New to KubeDB? Please start here.

MongoDB Sharding

This tutorial will show you how to use KubeDB to run a sharded MongoDB cluster.

Before You Begin

Before proceeding:

  • Read mongodb sharding concept to learn about MongoDB Sharding clustering.

  • 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 Minikube.

  • Now, install KubeDB cli on your workstation and KubeDB operator in your cluster following the steps here.

  • To keep things isolated, this tutorial uses a separate namespace called demo throughout this tutorial. Run the following command to prepare your cluster for this tutorial:

    $ kubectl create ns demo
    namespace/demo created
    

Note: The yaml files used in this tutorial are stored in docs/examples/mongodb folder in GitHub repository kubedb/cli.

Deploy Sharded MongoDB Cluster

To deploy a MongoDB Sharding, user have to specify spec.replicaSet option in Mongodb CRD.

The following is an example of a Mongodb object which creates MongoDB Sharding of three members.

apiVersion: kubedb.com/v1alpha1
kind: MongoDB
metadata:
  name: mongo-sh
  namespace: demo
spec:
  version: 3.6-v3
  shardTopology:
    configServer:
      replicas: 3
      storage:
        resources:
          requests:
            storage: 1Gi
        storageClassName: standard
    mongos:
      replicas: 2
      strategy:
        type: RollingUpdate
    shard:
      replicas: 3
      shards: 3
      storage:
        resources:
          requests:
            storage: 1Gi
        storageClassName: standard
$ kubectl create -f https://raw.githubusercontent.com/kubedb/cli/0.12.0//docs/examples/mongodb/clustering/mongo-sharding.yaml
mongodb.kubedb.com/mongo-sh created

Here,

  • spec.shardTopology represents the topology configuration for sharding.
    • shard represents configuration for Shard component of mongodb.
    • shards represents number of shards for a mongodb deployment. Each shard is deployed as a replicaset.
    • replicas represents number of replicas of each shard replicaset.
    • prefix represents the prefix of each shard node.
    • configSource is an optional field to provide custom configuration file for shards (i.e mongod.cnf). If specified, this file will be used as configuration file otherwise a default configuration file will be used.
    • podTemplate is an optional configuration for pods.
    • storage to specify pvc spec for each node of sharding. You can specify any StorageClass available in your cluster with appropriate resource requests.
    • configServer represents configuration for ConfigServer component of mongodb.
    • replicas represents number of replicas for configServer replicaset. Here, configServer is deployed as a replicaset of mongodb.
    • prefix represents the prefix of configServer nodes.
    • configSource is an optional field to provide custom configuration file for configSource (i.e mongod.cnf). If specified, this file will be used as configuration file otherwise a default configuration file will be used.
    • podTemplate is an optional configuration for pods.
    • storage to specify pvc spec for each node of configServer. You can specify any StorageClass available in your cluster with appropriate resource requests.
    • mongos represents configuration for Mongos component of mongodb. Mongos instances run as stateless components (deployment).
    • replicas represents number of replicas of Mongos instance. Here, Mongos is not deployed as replicaset.
    • prefix represents the prefix of mongos nodes.
    • configSource is an optional field to provide custom configuration file for mongos (i.e mongod.cnf). If specified, this file will be used as configuration file otherwise a default configuration file will be used.
    • podTemplate is an optional configuration for pods.
    • strategy is the deployment strategy to use to replace existing pods with new ones. This is optional. If not provided, kubernetes will use default deploymentStrategy, ie. RollingUpdate. See more about Deployment Strategy.
  • spec.certificateSecret (optional) is a secret name that contains keyfile(a random string) against key.txt key. Each mongod replica set instances in the topology uses the contents of the keyfile as the shared password for authenticating other members in the replicaset. Only mongod instances with the correct keyfile can join the replica set. User can provide the CertificateSecret by creating a secret with key key.txt. See here to create the string for CertificateSecret. If CertificateSecret is not given, KubeDB operator will generate a CertificateSecret itself.

KubeDB operator watches for MongoDB objects using Kubernetes api. When a MongoDB object is created, KubeDB operator will create a new StatefulSet and a ClusterIP Service with the matching MongoDB object name. KubeDB operator will also create governing services for StatefulSets with the name <mongodb-name>-<node-type>-gvr. No MongoDB specific RBAC permission is required in RBAC enabled clusters.

MongoDB mongo-sh state,

$ kubectl get mg -n demo
NAME       VERSION   STATUS    AGE
mongo-sh   3.6-v3    Running   9m41s

Sharding and ConfigServer nodes are deployed as statefulset.

$ kubectl get statefulset -n demo
NAME                 READY   AGE
mongo-sh-configsvr   3/3     11m
mongo-sh-shard0      3/3     10m
mongo-sh-shard1      3/3     8m59s
mongo-sh-shard2      3/3     7m45s

Mongos nodes are deployed as deployment.

$ kubectl get deployments -n demo
NAME              READY   UP-TO-DATE   AVAILABLE   AGE
mongo-sh-mongos   2/2     2            2           8m41s

All PVCs and PVs for MongoDB mongo-sh,

$ kubectl get pvc -n demo
NAME                           STATUS   VOLUME                                     CAPACITY   ACCESS MODES   STORAGECLASS   AGE
datadir-mongo-sh-configsvr-0   Bound    pvc-1db4185e-6a5f-11e9-a871-080027a851ba   1Gi        RWO            standard       16m
datadir-mongo-sh-configsvr-1   Bound    pvc-330cc6ee-6a5f-11e9-a871-080027a851ba   1Gi        RWO            standard       16m
datadir-mongo-sh-configsvr-2   Bound    pvc-3db2d3f5-6a5f-11e9-a871-080027a851ba   1Gi        RWO            standard       15m
datadir-mongo-sh-shard0-0      Bound    pvc-49b7cc3b-6a5f-11e9-a871-080027a851ba   1Gi        RWO            standard       15m
datadir-mongo-sh-shard0-1      Bound    pvc-5b781770-6a5f-11e9-a871-080027a851ba   1Gi        RWO            standard       15m
datadir-mongo-sh-shard0-2      Bound    pvc-6ba3263e-6a5f-11e9-a871-080027a851ba   1Gi        RWO            standard       14m
datadir-mongo-sh-shard1-0      Bound    pvc-75feb227-6a5f-11e9-a871-080027a851ba   1Gi        RWO            standard       14m
datadir-mongo-sh-shard1-1      Bound    pvc-89bb7bb3-6a5f-11e9-a871-080027a851ba   1Gi        RWO            standard       13m
datadir-mongo-sh-shard1-2      Bound    pvc-98c96ae4-6a5f-11e9-a871-080027a851ba   1Gi        RWO            standard       13m
datadir-mongo-sh-shard2-0      Bound    pvc-a1eebcd2-6a5f-11e9-a871-080027a851ba   1Gi        RWO            standard       13m
datadir-mongo-sh-shard2-1      Bound    pvc-b231fb18-6a5f-11e9-a871-080027a851ba   1Gi        RWO            standard       12m
datadir-mongo-sh-shard2-2      Bound    pvc-c5bb265f-6a5f-11e9-a871-080027a851ba   1Gi        RWO            standard       12m


