New to KubeDB? Please start here.

MongoDB QuickStart

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

  lifecycle

Before You Begin

  • At first, 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 kind.

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

  • StorageClass is required to run KubeDB. Check the available StorageClass in cluster.

    $ kubectl get storageclasses
    NAME                 PROVISIONER             RECLAIMPOLICY   VOLUMEBINDINGMODE      ALLOWVOLUMEEXPANSION   AGE
    standard (default)   rancher.io/local-path   Delete          WaitForFirstConsumer   false                  9h
    
  • 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/docs.

Find Available MongoDBVersion

When you have installed KubeDB, it has created MongoDBVersion crd for all supported MongoDB versions. Check 0

$ kubectl get mongodbversions
NAME             VERSION   DB_IMAGE                                 DEPRECATED   AGE
3.4.17-v1        3.4.17    kubedb/mongo:3.4.17-v1                                8h
3.4.22-v1        3.4.22    kubedb/mongo:3.4.22-v1                                8h
3.6.13-v1        3.6.13    kubedb/mongo:3.6.13-v1                                8h
3.6.18-percona   3.6.18    percona/percona-server-mongodb:3.6.18                 8h
3.6.8-v1         3.6.8     kubedb/mongo:3.6.8-v1                                 8h
4.0.10-percona   4.0.10    percona/percona-server-mongodb:4.0.10                 8h
4.0.11-v1        4.0.11    kubedb/mongo:4.0.11-v1                                8h
4.0.3-v1         4.0.3     kubedb/mongo:4.0.3-v1                                 8h
4.0.5-v3         4.0.5     kubedb/mongo:4.0.5-v3                                 8h
4.1.13-v1        4.1.13    kubedb/mongo:4.1.13-v1                                8h
4.1.4-v1         4.1.4     kubedb/mongo:4.1.4-v1                                 8h
4.1.7-v3         4.1.7     kubedb/mongo:4.1.7-v3                                 8h
4.2.3            4.2.3     kubedb/mongo:4.2.3                                    8h
4.2.7-percona    4.2.7     percona/percona-server-mongodb:4.2.7-7                8h

Create a MongoDB database

KubeDB implements a MongoDB CRD to define the specification of a MongoDB database. Below is the MongoDB object created in this tutorial.

apiVersion: kubedb.com/v1alpha2
kind: MongoDB
metadata:
  name: mgo-quickstart
  namespace: demo
spec:
  version: "4.2.3"
  storageType: Durable
  storage:
    storageClassName: "standard"
    accessModes:
    - ReadWriteOnce
    resources:
      requests:
        storage: 1Gi
  terminationPolicy: DoNotTerminate
$ kubectl create -f https://github.com/kubedb/docs/raw/v2021.04.16/docs/examples/mongodb/quickstart/demo-1.yaml
mongodb.kubedb.com/mgo-quickstart created

Here,

  • spec.version is name of the MongoDBVersion crd where the docker images are specified. In this tutorial, a MongoDB 4.2.3 database is created.
  • spec.storageType specifies the type of storage that will be used for MongoDB database. It can be Durable or Ephemeral. Default value of this field is Durable. If Ephemeral is used then KubeDB will create MongoDB database using EmptyDir volume. In this case, you don’t have to specify spec.storage field. This is useful for testing purposes.
  • spec.storage specifies PVC spec that will be dynamically allocated to store data for this database. This storage spec will be passed to the StatefulSet created by KubeDB operator to run database pods. You can specify any StorageClass available in your cluster with appropriate resource requests.
  • spec.terminationPolicy gives flexibility whether to nullify(reject) the delete operation of MongoDB crd or which resources KubeDB should keep or delete when you delete MongoDB crd. If admission webhook is enabled, It prevents users from deleting the database as long as the spec.terminationPolicy is set to DoNotTerminate. Learn details of all TerminationPolicy here

Note: spec.storage section is used to create PVC for database pod. It will create PVC with storage size specified instorage.resources.requests field. Don’t specify limits here. PVC does not get resized automatically.

KubeDB operator watches for MongoDB objects using Kubernetes api. When a MongoDB object is created, KubeDB operator will create a new StatefulSet and a Service with the matching MongoDB object name. KubeDB operator will also create a governing service for StatefulSets with the name <mongodb-name>-pods.

