New to KubeDB? Please start here.
Reconfigure MongoDB Replicaset Database
This guide will show you how to use KubeDB Ops-manager 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
KubeDBProvisioner and Ops-manager 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 4.4.26.
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 secret with this configuration file.
$ kubectl create secret generic -n demo mg-custom-config --from-file=./mongod.conf
secret/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/v1
kind: MongoDB
metadata:
name: mg-replicaset
namespace: demo
spec:
version: "4.4.26"
replicas: 3
replicaSet:
name: rs0
storageType: Durable
storage:
storageClassName: "standard"
accessModes:
- ReadWriteOnce
resources:
requests:
storage: 1Gi
configSecret:
name: mg-custom-config
Let’s create the MongoDB CR we have shown above,
$ kubectl create -f https://github.com/kubedb/docs/raw/v2024.12.18/docs/examples/mongodb/reconfigure/mg-replicaset-config.yaml
mongodb.kubedb.com/mg-replicaset created
Now, wait until mg-replicaset has status Ready. i.e,
$ kubectl get mg -n demo
NAME VERSION STATUS AGE
mg-replicaset 4.4.26 Ready 19m
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
root
$ kubectl get secrets -n demo mg-replicaset-auth -o jsonpath='{.data.\password}' | base64 -d
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
{
"argv" : [
"mongod",
"--dbpath=/data/db",
"--auth",
"--ipv6",
"--bind_ip_all",
"--port=27017",
"--tlsMode=disabled",
"--replSet=rs0",
"--keyFile=/data/configdb/key.txt",
"--clusterAuthMode=keyFile",
"--config=/data/configdb/mongod.conf"
],
"parsed" : {
"config" : "/data/configdb/mongod.conf",
"net" : {
"bindIp" : "*",
"ipv6" : true,
"maxIncomingConnections" : 10000,
"port" : 27017,
"tls" : {
"mode" : "disabled"
}
},
"replication" : {
"replSet" : "rs0"
},
"security" : {
"authorization" : "enabled",
"clusterAuthMode" : "keyFile",
"keyFile" : "/data/configdb/key.txt"
},
"storage" : {
"dbPath" : "/data/db"
}
},
"ok" : 1,
"$clusterTime" : {
"clusterTime" : Timestamp(1614668500, 1),
"signature" : {
"hash" : BinData(0,"7sh886HhsNYajGxYGp5Jxi52IzA="),
"keyId" : NumberLong("6934943333319966722")
}
},
"operationTime" : Timestamp(1614668500, 1)
}
As we can see from the configuration of ready mongodb, the value of maxIncomingConnections has been set to 10000.
Reconfigure using new config secret
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 secret with this configuration file.
$ kubectl create secret generic -n demo new-custom-config --from-file=./mongod.conf
secret/new-custom-config created
Create MongoDBOpsRequest
Now, we will use this secret to replace the previous secret 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
configuration:
replicaSet:
configSecret:
name: new-custom-config
readinessCriteria:
oplogMaxLagSeconds: 20
objectsCountDiffPercentage: 10
timeout: 5m
apply: IfReady
Here,
spec.databaseRef.namespecifies that we are reconfiguringmops-reconfigure-replicasetdatabase.spec.typespecifies that we are performingReconfigureon our database.spec.customConfig.replicaSet.configSecret.namespecifies the name of the new secret.spec.customConfig.arbiter.configSecret.namecould also be specified with a config-secret.- Have a look here on the respective sections to understand the
readinessCriteria,timeout&applyfields.