$ kubectl get pv -n demo
NAME                                       CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS   CLAIM                               STORAGECLASS   REASON   AGE
pvc-1db4185e-6a5f-11e9-a871-080027a851ba   1Gi        RWO            Delete           Bound    demo/datadir-mongo-sh-configsvr-0   standard                17m
pvc-330cc6ee-6a5f-11e9-a871-080027a851ba   1Gi        RWO            Delete           Bound    demo/datadir-mongo-sh-configsvr-1   standard                16m
pvc-3db2d3f5-6a5f-11e9-a871-080027a851ba   1Gi        RWO            Delete           Bound    demo/datadir-mongo-sh-configsvr-2   standard                16m
pvc-49b7cc3b-6a5f-11e9-a871-080027a851ba   1Gi        RWO            Delete           Bound    demo/datadir-mongo-sh-shard0-0      standard                16m
pvc-5b781770-6a5f-11e9-a871-080027a851ba   1Gi        RWO            Delete           Bound    demo/datadir-mongo-sh-shard0-1      standard                15m
pvc-6ba3263e-6a5f-11e9-a871-080027a851ba   1Gi        RWO            Delete           Bound    demo/datadir-mongo-sh-shard0-2      standard                15m
pvc-75feb227-6a5f-11e9-a871-080027a851ba   1Gi        RWO            Delete           Bound    demo/datadir-mongo-sh-shard1-0      standard                14m
pvc-89bb7bb3-6a5f-11e9-a871-080027a851ba   1Gi        RWO            Delete           Bound    demo/datadir-mongo-sh-shard1-1      standard                14m
pvc-98c96ae4-6a5f-11e9-a871-080027a851ba   1Gi        RWO            Delete           Bound    demo/datadir-mongo-sh-shard1-2      standard                13m
pvc-a1eebcd2-6a5f-11e9-a871-080027a851ba   1Gi        RWO            Delete           Bound    demo/datadir-mongo-sh-shard2-0      standard                13m
pvc-b231fb18-6a5f-11e9-a871-080027a851ba   1Gi        RWO            Delete           Bound    demo/datadir-mongo-sh-shard2-1      standard                13m
pvc-c5bb265f-6a5f-11e9-a871-080027a851ba   1Gi        RWO            Delete           Bound    demo/datadir-mongo-sh-shard2-2      standard                12m

Services created for MongoDB mongo-sh

$ kubectl get svc -n demo
NAME                     TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)     AGE
mongo-sh                 ClusterIP   10.108.188.201   <none>        27017/TCP   18m
mongo-sh-configsvr-gvr   ClusterIP   None             <none>        27017/TCP   18m
mongo-sh-shard0-gvr      ClusterIP   None             <none>        27017/TCP   18m
mongo-sh-shard1-gvr      ClusterIP   None             <none>        27017/TCP   18m
mongo-sh-shard2-gvr      ClusterIP   None             <none>        27017/TCP   18m

KubeDB operator sets the status.phase to Running once the database is successfully created. It has also defaulted some field of crd object. Run the following command to see the modified MongoDB object:

$ kubedb get mg -n demo mongo-sh -o yaml
apiVersion: kubedb.com/v1alpha1
kind: MongoDB
metadata:
  creationTimestamp: "2019-04-29T09:13:56Z"
  finalizers:
  - kubedb.com
  generation: 3
  name: mongo-sh
  namespace: demo
  resourceVersion: "25825"
  selfLink: /apis/kubedb.com/v1alpha1/namespaces/demo/mongodbs/mongo-sh
  uid: 1d83622c-6a5f-11e9-a871-080027a851ba
spec:
  certificateSecret:
    secretName: mongo-sh-keyfile
  databaseSecret:
    secretName: mongo-sh-auth
  serviceTemplate:
    metadata: {}
    spec: {}
  shardTopology:
    configServer:
      podTemplate:
        controller: {}
        metadata: {}
        spec:
          livenessProbe:
            exec:
              command:
              - mongo
              - --eval
              - db.adminCommand('ping')
            failureThreshold: 3
            periodSeconds: 10
            successThreshold: 1
            timeoutSeconds: 5
          readinessProbe:
            exec:
              command:
              - mongo
              - --eval
              - db.adminCommand('ping')
            failureThreshold: 3
            periodSeconds: 10
            successThreshold: 1
            timeoutSeconds: 1
          resources: {}
          securityContext:
            fsGroup: 999
            runAsNonRoot: true
            runAsUser: 999
      replicas: 3
      storage:
        dataSource: null
        resources:
          requests:
            storage: 1Gi
        storageClassName: standard
    mongos:
      podTemplate:
        controller: {}
        metadata: {}
        spec:
          livenessProbe:
            exec:
              command:
              - mongo
              - --eval
              - db.adminCommand('ping')
            failureThreshold: 3
            periodSeconds: 10
            successThreshold: 1
            timeoutSeconds: 5
          readinessProbe:
            exec:
              command:
              - mongo
              - --eval
              - db.adminCommand('ping')
            failureThreshold: 3
            periodSeconds: 10
            successThreshold: 1
            timeoutSeconds: 1
          resources: {}
          securityContext:
            fsGroup: 999
            runAsNonRoot: true
            runAsUser: 999
      replicas: 2
      strategy:
        type: RollingUpdate
    shard:
      podTemplate:
        controller: {}
        metadata: {}
        spec:
          livenessProbe:
            exec:
              command:
              - mongo
              - --eval
              - db.adminCommand('ping')
            failureThreshold: 3
            periodSeconds: 10
            successThreshold: 1
            timeoutSeconds: 5
          readinessProbe:
            exec:
              command:
              - mongo
              - --eval
              - db.adminCommand('ping')
            failureThreshold: 3
            periodSeconds: 10
            successThreshold: 1
            timeoutSeconds: 1
          resources: {}
          securityContext:
            fsGroup: 999
            runAsNonRoot: true
            runAsUser: 999
      replicas: 3
      shards: 3
      storage:
        dataSource: null
        resources:
          requests:
            storage: 1Gi
        storageClassName: standard
  storageType: Durable
  terminationPolicy: Pause
  updateStrategy:
    type: RollingUpdate
  version: 3.6-v3
status:
  observedGeneration: 3$4212299729528774793
  phase: Running

