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Reconfigure MongoDB Shard
This guide will show you how to use KubeDB Ops-manager 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
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 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 4.4.26.
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 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/v1alpha2
kind: MongoDB
metadata:
name: mg-sharding
namespace: demo
spec:
version: 4.4.26
shardTopology:
configServer:
replicas: 3
configSecret:
name: mg-custom-config
storage:
resources:
requests:
storage: 1Gi
storageClassName: standard
mongos:
replicas: 2
configSecret:
name: mg-custom-config
shard:
replicas: 3
shards: 2
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/v2024.4.27/docs/examples/mongodb/reconfigure/mg-shard-config.yaml
mongodb.kubedb.com/mg-sharding created
Now, wait until mg-sharding has status Ready. i.e,
$ kubectl get mg -n demo
NAME VERSION STATUS AGE
mg-sharding 4.4.26 Ready 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
root
$ kubectl get secrets -n demo mg-sharding-auth -o jsonpath='{.data.\password}' | base64 -d
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" : "*",
"ipv6" : true,
"maxIncomingConnections" : 10000,
"port" : 27017,
"tls" : {
"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" : "*",
"ipv6" : true,
"maxIncomingConnections" : 10000,
"port" : 27017,
"tls" : {
"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" : "*",
"ipv6" : true,
"maxIncomingConnections" : 10000,
"port" : 27017,
"tls" : {
"mode" : "disabled"
}
}
As we can see from the configuration of ready mongodb, the value of maxIncomingConnections has been set to 10000 in all nodes.
Reconfigure using new 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-shard
namespace: demo
spec:
type: Reconfigure
databaseRef:
name: mg-sharding
configuration:
shard:
configSecret:
name: new-custom-config
configServer:
configSecret:
name: new-custom-config
mongos:
configSecret:
name: new-custom-config
readinessCriteria:
oplogMaxLagSeconds: 20
objectsCountDiffPercentage: 10
timeout: 5m
apply: IfReady
Here,
spec.databaseRef.namespecifies that we are reconfiguringmops-reconfigure-sharddatabase.spec.typespecifies that we are performingReconfigureon our database.spec.configuration.shard.configSecret.namespecifies the name of the new secret for shard nodes.spec.configuration.configServer.configSecret.namespecifies the name of the new secret for configServer nodes.spec.configuration.mongos.configSecret.namespecifies the name of the new secret for mongos nodes.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.
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/v2024.4.27/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 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-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
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 ready 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 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 data field in the MongoDBOpsRequest CR. The MongoDBOpsRequest yaml is given below,
apiVersion: ops.kubedb.com/v1alpha1
kind: MongoDBOpsRequest
metadata:
name: mops-reconfigure-apply-shard
namespace: demo
spec:
type: Reconfigure
databaseRef:
name: mg-sharding
configuration:
shard:
applyConfig:
mongod.conf: |-
net:
maxIncomingConnections: 30000
configServer:
applyConfig:
mongod.conf: |-
net:
maxIncomingConnections: 30000
mongos:
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-sharddatabase.spec.typespecifies that we are performingReconfigureon our database.spec.configuration.shard.applyConfigspecifies the new configuration that will be merged in the existing secret for shard nodes.spec.configuration.configServer.applyConfigspecifies the new configuration that will be merged in the existing secret for configServer nodes.spec.configuration.mongos.applyConfigspecifies the new configuration that will be merged in the existing secret for mongos nodes.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.