Let’s create the MongoDBOpsRequest CR we have shown above,
$ kubectl apply -f https://github.com/kubedb/docs/raw/v2024.12.18/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 Ops-manager operator will update the configSecret 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: <none>
API Version: ops.kubedb.com/v1alpha1
Kind: MongoDBOpsRequest
Metadata:
Creation Timestamp: 2021-03-02T07:04:31Z
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:apply:
f:configuration:
.:
f:replicaSet:
.:
f:configSecret:
.:
f:name:
f:databaseRef:
.:
f:name:
f:readinessCriteria:
.:
f:objectsCountDiffPercentage:
f:oplogMaxLagSeconds:
f:timeout:
f:type:
Manager: kubectl-client-side-apply
Operation: Update
Time: 2021-03-02T07:04:31Z
API Version: ops.kubedb.com/v1alpha1
Fields Type: FieldsV1
fieldsV1:
f:spec:
f:configuration:
f:replicaSet:
f:podTemplate:
.:
f:controller:
f:metadata:
f:spec:
.:
f:resources:
f:status:
.:
f:conditions:
f:observedGeneration:
f:phase:
Manager: kubedb-enterprise
Operation: Update
Time: 2021-03-02T07:04:31Z
Resource Version: 29869
Self Link: /apis/ops.kubedb.com/v1alpha1/namespaces/demo/mongodbopsrequests/mops-reconfigure-replicaset
UID: 064733d6-19db-4153-82f7-bc0580116ee6
Spec:
Apply: IfReady
Configuration:
Replica Set:
Config Secret:
Name: new-custom-config
Database Ref:
Name: mg-replicaset
Readiness Criteria:
Objects Count Diff Percentage: 10
Oplog Max Lag Seconds: 20
Timeout: 5m
Type: Reconfigure
Status:
Conditions:
Last Transition Time: 2021-03-02T07:04:31Z
Message: MongoDB ops request is reconfiguring database
Observed Generation: 1
Reason: Reconfigure
Status: True
Type: Reconfigure
Last Transition Time: 2021-03-02T07:06:21Z
Message: Successfully Reconfigured MongoDB
Observed Generation: 1
Reason: ReconfigureReplicaset
Status: True
Type: ReconfigureReplicaset
Last Transition Time: 2021-03-02T07:06:21Z
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 PauseDatabase 2m55s KubeDB Ops-manager operator Pausing MongoDB demo/mg-replicaset
Normal PauseDatabase 2m55s KubeDB Ops-manager operator Successfully paused MongoDB demo/mg-replicaset
Normal ReconfigureReplicaset 65s KubeDB Ops-manager operator Successfully Reconfigured MongoDB
Normal ResumeDatabase 65s KubeDB Ops-manager operator Resuming MongoDB demo/mg-replicaset
Normal ResumeDatabase 65s KubeDB Ops-manager operator Successfully resumed MongoDB demo/mg-replicaset
Normal Successful 65s KubeDB Ops-manager 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",
"--ipv6",
"--bind_ip_all",
"--port=27017",
"--tlsMode=disabled",
"--replSet=rs0",
"--keyFile=/data/configdb/key.txt",
"--clusterAuthMode=keyFile",
"--config=/data/configdb/mongod.conf"
],
"parsed" : {
"config" : "/data/configdb/mongod.conf",
"net" : {
"bindIp" : "*",
"ipv6" : true,
"maxIncomingConnections" : 20000,
"port" : 27017,
"tls" : {
"mode" : "disabled"
}
},
"replication" : {
"replSet" : "rs0"
},
"security" : {
"authorization" : "enabled",
"clusterAuthMode" : "keyFile",
"keyFile" : "/data/configdb/key.txt"
},
"storage" : {
"dbPath" : "/data/db"
}
},
"ok" : 1,
"$clusterTime" : {
"clusterTime" : Timestamp(1614668887, 1),
"signature" : {
"hash" : BinData(0,"5q35Y51+YpbVHFKoaU7lUWi38oY="),
"keyId" : NumberLong("6934943333319966722")
}
},
"operationTime" : Timestamp(1614668887, 1)
}
As we can see from the configuration of ready mongodb, the value of maxIncomingConnections has been changed from 10000 to 20000. So the reconfiguration of the database is successful.
Reconfigure using apply config
Now we will reconfigure this database again to set maxIncomingConnections to 30000. This time we won’t use a new secret. We will use the applyConfig field of the MongoDBOpsRequest. This will merge the new config in the existing secret.
Create MongoDBOpsRequest
Now, we will use the new configuration in the applyConfig field in the MongoDBOpsRequest CR. The MongoDBOpsRequest yaml is given below,
apiVersion: ops.kubedb.com/v1alpha1
kind: MongoDBOpsRequest
metadata:
name: mops-reconfigure-apply-replicaset
namespace: demo
spec:
type: Reconfigure
databaseRef:
name: mg-replicaset
configuration:
replicaSet:
applyConfig:
mongod.conf: |-
net:
maxIncomingConnections: 30000
readinessCriteria:
oplogMaxLagSeconds: 20
objectsCountDiffPercentage: 10
timeout: 5m
apply: IfReady
Here,
spec.databaseRef.namespecifies that we are reconfiguringmops-reconfigure-apply-replicasetdatabase.spec.typespecifies that we are performingReconfigureon our database.spec.configuration.replicaSet.applyConfigspecifies the new configuration that will be merged in the existing secret.spec.customConfig.arbiter.configSecret.namecould also be specified with a config-secret.- Have a look here on the respective sections to understand the
readinessCriteria,timeout&applyfields.
