observed Generation: 1
Reason: Scaling
Status: True
Type: Scaling
Last Transition Time: 2020-08-26T18:40:06Z
Message: Successfully halted mongodb: mg-replicaset
Observed Generation: 1
Reason: HaltDatabase
Status: True
Type: HaltDatabase
Last Transition Time: 2020-08-26T18:41:26Z
Message: Successfully Reconfigured mongodb
Observed Generation: 1
Reason: ReconfigureReplicaset
Status: True
Type: ReconfigureReplicaset
Last Transition Time: 2020-08-26T18:41:26Z
Message: Succefully Resumed mongodb: mg-replicaset
Observed Generation: 1
Reason: ResumeDatabase
Status: True
Type: ResumeDatabase
Last Transition Time: 2020-08-26T18:41:26Z
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 2m23s KubeDB Enterprise Operator Pausing Mongodb mg-replicaset in Namespace demo
Normal HaltDatabase 2m23s KubeDB Enterprise Operator Successfully Halted Mongodb mg-replicaset in Namespace demo
Normal ReconfigureReplicaset 63s KubeDB Enterprise Operator Successfully Reconfigured mongodb
Normal ResumeDatabase 63s KubeDB Enterprise Operator Resuming MongoDB
Normal ResumeDatabase 63s KubeDB Enterprise Operator Successfully Started Balancer
Normal Successful 63s KubeDB Enterprise Operator Successfully Reconfigured Database
Now let’s connect to a mongodb instance and run a mongodb internal command to check the new configuration we have provided.
$ kubectl exec -n demo mg-replicaset-0 -- mongo admin -u root -p nrKuxni0wDSMrgwy --eval "db._adminCommand( {getCmdLineOpts: 1})" --quiet
{
"argv" : [
"mongod",
"--dbpath=/data/db",
"--auth",
"--bind_ip=0.0.0.0",
"--port=27017",
"--sslMode=disabled",
"--replSet=replicaset",
"--keyFile=/data/configdb/key.txt",
"--clusterAuthMode=keyFile",
"--config=/data/configdb/mongod.conf"
],
"parsed" : {
"config" : "/data/configdb/mongod.conf",
"net" : {
"bindIp" : "0.0.0.0",
"maxIncomingConnections" : 20000,
"port" : 27017,
"ssl" : {
"mode" : "disabled"
}
},
"replication" : {
"replSet" : "replicaset"
},
"security" : {
"authorization" : "enabled",
"clusterAuthMode" : "keyFile",
"keyFile" : "/data/configdb/key.txt"
},
"storage" : {
"dbPath" : "/data/db"
}
},
"ok" : 1,
"operationTime" : Timestamp(1598467358, 1),
"$clusterTime" : {
"clusterTime" : Timestamp(1598467358, 1),
"signature" : {
"hash" : BinData(0,"ZumeKUzV3YmFMlmHy9twU1tJxlw="),
"keyId" : NumberLong("6865318254139670530")
}
}
}
As we can see from the configuration of running mongodb, the value of maxIncomingConnections has been changed from 10000 to 20000. 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-replicaset
namespace: demo
spec:
type: Reconfigure
databaseRef:
name: mg-replicaset
customConfig:
replicaSet:
data:
mongod.conf: |
net:
maxIncomingConnections: 30000
Here,
spec.databaseRef.namespecifies that we are reconfiguringmops-reconfigure-data-replicasetdatabase.spec.typespecifies that we are performingReconfigureon our database.spec.customConfig.replicaSet.dataspecifies the new configuration that will be merged in the existing configMap.