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/v2024.4.27/docs/examples/mongodb/reconfigure/mops-reconfigure-apply-shard.yaml
mongodbopsrequest.ops.kubedb.com/mops-reconfigure-apply-shard 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-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-apply-shard
Name: mops-reconfigure-apply-shard
Namespace: demo
Labels: <none>
Annotations: <none>
API Version: ops.kubedb.com/v1alpha1
Kind: MongoDBOpsRequest
Metadata:
Creation Timestamp: 2021-03-02T13:08:25Z
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:configServer:
.:
f:configSecret:
.:
f:name:
f:mongos:
.:
f:configSecret:
.:
f:name:
f:shard:
.:
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: 2021-03-02T13:08:25Z
API Version: ops.kubedb.com/v1alpha1
Fields Type: FieldsV1
fieldsV1:
f:spec:
f:configuration:
f:configServer:
f:podTemplate:
.:
f:controller:
f:metadata:
f:spec:
.:
f:resources:
f:mongos:
f:podTemplate:
.:
f:controller:
f:metadata:
f:spec:
.:
f:resources:
f:shard:
f:podTemplate:
.:
f:controller:
f:metadata:
f:spec:
.:
f:resources:
f:status:
.:
f:conditions:
f:observedGeneration:
f:phase:
Manager: kubedb-enterprise
Operation: Update
Time: 2021-03-02T13:08:25Z
Resource Version: 103635
Self Link: /apis/ops.kubedb.com/v1alpha1/namespaces/demo/mongodbopsrequests/mops-reconfigure-apply-shard
UID: ab454bcb-164c-4fa2-9eaa-dd47c60fe874
Spec:
Apply: IfReady
Configuration:
Config Server:
Apply Config: net:
maxIncomingConnections: 30000
Mongos:
Apply Config: net:
maxIncomingConnections: 30000
Shard:
Apply Config: net:
maxIncomingConnections: 30000
Database Ref:
Name: mg-sharding
Readiness Criteria:
Objects Count Diff Percentage: 10
Oplog Max Lag Seconds: 20
Timeout: 5m
Type: Reconfigure
Status:
Conditions:
Last Transition Time: 2021-03-02T13:08:25Z
Message: MongoDB ops request is reconfiguring database
Observed Generation: 1
Reason: Reconfigure
Status: True
Type: Reconfigure
Last Transition Time: 2021-03-02T13:10:10Z
Message: Successfully Reconfigured MongoDB
Observed Generation: 1
Reason: ReconfigureConfigServer
Status: True
Type: ReconfigureConfigServer
Last Transition Time: 2021-03-02T13:13:15Z
Message: Successfully Reconfigured MongoDB
Observed Generation: 1
Reason: ReconfigureShard
Status: True
Type: ReconfigureShard
Last Transition Time: 2021-03-02T13:14:10Z
Message: Successfully Reconfigured MongoDB
Observed Generation: 1
Reason: ReconfigureMongos
Status: True
Type: ReconfigureMongos
Last Transition Time: 2021-03-02T13:14:10Z
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 13m KubeDB Ops-manager operator Pausing MongoDB demo/mg-sharding
Normal PauseDatabase 13m KubeDB Ops-manager operator Successfully paused MongoDB demo/mg-sharding
Normal ReconfigureConfigServer 12m KubeDB Ops-manager operator Successfully Reconfigured MongoDB
Normal ReconfigureShard 9m7s KubeDB Ops-manager operator Successfully Reconfigured MongoDB
Normal ReconfigureMongos 8m12s KubeDB Ops-manager operator Successfully Reconfigured MongoDB
Normal ResumeDatabase 8m12s KubeDB Ops-manager operator Resuming MongoDB demo/mg-sharding
Normal ResumeDatabase 8m12s KubeDB Ops-manager operator Successfully resumed MongoDB demo/mg-sharding
Normal Successful 8m12s KubeDB Ops-manager 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" : "*",
"ipv6" : true,
"maxIncomingConnections" : 20000,
"port" : 27017,
"tls" : {
"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" : "*",
"ipv6" : true,
"maxIncomingConnections" : 20000,
"port" : 27017,
"tls" : {
"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" : "*",
"ipv6" : true,
"maxIncomingConnections" : 20000,
"port" : 27017,
"tls" : {
"mode" : "disabled"
}
}
As we can see from the configuration of ready 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-apply-shard