Let’s create the MongoDBOpsRequest CR we have shown above,
$ kubectl apply -f https://github.com/kubedb/docs/raw/v2024.12.18/docs/examples/mongodb/reconfigure/mops-reconfigure-apply-replicaset.yaml
mongodbopsrequest.ops.kubedb.com/mops-reconfigure-apply-replicaset created
Verify the new configuration is working
If everything goes well, KubeDB Ops-manager 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-apply-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-apply-replicaset
Name: mops-reconfigure-apply-replicaset
Namespace: demo
Labels: <none>
Annotations: <none>
API Version: ops.kubedb.com/v1alpha1
Kind: MongoDBOpsRequest
Metadata:
Creation Timestamp: 2021-03-02T07:09:39Z
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:apply:
f:configuration:
.:
f:replicaSet:
.:
f:applyConfig:
f:databaseRef:
.:
f:name:
f:readinessCriteria:
.:
f:objectsCountDiffPercentage:
f:oplogMaxLagSeconds:
f:timeout:
f:type:
Manager: kubectl-client-side-apply
Operation: Update
Time: 2021-03-02T07:09:39Z
API Version: ops.kubedb.com/v1alpha1
Fields Type: FieldsV1
fieldsV1:
f:spec:
f:configuration:
f:replicaSet:
f:podTemplate:
.:
f:controller:
f:metadata:
f:spec:
.:
f:resources:
f:status:
.:
f:conditions:
f:observedGeneration:
f:phase:
Manager: kubedb-enterprise
Operation: Update
Time: 2021-03-02T07:09:39Z
Resource Version: 31005
Self Link: /apis/ops.kubedb.com/v1alpha1/namespaces/demo/mongodbopsrequests/mops-reconfigure-apply-replicaset
UID: 0137442b-1b04-43ed-8de7-ecd913b44065
Spec:
Apply: IfReady
Configuration:
Replica Set:
Apply Config: net:
maxIncomingConnections: 30000
Database Ref:
Name: mg-replicaset
Readiness Criteria:
Objects Count Diff Percentage: 10
Oplog Max Lag Seconds: 20
Timeout: 5m
Type: Reconfigure
Status:
Conditions:
Last Transition Time: 2021-03-02T07:09:39Z
Message: MongoDB ops request is reconfiguring database
Observed Generation: 1
Reason: Reconfigure
Status: True
Type: Reconfigure
Last Transition Time: 2021-03-02T07:11:14Z
Message: Successfully Reconfigured MongoDB
Observed Generation: 1
Reason: ReconfigureReplicaset
Status: True
Type: ReconfigureReplicaset
Last Transition Time: 2021-03-02T07:11:14Z
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 PauseDatabase 9m20s KubeDB Ops-manager operator Pausing MongoDB demo/mg-replicaset
Normal PauseDatabase 9m20s KubeDB Ops-manager operator Successfully paused MongoDB demo/mg-replicaset
Normal ReconfigureReplicaset 7m45s KubeDB Ops-manager operator Successfully Reconfigured MongoDB
Normal ResumeDatabase 7m45s KubeDB Ops-manager operator Resuming MongoDB demo/mg-replicaset
Normal ResumeDatabase 7m45s KubeDB Ops-manager operator Successfully resumed MongoDB demo/mg-replicaset
Normal Successful 7m45s KubeDB Ops-manager 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",
"--ipv6",
"--bind_ip_all",
"--port=27017",
"--tlsMode=disabled",
"--replSet=rs0",
"--keyFile=/data/configdb/key.txt",
"--clusterAuthMode=keyFile",
"--config=/data/configdb/mongod.conf"
],
"parsed" : {
"config" : "/data/configdb/mongod.conf",
"net" : {
"bindIp" : "*",
"ipv6" : true,
"maxIncomingConnections" : 30000,
"port" : 27017,
"tls" : {
"mode" : "disabled"
}
},
"replication" : {
"replSet" : "rs0"
},
"security" : {
"authorization" : "enabled",
"clusterAuthMode" : "keyFile",
"keyFile" : "/data/configdb/key.txt"
},
"storage" : {
"dbPath" : "/data/db"
}
},
"ok" : 1,
"$clusterTime" : {
"clusterTime" : Timestamp(1614669580, 1),
"signature" : {
"hash" : BinData(0,"u/xTAa4aW/8bsRvBYPffwQCeTF0="),
"keyId" : NumberLong("6934943333319966722")
}
},
"operationTime" : Timestamp(1614669580, 1)
}
As we can see from the configuration of ready mongodb, the value of maxIncomingConnections has been changed from 20000 to 30000. So the reconfiguration of the database using the applyConfig 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-apply-replicaset