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/reconfigure/mops-reconfigure-data-replicaset.yaml
mongodbopsrequest.ops.kubedb.com/mops-reconfigure-data-replicaset 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-replicaset Reconfigure Successful 109s
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-replicaset
Name: mops-reconfigure-data-replicaset
Namespace: demo
Labels: <none>
Annotations: API Version: ops.kubedb.com/v1alpha1
Kind: MongoDBOpsRequest
Metadata:
Creation Timestamp: 2020-08-26T18:36:14Z
Finalizers:
kubedb.com
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:replicaSet:
.:
f:data:
.:
f:mongod.conf:
f:databaseRef:
.:
f:name:
f:type:
Manager: kubectl
Operation: Update
Time: 2020-08-26T18:36:14Z
API Version: ops.kubedb.com/v1alpha1
Fields Type: FieldsV1
fieldsV1:
f:metadata:
f:finalizers:
f:status:
.:
f:conditions:
f:observedGeneration:
f:phase:
Manager: kubedb-enterprise
Operation: Update
Time: 2020-08-26T18:37:55Z
Resource Version: 6291551
Self Link: /apis/ops.kubedb.com/v1alpha1/namespaces/demo/mongodbopsrequests/mops-reconfigure-data-replicaset
UID: 0e3a72d8-c906-48cb-bc0c-e87671367454
Spec:
Custom Config:
ReplicaSet:
Data:
mongod.conf: net:
maxIncomingConnections: 30000
Database Ref:
Name: mg-replicaset
Type: Reconfigure
Status:
Conditions:
Last Transition Time: 2020-08-26T18:36:14Z
Message: MongoDB ops request is being processed
Observed Generation: 1
Reason: Scaling
Status: True
Type: Scaling
Last Transition Time: 2020-08-26T18:37:55Z
Message: Successfully Reconfigured mongodb
Observed Generation: 1
Reason: ReconfigureReplicaset
Status: True
Type: ReconfigureReplicaset
Last Transition Time: 2020-08-26T18:37:55Z
Message: Succefully Resumed mongodb: mg-replicaset
Observed Generation: 1
Reason: ResumeDatabase
Status: True
Type: ResumeDatabase
Last Transition Time: 2020-08-26T18:37:55Z
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 ReconfigureReplicaset 25s KubeDB Enterprise Operator Successfully Reconfigured mongodb
Normal ResumeDatabase 25s KubeDB Enterprise Operator Resuming MongoDB
Normal ResumeDatabase 25s KubeDB Enterprise Operator Successfully Started Balancer
Normal Successful 25s KubeDB Enterprise Operator Successfully Reconfigured Database
Now let’s connect to a mongodb instance and run a mongodb internal command to check the new configuration we have provided.
$ kubectl exec -n demo mg-replicaset-0 -- mongo admin -u root -p nrKuxni0wDSMrgwy --eval "db._adminCommand( {getCmdLineOpts: 1})" --quiet
{
"argv" : [
"mongod",
"--dbpath=/data/db",
"--auth",
"--bind_ip=0.0.0.0",
"--port=27017",
"--sslMode=disabled",
"--replSet=replicaset",
"--keyFile=/data/configdb/key.txt",
"--clusterAuthMode=keyFile",
"--config=/data/configdb/mongod.conf"
],
"parsed" : {
"config" : "/data/configdb/mongod.conf",
"net" : {
"bindIp" : "0.0.0.0",
"maxIncomingConnections" : 30000,
"port" : 27017,
"ssl" : {
"mode" : "disabled"
}
},
"replication" : {
"replSet" : "replicaset"
},
"security" : {
"authorization" : "enabled",
"clusterAuthMode" : "keyFile",
"keyFile" : "/data/configdb/key.txt"
},
"storage" : {
"dbPath" : "/data/db"
}
},
"ok" : 1,
"operationTime" : Timestamp(1598467113, 1),
"$clusterTime" : {
"clusterTime" : Timestamp(1598467113, 1),
"signature" : {
"hash" : BinData(0,"jDOBwlqD1dG9mIKgTwX7K5NnJfs="),
"keyId" : NumberLong("6865318254139670530")
}
}
}
As we can see from the configuration of running mongodb, the value of maxIncomingConnections has been changed from 20000 to 30000. 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-replicaset
kubectl delete mongodbopsrequest -n demo mops-reconfigure-replicaset mops-reconfigure-data-replicaset