Please note that KubeDB operator has created a new Secret called mongo-sh-auth (format: {mongodb-object-name}-auth) for storing the password for mongodb superuser. This secret contains a username key which contains the username for MongoDB superuser and a password key which contains the password for MongoDB superuser.

If you want to use custom or existing secret please specify that when creating the MongoDB object using spec.databaseSecret.secretName. While creating this secret manually, make sure the secret contains these two keys containing data username and password. For more details, please see here.

Connection Information

  • Hostname/address: you can use any of these
    • Service: mongo-sh.demo
    • Pod IP: ($ kubectl get po -n demo -l mongodb.kubedb.com/node.mongos=mongo-sh-mongos -o yaml | grep podIP)
  • Port: 27017
  • Username: Run following command to get username,

    $ kubectl get secrets -n demo mongo-sh-auth -o jsonpath='{.data.\username}' | base64 -d
    root
    
  • Password: Run the following command to get password,

    $ kubectl get secrets -n demo mongo-sh-auth -o jsonpath='{.data.\password}' | base64 -d
    7QiqLcuSCmZ8PU5a
    

Now, you can connect to this database through mongo-shell.

Sharded Data

In this tutorial, we will insert sharded and unsharded document, and we will see if the data actually sharded across cluster or not.

$ kubectl get po -n demo -l mongodb.kubedb.com/node.mongos=mongo-sh-mongos
NAME                               READY   STATUS    RESTARTS   AGE
mongo-sh-mongos-69b557f9f5-2kz68   1/1     Running   0          49m
mongo-sh-mongos-69b557f9f5-5hvh2   1/1     Running   0          49m

$ kubectl exec -it mongo-sh-mongos-69b557f9f5-2kz68 -n demo bash

mongodb@mongo-sh-mongos-69b557f9f5-2kz68:/$ mongo admin -u root -p 7QiqLcuSCmZ8PU5a
MongoDB shell version v3.6.12
connecting to: mongodb://127.0.0.1:27017/admin?gssapiServiceName=mongodb
Implicit session: session { "id" : UUID("8b7abf57-09e4-4e30-b4a0-a37ebf065e8f") }
MongoDB server version: 3.6.12
Welcome to the MongoDB shell.
For interactive help, type "help".
For more comprehensive documentation, see
	http://docs.mongodb.org/
Questions? Try the support group
	http://groups.google.com/group/mongodb-user
2019-04-29T10:09:17.311+0000 I STORAGE  [main] In File::open(), ::open for '/home/mongodb/.mongorc.js' failed with No such file or directory
mongos> isMaster;
2019-04-29T10:11:16.128+0000 E QUERY    [thread1] ReferenceError: isMaster is not defined :
@(shell):1:1
mongos> isMaster();
2019-04-29T10:11:20.020+0000 E QUERY    [thread1] ReferenceError: isMaster is not defined :
@(shell):1:1

mongos>

To detect if the MongoDB instance that your client is connected to is mongos, use the isMaster command. When a client connects to a mongos, isMaster returns a document with a msg field that holds the string isdbgrid.

mongos> rs.isMaster()
{
	"ismaster" : true,
	"msg" : "isdbgrid",
	"maxBsonObjectSize" : 16777216,
	"maxMessageSizeBytes" : 48000000,
	"maxWriteBatchSize" : 100000,
	"localTime" : ISODate("2019-04-29T10:12:00.145Z"),
	"logicalSessionTimeoutMinutes" : 30,
	"maxWireVersion" : 6,
	"minWireVersion" : 0,
	"ok" : 1,
	"operationTime" : Timestamp(1556532710, 1),
	"$clusterTime" : {
		"clusterTime" : Timestamp(1556532710, 1),
		"signature" : {
			"hash" : BinData(0,"6W7pmWBdVSzY0x+BxQj74d0WhXg="),
			"keyId" : NumberLong("6685242219722440730")
		}
	}
}

mongo-sh Shard status,

mongos> sh.status()
--- Sharding Status ---
  sharding version: {
  	"_id" : 1,
  	"minCompatibleVersion" : 5,
  	"currentVersion" : 6,
  	"clusterId" : ObjectId("5cc6c061f439d076e04d737b")
  }
  shards:
        {  "_id" : "shard0",  "host" : "shard0/mongo-sh-shard0-0.mongo-sh-shard0-gvr.demo.svc.cluster.local:27017,mongo-sh-shard0-1.mongo-sh-shard0-gvr.demo.svc.cluster.local:27017,mongo-sh-shard0-2.mongo-sh-shard0-gvr.demo.svc.cluster.local:27017",  "state" : 1 }
        {  "_id" : "shard1",  "host" : "shard1/mongo-sh-shard1-0.mongo-sh-shard1-gvr.demo.svc.cluster.local:27017,mongo-sh-shard1-1.mongo-sh-shard1-gvr.demo.svc.cluster.local:27017,mongo-sh-shard1-2.mongo-sh-shard1-gvr.demo.svc.cluster.local:27017",  "state" : 1 }
        {  "_id" : "shard2",  "host" : "shard2/mongo-sh-shard2-0.mongo-sh-shard2-gvr.demo.svc.cluster.local:27017,mongo-sh-shard2-1.mongo-sh-shard2-gvr.demo.svc.cluster.local:27017,mongo-sh-shard2-2.mongo-sh-shard2-gvr.demo.svc.cluster.local:27017",  "state" : 1 }
  active mongoses:
        "3.6.12" : 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)