$ kubectl dba describe mg -n demo mgo-quickstart
Name:               mgo-quickstart
Namespace:          demo
CreationTimestamp:  Thu, 11 Feb 2021 10:54:22 +0600
Labels:             <none>
Annotations:        kubectl.kubernetes.io/last-applied-configuration={"apiVersion":"kubedb.com/v1alpha2","kind":"MongoDB","metadata":{"annotations":{},"name":"mgo-quickstart","namespace":"demo"},"spec":{"storage":{"acces...
Replicas:           1  total
Status:             Ready
StorageType:        Durable
Volume:
  StorageClass:      standard
  Capacity:          1Gi
  Access Modes:      RWO
Paused:              false
Halted:              false
Termination Policy:  DoNotTerminate

StatefulSet:          
  Name:               mgo-quickstart
  CreationTimestamp:  Thu, 11 Feb 2021 10:54:22 +0600
  Labels:               app.kubernetes.io/component=database
                        app.kubernetes.io/instance=mgo-quickstart
                        app.kubernetes.io/managed-by=kubedb.com
                        app.kubernetes.io/name=mongodbs.kubedb.com
  Annotations:        <none>
  Replicas:           824639033752 desired | 1 total
  Pods Status:        1 Running / 0 Waiting / 0 Succeeded / 0 Failed

Service:        
  Name:         mgo-quickstart
  Labels:         app.kubernetes.io/component=database
                  app.kubernetes.io/instance=mgo-quickstart
                  app.kubernetes.io/managed-by=kubedb.com
                  app.kubernetes.io/name=mongodbs.kubedb.com
  Annotations:  <none>
  Type:         ClusterIP
  IP:           fd00:10:96::cc87
  Port:         primary  27017/TCP
  TargetPort:   db/TCP
  Endpoints:    [fd00:10:244::27]:27017

Service:        
  Name:         mgo-quickstart-pods
  Labels:         app.kubernetes.io/component=database
                  app.kubernetes.io/instance=mgo-quickstart
                  app.kubernetes.io/managed-by=kubedb.com
                  app.kubernetes.io/name=mongodbs.kubedb.com
  Annotations:  <none>
  Type:         ClusterIP
  IP:           None
  Port:         db  27017/TCP
  TargetPort:   db/TCP
  Endpoints:    [fd00:10:244::27]:27017

Auth Secret:
  Name:         mgo-quickstart-auth
  Labels:         app.kubernetes.io/component=database
                  app.kubernetes.io/instance=mgo-quickstart
                  app.kubernetes.io/managed-by=kubedb.com
                  app.kubernetes.io/name=mongodbs.kubedb.com
  Annotations:  <none>
  Type:         Opaque
  Data:
    username:  4 bytes
    password:  16 bytes

AppBinding:
  Metadata:
    Annotations:
      kubectl.kubernetes.io/last-applied-configuration:  {"apiVersion":"kubedb.com/v1alpha2","kind":"MongoDB","metadata":{"annotations":{},"name":"mgo-quickstart","namespace":"demo"},"spec":{"storage":{"accessModes":["ReadWriteOnce"],"resources":{"requests":{"storage":"1Gi"}},"storageClassName":"standard"},"storageType":"Durable","terminationPolicy":"DoNotTerminate","version":"4.2.3"}}

    Creation Timestamp:  2021-02-11T04:54:40Z
    Labels:
      app.kubernetes.io/component:   database
      app.kubernetes.io/instance:    mgo-quickstart
      app.kubernetes.io/managed-by:  kubedb.com
      app.kubernetes.io/name:        mongodbs.kubedb.com
    Name:                            mgo-quickstart
    Namespace:                       demo
  Spec:
    Client Config:
      Service:
        Name:    mgo-quickstart
        Port:    27017
        Scheme:  mongodb
    Secret:
      Name:   mgo-quickstart-auth
    Type:     kubedb.com/mongodb
    Version:  4.2.3