Shard collection test.testcoll and insert document. See sh.shardCollection(namespace, key, unique, options) for details about shardCollection command.

mongos> sh.enableSharding("test");
{
	"ok" : 1,
	"operationTime" : Timestamp(1556535000, 8),
	"$clusterTime" : {
		"clusterTime" : Timestamp(1556535000, 8),
		"signature" : {
			"hash" : BinData(0,"84KefOzN8tKmsPfr6IrnBUxF9NM="),
			"keyId" : NumberLong("6685242219722440730")
		}
	}
}

mongos> sh.shardCollection("test.testcoll", {"myfield": 1});
{
	"collectionsharded" : "test.testcoll",
	"collectionUUID" : UUID("68ff9452-40bb-41a2-b35a-405132f90cd3"),
	"ok" : 1,
	"operationTime" : Timestamp(1556535010, 8),
	"$clusterTime" : {
		"clusterTime" : Timestamp(1556535010, 8),
		"signature" : {
			"hash" : BinData(0,"IgVzMa8qE4UBzjc2gOZJX5kZ3T4="),
			"keyId" : NumberLong("6685242219722440730")
		}
	}
}

mongos> use test;
switched to db test

mongos> db.testcoll.insert({"myfield": "a", "otherfield": "b"});
WriteResult({ "nInserted" : 1 })

mongos> db.testcoll.insert({"myfield": "c", "otherfield": "d", "kube" : "db" });
WriteResult({ "nInserted" : 1 })

mongos> db.testcoll.find();
{ "_id" : ObjectId("5cc6d6f656a9ddd30be2c12a"), "myfield" : "a", "otherfield" : "b" }
{ "_id" : ObjectId("5cc6d71e56a9ddd30be2c12b"), "myfield" : "c", "otherfield" : "d", "kube" : "db" }

Run sh.status() to see whether the test database has sharding enabled, and the primary shard for the test database.

The Sharded Collection section sh.status.databases.<collection> provides information on the sharding details for sharded collection(s) (E.g. test.testcoll). For each sharded collection, the section displays the shard key, the number of chunks per shard(s), the distribution of documents across chunks, and the tag information, if any, for shard key range(s).

mongos> sh.status();
--- Sharding Status ---
  sharding version: {
  	"_id" : 1,
  	"minCompatibleVersion" : 5,
  	"currentVersion" : 6,
  	"clusterId" : ObjectId("5cc6c061f439d076e04d737b")
  }
  shards:
        {  "_id" : "shard0",  "host" : "shard0/mongo-sh-shard0-0.mongo-sh-shard0-gvr.demo.svc.cluster.local:27017,mongo-sh-shard0-1.mongo-sh-shard0-gvr.demo.svc.cluster.local:27017,mongo-sh-shard0-2.mongo-sh-shard0-gvr.demo.svc.cluster.local:27017",  "state" : 1 }
        {  "_id" : "shard1",  "host" : "shard1/mongo-sh-shard1-0.mongo-sh-shard1-gvr.demo.svc.cluster.local:27017,mongo-sh-shard1-1.mongo-sh-shard1-gvr.demo.svc.cluster.local:27017,mongo-sh-shard1-2.mongo-sh-shard1-gvr.demo.svc.cluster.local:27017",  "state" : 1 }
        {  "_id" : "shard2",  "host" : "shard2/mongo-sh-shard2-0.mongo-sh-shard2-gvr.demo.svc.cluster.local:27017,mongo-sh-shard2-1.mongo-sh-shard2-gvr.demo.svc.cluster.local:27017,mongo-sh-shard2-2.mongo-sh-shard2-gvr.demo.svc.cluster.local:27017",  "state" : 1 }
  active mongoses:
        "3.6.12" : 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)
        {  "_id" : "test",  "primary" : "shard1",  "partitioned" : true }
                test.testcoll
                        shard key: { "myfield" : 1 }
                        unique: false
                        balancing: true
                        chunks:
                                shard1	1
                        { "myfield" : { "$minKey" : 1 } } -->> { "myfield" : { "$maxKey" : 1 } } on : shard1 Timestamp(1, 0)

Now create another database where partiotioned is not applied and see how the data is stored.

mongos> use demo
switched to db demo

mongos> db.testcoll2.insert({"myfield": "ccc", "otherfield": "d", "kube" : "db" });
WriteResult({ "nInserted" : 1 })

mongos> db.testcoll2.insert({"myfield": "aaa", "otherfield": "d", "kube" : "db" });
WriteResult({ "nInserted" : 1 })


mongos> db.testcoll2.find()
{ "_id" : ObjectId("5cc6dc831b6d9b3cddc947ec"), "myfield" : "ccc", "otherfield" : "d", "kube" : "db" }
{ "_id" : ObjectId("5cc6dce71b6d9b3cddc947ed"), "myfield" : "aaa", "otherfield" : "d", "kube" : "db" }

Now, eventually sh.status()

mongos> sh.status()
--- Sharding Status ---
  sharding version: {
  	"_id" : 1,
  	"minCompatibleVersion" : 5,
  	"currentVersion" : 6,
  	"clusterId" : ObjectId("5cc6c061f439d076e04d737b")
  }
  shards:
        {  "_id" : "shard0",  "host" : "shard0/mongo-sh-shard0-0.mongo-sh-shard0-gvr.demo.svc.cluster.local:27017,mongo-sh-shard0-1.mongo-sh-shard0-gvr.demo.svc.cluster.local:27017,mongo-sh-shard0-2.mongo-sh-shard0-gvr.demo.svc.cluster.local:27017",  "state" : 1 }
        {  "_id" : "shard1",  "host" : "shard1/mongo-sh-shard1-0.mongo-sh-shard1-gvr.demo.svc.cluster.local:27017,mongo-sh-shard1-1.mongo-sh-shard1-gvr.demo.svc.cluster.local:27017,mongo-sh-shard1-2.mongo-sh-shard1-gvr.demo.svc.cluster.local:27017",  "state" : 1 }
        {  "_id" : "shard2",  "host" : "shard2/mongo-sh-shard2-0.mongo-sh-shard2-gvr.demo.svc.cluster.local:27017,mongo-sh-shard2-1.mongo-sh-shard2-gvr.demo.svc.cluster.local:27017,mongo-sh-shard2-2.mongo-sh-shard2-gvr.demo.svc.cluster.local:27017",  "state" : 1 }
  active mongoses:
        "3.6.12" : 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)
        {  "_id" : "demo",  "primary" : "shard2",  "partitioned" : false }
        {  "_id" : "test",  "primary" : "shard1",  "partitioned" : true }
                test.testcoll
                        shard key: { "myfield" : 1 }
                        unique: false
                        balancing: true
                        chunks:
                                shard1	1
                        { "myfield" : { "$minKey" : 1 } } -->> { "myfield" : { "$maxKey" : 1 } } on : shard1 Timestamp(1, 0)

Here, demo database is not partitioned and all collections under demo database are stored in it’s primary shard, which is shard2.