Events:
  Type    Reason      Age   From              Message
  ----    ------      ----  ----              -------
  Normal  Successful  46s   MongoDB operator  Successfully created Service
  Normal  Successful  46s   MongoDB operator  Successfully  stats service
  Normal  Successful  46s   MongoDB operator  Successfully  stats service
  Normal  Successful  46s   MongoDB operator  Successfully created stats service
  Normal  Successful  28s   MongoDB operator  Successfully patched MongoDB
  Normal  Successful  28s   MongoDB operator  Successfully  stats service
  Normal  Successful  28s   MongoDB operator  Successfully patched StatefulSet demo/mgo-quickstart
  Normal  Successful  28s   MongoDB operator  Successfully patched MongoDB
  Normal  Successful  28s   MongoDB operator  Successfully created appbinding
  Normal  Successful  28s   MongoDB operator  Successfully  stats service
  Normal  Successful  28s   MongoDB operator  Successfully  stats service
  Normal  Successful  28s   MongoDB operator  Successfully patched StatefulSet demo/mgo-quickstart
  Normal  Successful  4s    MongoDB operator  Successfully  stats service
  Normal  Successful  4s    MongoDB operator  Successfully patched StatefulSet demo/mgo-quickstart
  Normal  Successful  4s    MongoDB operator  Successfully patched MongoDB
  Normal  Successful  4s    MongoDB operator  Successfully  stats service
  Normal  Successful  4s    MongoDB operator  Successfully patched StatefulSet demo/mgo-quickstart
  Normal  Successful  4s    MongoDB operator  Successfully patched MongoDB
  Normal  Successful  4s    MongoDB operator  Successfully  stats service
  Normal  Successful  4s    MongoDB operator  Successfully patched StatefulSet demo/mgo-quickstart
  Normal  Successful  4s    MongoDB operator  Successfully patched MongoDB

$ kubectl get statefulset -n demo
NAME             READY   AGE
mgo-quickstart   1/1     105s

$ kubectl get pvc -n demo
NAME                       STATUS   VOLUME                                     CAPACITY   ACCESS MODES   STORAGECLASS   AGE
datadir-mgo-quickstart-0   Bound    pvc-9c738632-29cf-11e9-aebf-080027875192   1Gi        RWO            standard       16m

$ kubectl get pv -n demo
NAME                                       CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS   CLAIM                           STORAGECLASS   REASON   AGE
pvc-9c738632-29cf-11e9-aebf-080027875192   1Gi        RWO            Delete           Bound    demo/datadir-mgo-quickstart-0   standard                17m

$ kubectl get service -n demo
NAME                 TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)     AGE
mgo-quickstart       ClusterIP   10.111.237.184   <none>        27017/TCP   18m
mgo-quickstart-pods  ClusterIP   None             <none>        27017/TCP   18m

KubeDB operator sets the status.phase to Ready once the database is successfully created. Run the following command to see the modified MongoDB object:

$ kubectl get mg -n demo mgo-quickstart -o yaml
apiVersion: kubedb.com/v1alpha2
kind: MongoDB
metadata:
  annotations:
    kubectl.kubernetes.io/last-applied-configuration: |
            {"apiVersion":"kubedb.com/v1alpha2","kind":"MongoDB","metadata":{"annotations":{},"name":"mgo-quickstart","namespace":"demo"},"spec":{"storage":{"accessModes":["ReadWriteOnce"],"resources":{"requests":{"storage":"1Gi"}},"storageClassName":"standard"},"storageType":"Durable","terminationPolicy":"DoNotTerminate","version":"4.2.3"}}
  creationTimestamp: "2021-02-09T14:06:57Z"
  finalizers:
    - kubedb.com
  generation: 2
  managedFields:
    - apiVersion: kubedb.com/v1alpha2
      fieldsType: FieldsV1
      fieldsV1:
        f:metadata:
          f:annotations:
            .: {}
            f:kubectl.kubernetes.io/last-applied-configuration: {}
        f:spec:
          .: {}
          f:storage:
            .: {}
            f:accessModes: {}
            f:resources:
              .: {}
              f:requests:
                .: {}
                f:storage: {}
            f:storageClassName: {}
          f:storageType: {}
          f:terminationPolicy: {}
          f:version: {}
      manager: kubectl-client-side-apply
      operation: Update
      time: "2021-02-09T14:06:57Z"
    - apiVersion: kubedb.com/v1alpha2
      fieldsType: FieldsV1
      fieldsV1:
        f:metadata:
          f:finalizers: {}
        f:spec:
          f:authSecret:
            .: {}
            f:name: {}
        f:status:
          .: {}
          f:conditions: {}
          f:observedGeneration: {}
          f:phase: {}
      manager: mg-operator
      operation: Update
      time: "2021-02-09T14:06:57Z"
  name: mgo-quickstart
  namespace: demo
  resourceVersion: "59940"
  uid: b0bcf12e-7a3a-4f15-9493-461e6087964b
spec:
  authSecret:
    name: mgo-quickstart-auth
  podTemplate:
    controller: {}
    metadata: {}
    spec:
      affinity:
        podAntiAffinity:
          preferredDuringSchedulingIgnoredDuringExecution:
            - podAffinityTerm:
                labelSelector:
                  matchLabels:
                    app.kubernetes.io/instance: mgo-quickstart
                    app.kubernetes.io/managed-by: kubedb.com
                    app.kubernetes.io/name: mongodbs.kubedb.com
                namespaces:
                  - demo
                topologyKey: kubernetes.io/hostname
              weight: 100
            - podAffinityTerm:
                labelSelector:
                  matchLabels:
                    app.kubernetes.io/instance: mgo-quickstart
                    app.kubernetes.io/managed-by: kubedb.com
                    app.kubernetes.io/name: mongodbs.kubedb.com
                namespaces:
                  - demo
                topologyKey: failure-domain.beta.kubernetes.io/zone
              weight: 50
      livenessProbe:
        exec:
          command:
            - bash
            - -c
            - "set -x; if [[ $(mongo admin --host=localhost  --username=$MONGO_INITDB_ROOT_USERNAME
            --password=$MONGO_INITDB_ROOT_PASSWORD --authenticationDatabase=admin
            --quiet --eval \"db.adminCommand('ping').ok\" ) -eq \"1\" ]]; then \n
            \         exit 0\n        fi\n        exit 1"
        failureThreshold: 3
        periodSeconds: 10
        successThreshold: 1
        timeoutSeconds: 5
      readinessProbe:
        exec:
          command:
            - bash
            - -c
            - "set -x; if [[ $(mongo admin --host=localhost  --username=$MONGO_INITDB_ROOT_USERNAME
            --password=$MONGO_INITDB_ROOT_PASSWORD --authenticationDatabase=admin
            --quiet --eval \"db.adminCommand('ping').ok\" ) -eq \"1\" ]]; then \n
            \         exit 0\n        fi\n        exit 1"
        failureThreshold: 3
        periodSeconds: 10
        successThreshold: 1
        timeoutSeconds: 1
      resources:
        limits:
          cpu: 500m
          memory: 1Gi
        requests:
          cpu: 500m
          memory: 1Gi
      serviceAccountName: mgo-quickstart
  replicas: 1
  sslMode: disabled
  storage:
    accessModes:
      - ReadWriteOnce
    resources:
      requests:
        storage: 1Gi
    storageClassName: standard
  storageEngine: wiredTiger
  storageType: Durable
  terminationPolicy: DoNotTerminate
  version: 4.2.3
status:
  conditions:
    - lastTransitionTime: "2021-02-09T14:06:57Z"
      message: 'The KubeDB operator has started the provisioning of MongoDB: demo/mgo-quickstart'
      reason: DatabaseProvisioningStartedSuccessfully
      status: "True"
      type: ProvisioningStarted
    - lastTransitionTime: "2021-02-09T14:07:16Z"
      message: All desired replicas are ready.
      reason: AllReplicasReady
      status: "True"
      type: ReplicaReady
    - lastTransitionTime: "2021-02-09T14:07:42Z"
      message: 'The MongoDB: demo/mgo-quickstart is accepting client requests.'
      observedGeneration: 2
      reason: DatabaseAcceptingConnectionRequest
      status: "True"
      type: AcceptingConnection
    - lastTransitionTime: "2021-02-09T14:07:42Z"
      message: 'The MongoDB: demo/mgo-quickstart is ready.'
      observedGeneration: 2
      reason: ReadinessCheckSucceeded
      status: "True"
      type: Ready
    - lastTransitionTime: "2021-02-09T14:07:42Z"
      message: 'The MongoDB: demo/mgo-quickstart is successfully provisioned.'
      observedGeneration: 2
      reason: DatabaseSuccessfullyProvisioned
      status: "True"
      type: Provisioned
  observedGeneration: 2
  phase: Ready

Please note that KubeDB operator has created a new Secret called mgo-quickstart-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.authSecret.name. While creating this secret manually, make sure the secret contains these two keys containing data username and password. For more details, please see here.