Update number of ShardTopology Instances

User can increase or decrease the number of router/mongos spec.shardTopology.mongos.replicas.

At this moment, decreasing the number of shards and replicasets is not handled from KubeDB end. But, User can increase the number of instances if needed.

Here a table of allowed actions are given for mongodb ShardTopology,

InstancesIncreaseDecrease
# of replicas of Mongos spec.shardTopology.mongos.replicas
# of Shards spec.shardTopology.shard.shards
# of replicaset of each Shard spec.shardTopology.shard.replicas
# of replicaset of ConfigServer spec.shardTopology.configServer.replicas

Now edit MongoDB mongo-sh to increase spec.shardTopology.shard.shards to 4 and increase spec.shardTopology.mongos to 3.

$ kubectl edit mg -n demo mongo-sh
apiVersion: kubedb.com/v1alpha1
kind: MongoDB
metadata:
  name: mongo-sh
  namespace: demo
  ...
spec:
  shardTopology:
    mongos:
      replicas: 3 # set 3
      ...
    shard:
      shards: 4 # set 4
      ...
  ...

Watch for pod changes,

$ kubectl get po --all-namespaces -w
NAMESPACE     NAME                                    READY   STATUS    RESTARTS   AGE
demo          mongo-sh-configsvr-0                    1/1     Running   0          8m12s
demo          mongo-sh-configsvr-1                    1/1     Running   0          7m41s
demo          mongo-sh-configsvr-2                    1/1     Running   0          7m17s
demo          mongo-sh-mongos-69b557f9f5-2qvb7        1/1     Running   0          3m44s
demo          mongo-sh-mongos-69b557f9f5-6z2s4        1/1     Running   0          3m44s
demo          mongo-sh-shard0-0                       1/1     Running   0          7m4s
demo          mongo-sh-shard0-1                       1/1     Running   0          6m37s
demo          mongo-sh-shard0-2                       1/1     Running   0          6m20s
demo          mongo-sh-shard1-0                       1/1     Running   0          5m55s
demo          mongo-sh-shard1-1                       1/1     Running   0          5m29s
demo          mongo-sh-shard1-2                       1/1     Running   0          5m14s
demo          mongo-sh-shard2-0                       1/1     Running   0          4m59s
demo          mongo-sh-shard2-1                       1/1     Running   0          4m32s
demo          mongo-sh-shard2-2                       1/1     Running   0          4m11s
kube-system   coredns-fb8b8dccf-nzb5q                 1/1     Running   1          165m
kube-system   coredns-fb8b8dccf-tqldv                 1/1     Running   1          165m
kube-system   etcd-minikube                           1/1     Running   0          164m
kube-system   kube-addon-manager-minikube             1/1     Running   0          164m
kube-system   kube-apiserver-minikube                 1/1     Running   0          163m
kube-system   kube-controller-manager-minikube        1/1     Running   0          164m
kube-system   kube-proxy-qznbv                        1/1     Running   0          165m
kube-system   kube-scheduler-minikube                 1/1     Running   0          163m
kube-system   kubedb-operator-c8cd5c69-c5nkc          1/1     Running   0          44m
kube-system   kubernetes-dashboard-79dd6bfc48-l88rk   1/1     Running   4          165m
kube-system   storage-provisioner                     1/1     Running   0          164m
demo          mongo-sh-shard3-0                       0/1     Pending   0          0s
demo          mongo-sh-shard3-0                       0/1     Pending   0          0s
demo          mongo-sh-shard3-0                       0/1     Pending   0          9s
demo          mongo-sh-shard3-0                       0/1     Init:0/2   0          9s
demo          mongo-sh-shard3-0                       0/1     Init:1/2   0          10s
demo          mongo-sh-shard3-0                       0/1     Init:1/2   0          11s
demo          mongo-sh-shard3-0                       0/1     PodInitializing   0          30s
demo          mongo-sh-shard3-0                       0/1     Running           0          31s
demo          mongo-sh-shard3-0                       1/1     Running           0          41s
demo          mongo-sh-shard3-1                       0/1     Pending           0          0s
demo          mongo-sh-shard3-1                       0/1     Pending           0          0s
demo          mongo-sh-shard3-1                       0/1     Pending           0          5s
demo          mongo-sh-shard3-1                       0/1     Init:0/2          0          5s
demo          mongo-sh-shard3-1                       0/1     Init:1/2          0          6s
demo          mongo-sh-shard3-1                       0/1     Init:1/2          0          7s
demo          mongo-sh-shard3-1                       0/1     PodInitializing   0          15s
demo          mongo-sh-shard3-1                       0/1     Running           0          16s
demo          mongo-sh-shard3-1                       1/1     Running           0          23s
demo          mongo-sh-shard3-2                       0/1     Pending           0          0s
demo          mongo-sh-shard3-2                       0/1     Pending           0          0s
demo          mongo-sh-shard3-2                       0/1     Pending           0          2s
demo          mongo-sh-shard3-2                       0/1     Init:0/2          0          2s
demo          mongo-sh-shard3-2                       0/1     Init:1/2          0          4s
demo          mongo-sh-shard3-2                       0/1     Init:1/2          0          5s
demo          mongo-sh-shard3-2                       0/1     PodInitializing   0          14s
demo          mongo-sh-shard3-2                       0/1     Running           0          15s
demo          mongo-sh-shard3-2                       1/1     Running           0          22s
demo          mongo-sh-mongos-69b557f9f5-w77cs        0/1     Pending           0          0s
demo          mongo-sh-mongos-69b557f9f5-w77cs        0/1     Pending           0          0s
demo          mongo-sh-mongos-69b557f9f5-w77cs        0/1     Init:0/2          0          0s
demo          mongo-sh-mongos-598658d8f9-6j544        0/1     Pending           0          0s
demo          mongo-sh-mongos-598658d8f9-6j544        0/1     Pending           0          0s
demo          mongo-sh-mongos-598658d8f9-6j544        0/1     Init:0/2          0          0s
demo          mongo-sh-mongos-69b557f9f5-w77cs        0/1     Init:0/2          0          1s
demo          mongo-sh-mongos-69b557f9f5-w77cs        0/1     Init:1/2          0          3s
demo          mongo-sh-mongos-598658d8f9-6j544        0/1     Init:1/2          0          3s
demo          mongo-sh-mongos-598658d8f9-6j544        0/1     Init:1/2          0          4s
demo          mongo-sh-mongos-69b557f9f5-w77cs        0/1     Init:1/2          0          4s
demo          mongo-sh-mongos-69b557f9f5-w77cs        0/1     PodInitializing   0          7s
demo          mongo-sh-mongos-69b557f9f5-w77cs        0/1     Running           0          8s
demo          mongo-sh-mongos-598658d8f9-6j544        0/1     PodInitializing   0          8s
demo          mongo-sh-mongos-598658d8f9-6j544        0/1     Running           0          9s
demo          mongo-sh-mongos-598658d8f9-6j544        1/1     Running           0          12s
demo          mongo-sh-mongos-69b557f9f5-w77cs        0/1     Terminating       0          12s
demo          mongo-sh-mongos-598658d8f9-tmwvb        0/1     Pending           0          0s
demo          mongo-sh-mongos-598658d8f9-tmwvb        0/1     Pending           0          1s
demo          mongo-sh-mongos-598658d8f9-tmwvb        0/1     Init:0/2          0          1s
demo          mongo-sh-mongos-598658d8f9-tmwvb        0/1     Init:1/2          0          3s
demo          mongo-sh-mongos-69b557f9f5-w77cs        0/1     Terminating       0          15s
demo          mongo-sh-mongos-598658d8f9-tmwvb        0/1     Init:1/2          0          4s
demo          mongo-sh-mongos-69b557f9f5-w77cs        0/1     Terminating       0          19s
demo          mongo-sh-mongos-69b557f9f5-w77cs        0/1     Terminating       0          19s
demo          mongo-sh-mongos-598658d8f9-tmwvb        0/1     PodInitializing   0          7s
demo          mongo-sh-mongos-598658d8f9-tmwvb        0/1     Running           0          8s
demo          mongo-sh-mongos-598658d8f9-tmwvb        1/1     Running           0          10s
demo          mongo-sh-mongos-69b557f9f5-6z2s4        1/1     Terminating       0          6m6s
demo          mongo-sh-mongos-598658d8f9-464xr        0/1     Pending           0          0s
demo          mongo-sh-mongos-598658d8f9-464xr        0/1     Pending           0          0s
demo          mongo-sh-mongos-598658d8f9-464xr        0/1     Init:0/2          0          0s
demo          mongo-sh-mongos-69b557f9f5-6z2s4        0/1     Terminating       0          6m7s
demo          mongo-sh-mongos-598658d8f9-464xr        0/1     Init:1/2          0          2s
demo          mongo-sh-mongos-598658d8f9-464xr        0/1     Init:1/2          0          3s
demo          mongo-sh-mongos-598658d8f9-464xr        0/1     PodInitializing   0          6s
demo          mongo-sh-mongos-69b557f9f5-6z2s4        0/1     Terminating       0          6m13s
demo          mongo-sh-mongos-69b557f9f5-6z2s4        0/1     Terminating       0          6m13s
demo          mongo-sh-mongos-598658d8f9-464xr        0/1     Running           0          7s
demo          mongo-sh-mongos-598658d8f9-464xr        1/1     Running           0          14s
demo          mongo-sh-mongos-69b557f9f5-2qvb7        1/1     Terminating       0          6m21s
demo          mongo-sh-mongos-69b557f9f5-2qvb7        0/1     Terminating       0          6m22s
demo          mongo-sh-mongos-69b557f9f5-2qvb7        0/1     Terminating       0          6m23s
demo          mongo-sh-mongos-69b557f9f5-2qvb7        0/1     Terminating       0          6m23s

You can see that an extra statefulset mongo-sh-shard3 is created as 4th shard and one extra mongos instance also came up.

Notice that, all new mongos instances came up replacing old instances because of some changes in shard config. This update strategy follows spec.shardTopology.mongos.strategy, which is optional. If not provided, kubernetes will use default deploymentStrategy, ie. RollingUpdate. See more about Deployment Strategy.

$ kubectl get deploy -n demo -w
NAME              READY   UP-TO-DATE   AVAILABLE   AGE
mongo-sh-mongos   2/2     2            2           12m
mongo-sh-mongos   2/3     2            2           13m
mongo-sh-mongos   2/3     2            2           13m
mongo-sh-mongos   2/3     2            2           13m
mongo-sh-mongos   2/3     3            2           13m
mongo-sh-mongos   3/3     3            3           13m

Now check sh.status() in mongos,

$ kubectl get po -n demo -l mongodb.kubedb.com/node.mongos=mongo-sh-mongos
NAME                               READY   STATUS    RESTARTS   AGE
mongo-sh-mongos-598658d8f9-6j544   1/1     Running   0          17m
mongo-sh-mongos-598658d8f9-s8gn4   1/1     Running   0          9m54s
mongo-sh-mongos-598658d8f9-tmwvb   1/1     Running   0          16m


$ kubectl exec -it mongo-sh-mongos-598658d8f9-6j544 -n demo bash

mongodb@mongo-sh-mongos-598658d8f9-6j544:/$ mongo admin -u root -p 7QiqLcuSCmZ8PU5a

mongos> sh.status()
--- Sharding Status ---
  sharding version: {
  	"_id" : 1,
  	"minCompatibleVersion" : 5,
  	"currentVersion" : 6,
  	"clusterId" : ObjectId("5cc7ed91d06f28b1b3c64c66")
  }
  shards:
        {  "_id" : "shard0",  "host" : "shard0/mongo-sh-shard0-0.mongo-sh-shard0-gvr.demo.svc.cluster.local:27017,mongo-sh-shard0-1.mongo-sh-shard0-gvr.demo.svc.cluster.local:27017,mongo-sh-shard0-2.mongo-sh-shard0-gvr.demo.svc.cluster.local:27017",  "state" : 1 }
        {  "_id" : "shard1",  "host" : "shard1/mongo-sh-shard1-0.mongo-sh-shard1-gvr.demo.svc.cluster.local:27017,mongo-sh-shard1-1.mongo-sh-shard1-gvr.demo.svc.cluster.local:27017,mongo-sh-shard1-2.mongo-sh-shard1-gvr.demo.svc.cluster.local:27017",  "state" : 1 }
        {  "_id" : "shard2",  "host" : "shard2/mongo-sh-shard2-0.mongo-sh-shard2-gvr.demo.svc.cluster.local:27017,mongo-sh-shard2-1.mongo-sh-shard2-gvr.demo.svc.cluster.local:27017,mongo-sh-shard2-2.mongo-sh-shard2-gvr.demo.svc.cluster.local:27017",  "state" : 1 }
        {  "_id" : "shard3",  "host" : "shard3/mongo-sh-shard3-0.mongo-sh-shard3-gvr.demo.svc.cluster.local:27017,mongo-sh-shard3-1.mongo-sh-shard3-gvr.demo.svc.cluster.local:27017,mongo-sh-shard3-2.mongo-sh-shard3-gvr.demo.svc.cluster.local:27017",  "state" : 1 }
  active mongoses:
        "3.6.12" : 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)
        {  "_id" : "demo",  "primary" : "shard2",  "partitioned" : false }
        {  "_id" : "test",  "primary" : "shard1",  "partitioned" : true }
                test.testcoll
                        shard key: { "myfield" : 1 }
                        unique: false
                        balancing: true
                        chunks:
                                shard1	1
                        { "myfield" : { "$minKey" : 1 } } -->> { "myfield" : { "$maxKey" : 1 } } on : shard1 Timestamp(1, 0)

Pause Database

When, terminationPolicy is DoNotTerminate, KubeDB takes advantage of ValidationWebhook feature in Kubernetes 1.9.0 or later clusters to implement DoNotTerminate feature. If admission webhook is enabled, It prevents users from deleting the database as long as the spec.terminationPolicy is set to DoNotTerminate.

Since the MongoDB object created in this tutorial has spec.terminationPolicy set to Pause (default), if you delete the MongoDB object, KubeDB operator will create a dormant database while deleting the StatefulSet and its pods but leaves the PVCs unchanged.

$ kubedb delete mg mongo-sh -n demo
mongodb.kubedb.com "mongo-sh" deleted

$ kubedb get drmn -n demo mongo-sh
NAME       STATUS    AGE
mongo-sh   Pausing   13s

$ kubedb get drmn -n demo mongo-sh
NAME       STATUS   AGE
mongo-sh   Paused   52s
$ kubedb get drmn -n demo mongo-sh -o yaml
apiVersion: kubedb.com/v1alpha1
kind: DormantDatabase
metadata:
  creationTimestamp: "2019-04-29T11:24:24Z"
  finalizers:
  - kubedb.com
  generation: 1
  labels:
    kubedb.com/kind: MongoDB
  name: mongo-sh
  namespace: demo
  resourceVersion: "35082"
  selfLink: /apis/kubedb.com/v1alpha1/namespaces/demo/dormantdatabases/mongo-sh
  uid: 579c2c2d-6a71-11e9-a871-080027a851ba
spec:
  origin:
    metadata:
      creationTimestamp: "2019-04-29T09:13:56Z"
      name: mongo-sh
      namespace: demo
    spec:
      mongodb:
        certificateSecret:
          secretName: mongo-sh-keyfile
        databaseSecret:
          secretName: mongo-sh-auth
        serviceTemplate:
          metadata: {}
          spec: {}
        shardTopology:
          configServer:
            podTemplate:
              controller: {}
              metadata: {}
              spec:
                livenessProbe:
                  exec:
                    command:
                    - mongo
                    - --eval
                    - db.adminCommand('ping')
                  failureThreshold: 3
                  periodSeconds: 10
                  successThreshold: 1
                  timeoutSeconds: 5
                readinessProbe:
                  exec:
                    command:
                    - mongo
                    - --eval
                    - db.adminCommand('ping')
                  failureThreshold: 3
                  periodSeconds: 10
                  successThreshold: 1
                  timeoutSeconds: 1
                resources: {}
                securityContext:
                  fsGroup: 999
                  runAsNonRoot: true
                  runAsUser: 999
            replicas: 3
            storage:
              dataSource: null
              resources:
                requests:
                  storage: 1Gi
              storageClassName: standard
          mongos:
            podTemplate:
              controller: {}
              metadata: {}
              spec:
                livenessProbe:
                  exec:
                    command:
                    - mongo
                    - --eval
                    - db.adminCommand('ping')
                  failureThreshold: 3
                  periodSeconds: 10
                  successThreshold: 1
                  timeoutSeconds: 5
                readinessProbe:
                  exec:
                    command:
                    - mongo
                    - --eval
                    - db.adminCommand('ping')
                  failureThreshold: 3
                  periodSeconds: 10
                  successThreshold: 1
                  timeoutSeconds: 1
                resources: {}
                securityContext:
                  fsGroup: 999
                  runAsNonRoot: true
                  runAsUser: 999
            replicas: 2
            strategy:
              type: RollingUpdate
          shard:
            podTemplate:
              controller: {}
              metadata: {}
              spec:
                livenessProbe:
                  exec:
                    command:
                    - mongo
                    - --eval
                    - db.adminCommand('ping')
                  failureThreshold: 3
                  periodSeconds: 10
                  successThreshold: 1
                  timeoutSeconds: 5
                readinessProbe:
                  exec:
                    command:
                    - mongo
                    - --eval
                    - db.adminCommand('ping')
                  failureThreshold: 3
                  periodSeconds: 10
                  successThreshold: 1
                  timeoutSeconds: 1
                resources: {}
                securityContext:
                  fsGroup: 999
                  runAsNonRoot: true
                  runAsUser: 999
            replicas: 3
            shards: 3
            storage:
              dataSource: null
              resources:
                requests:
                  storage: 1Gi
              storageClassName: standard
        storageType: Durable
        terminationPolicy: Pause
        updateStrategy:
          type: RollingUpdate
        version: 3.6-v3
status:
  observedGeneration: 1$16440556888999634490
  pausingTime: "2019-04-29T11:24:41Z"
  phase: Paused

Here,

  • spec.origin is the spec of the original spec of the original MongoDB object.
  • status.phase points to the current database state Paused.

Resume Dormant Database

To resume the database from the dormant state, create same MongoDB object with same Spec.

In this tutorial, the dormant database can be resumed by creating original MongoDB object.

The below command will resume the DormantDatabase mongo-sh.

$ kubectl create -f https://raw.githubusercontent.com/kubedb/cli/0.12.0/docs/examples/mongodb/clustering/mongo-sh.yaml
mongodb.kubedb.com/mongo-sh created
$ kubectl get mg -n demo
NAME       VERSION   STATUS    AGE
mongo-sh   3.6-v3    Running   6m27s

Now, If you again exec into pod and look for previous data, you will see that, all the data persists.

$ kubectl get po -n demo -l mongodb.kubedb.com/node.mongos=mongo-sh-mongos
NAME                               READY   STATUS    RESTARTS   AGE
mongo-sh-mongos-69b557f9f5-62j76   1/1     Running   0          3m52s
mongo-sh-mongos-69b557f9f5-tdn69   1/1     Running   0          3m52s


$ kubectl exec -it mongo-sh-mongos-69b557f9f5-62j76 -n demo bash

mongodb@mongo-sh-mongos-69b557f9f5-62j76:/$ mongo admin -u root -p 7QiqLcuSCmZ8PU5a

mongos> use test;
switched to db test

mongos> db.testcoll.find();
{ "_id" : ObjectId("5cc6d6f656a9ddd30be2c12a"), "myfield" : "a", "otherfield" : "b" }
{ "_id" : ObjectId("5cc6d71e56a9ddd30be2c12b"), "myfield" : "c", "otherfield" : "d", "kube" : "db" }

mongos> sh.status()
--- Sharding Status ---
  sharding version: {
  	"_id" : 1,
  	"minCompatibleVersion" : 5,
  	"currentVersion" : 6,
  	"clusterId" : ObjectId("5cc6c061f439d076e04d737b")
  }
  shards:
        {  "_id" : "shard0",  "host" : "shard0/mongo-sh-shard0-0.mongo-sh-shard0-gvr.demo.svc.cluster.local:27017,mongo-sh-shard0-1.mongo-sh-shard0-gvr.demo.svc.cluster.local:27017,mongo-sh-shard0-2.mongo-sh-shard0-gvr.demo.svc.cluster.local:27017",  "state" : 1 }
        {  "_id" : "shard1",  "host" : "shard1/mongo-sh-shard1-0.mongo-sh-shard1-gvr.demo.svc.cluster.local:27017,mongo-sh-shard1-1.mongo-sh-shard1-gvr.demo.svc.cluster.local:27017,mongo-sh-shard1-2.mongo-sh-shard1-gvr.demo.svc.cluster.local:27017",  "state" : 1 }
        {  "_id" : "shard2",  "host" : "shard2/mongo-sh-shard2-0.mongo-sh-shard2-gvr.demo.svc.cluster.local:27017,mongo-sh-shard2-1.mongo-sh-shard2-gvr.demo.svc.cluster.local:27017,mongo-sh-shard2-2.mongo-sh-shard2-gvr.demo.svc.cluster.local:27017",  "state" : 1 }
  active mongoses:
        "3.6.12" : 2
  autosplit:
        Currently enabled: yes
  balancer:
        Currently enabled:  yes
        Currently running:  no
        Failed balancer rounds in last 5 attempts:  5
        Last reported error:  Could not find host matching read preference { mode: "primary" } for set shard2
        Time of Reported error:  Mon Apr 29 2019 11:30:33 GMT+0000 (UTC)
        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)
        {  "_id" : "demo",  "primary" : "shard2",  "partitioned" : false }
        {  "_id" : "test",  "primary" : "shard1",  "partitioned" : true }
                test.testcoll
                        shard key: { "myfield" : 1 }
                        unique: false
                        balancing: true
                        chunks:
                                shard1	1
                        { "myfield" : { "$minKey" : 1 } } -->> { "myfield" : { "$maxKey" : 1 } } on : shard1 Timestamp(1, 0)

WipeOut DormantDatabase

You can wipe out a DormantDatabase while deleting the object by setting spec.wipeOut to true. KubeDB operator will delete any relevant resources of this MongoDB database (i.e, PVCs, Secrets, Snapshots). It will also delete snapshot data stored in the Cloud Storage buckets.

$ kubedb delete mg mongo-sh -n demo
mongodb.kubedb.com "mongo-sh" deleted
$ kubedb edit drmn -n demo mongo-sh
apiVersion: kubedb.com/v1alpha1
kind: DormantDatabase
metadata:
  name: mongo-sh
  namespace: demo
  ...
spec:
  wipeOut: true
  ...
status:
  phase: Paused
  ...

If spec.wipeOut is not set to true while deleting the dormantdatabase object, then only this object will be deleted and kubedb-operator won’t delete related Secrets, PVCs, and Snapshots. So, users still can access the stored data in the cloud storage buckets as well as PVCs.

Delete DormantDatabase

As it is already discussed above, DormantDatabase can be deleted with or without wiping out the resources. To delete the dormantdatabase,

$ kubectl delete drmn mongo-sh -n demo
dormantdatabase.kubedb.com "mongo-sh" deleted

Cleaning up

To cleanup the Kubernetes resources created by this tutorial, run:

kubectl patch -n demo mg/mongo-sh -p '{"spec":{"terminationPolicy":"WipeOut"}}' --type="merge"
kubectl delete -n demo mg/mongo-sh

kubectl patch -n demo drmn/mongo-sh -p '{"spec":{"wipeOut":true}}' --type="merge"
kubectl delete -n demo drmn/mongo-sh

kubectl delete ns demo

Next Steps