Now, you can connect to this database through mongo-shell. In this tutorial, we are connecting to the MongoDB server from inside the pod.

$ kubectl get secrets -n demo mgo-quickstart-auth -o jsonpath='{.data.\username}' | base64 -d
root

$ kubectl get secrets -n demo mgo-quickstart-auth -o jsonpath='{.data.\password}' | base64 -d
t1QJppJw_B13UIES

$ kubectl exec -it mgo-quickstart-0 -n demo sh

> mongo admin

> db.auth("root","t1QJppJw_B13UIES")
1

> show dbs
admin  0.000GB
local  0.000GB
mydb   0.000GB

> show users
{
	"_id" : "admin.root",
	"userId" : UUID("7e7f3e5d-4ebd-438a-9c40-91ed59bf242f"),
	"user" : "root",
	"db" : "admin",
	"roles" : [
		{
			"role" : "root",
			"db" : "admin"
		}
	],
	"mechanisms" : [
		"SCRAM-SHA-1",
		"SCRAM-SHA-256"
	]
}

> use newdb
switched to db newdb

> db.movie.insert({"name":"batman"});
WriteResult({ "nInserted" : 1 })

> db.movie.find().pretty()
{ "_id" : ObjectId("5a2e435d7ec14e7bda785f16"), "name" : "batman" }

> exit
bye

DoNotTerminate Property

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. You can see this below:

$ kubectl delete mg mgo-quickstart -n demo
Error from server (BadRequest): admission webhook "mongodb.validators.kubedb.com" denied the request: mongodb "mgo-quickstart" can't be halted. To delete, change spec.terminationPolicy

Halt Database

When TerminationPolicy is set to halt, and you delete the mongodb object, the KubeDB operator will delete the StatefulSet and its pods but leaves the PVCs, secrets and database backup (snapshots) intact. Learn details of all TerminationPolicy here.

You can also keep the mongodb object and halt the database to resume it again later. If you halt the database, the kubedb operator will delete the statefulsets and services but will keep the mongodb object, pvcs, secrets and backup (snapshots).

To halt the database, first you have to set the terminationPolicy to Halt in existing database. You can use the below command to set the terminationPolicy to Halt, if it is not already set.

$ kubectl patch -n demo mg/mgo-quickstart -p '{"spec":{"terminationPolicy":"Halt"}}' --type="merge"
mongodb.kubedb.com/mgo-quickstart patched

Then, you have to set the spec.halted as true to set the database in a Halted state. You can use the below command.

$ kubectl patch -n demo mg/mgo-quickstart -p '{"spec":{"halted":true}}' --type="merge"
mongodb.kubedb.com/mgo-quickstart patched

After that, kubedb will delete the statefulsets and services and you can see the database Phase as Halted.

Now, you can run the following command to get all mongodb resources in demo namespaces,

$ kubectl get mg,sts,svc,secret,pvc -n demo
NAME                                VERSION   STATUS   AGE
mongodb.kubedb.com/mgo-quickstart   4.2.3     Halted   9m43s

NAME                            TYPE                                  DATA   AGE
secret/default-token-x2zcl      kubernetes.io/service-account-token   3      47h
secret/mgo-quickstart-auth      Opaque                                2      23h

NAME                                             STATUS   VOLUME                                     CAPACITY   ACCESS MODES   STORAGECLASS   AGE
persistentvolumeclaim/datadir-mgo-quickstart-0   Bound    pvc-816daa52-ee40-496f-a148-c75344a1b433   1Gi        RWO            standard       9m43s

Resume Halted Database

Now, to resume the database, i.e. to get the same database setup back again, you have to set the the spec.halted as false. You can use the below command.

$ kubectl patch -n demo mg/mgo-quickstart -p '{"spec":{"halted":false}}' --type="merge"
mongodb.kubedb.com/mgo-quickstart patched

When the database is resumed successfully, you can see the database Status is set to Ready.

$ kubectl get mg -n demo
NAME             VERSION   STATUS    AGE
mgo-quickstart   4.2.3     Ready     6m27s

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

$ kubectl exec -it mgo-quickstart-0 -n demo bash

[email protected]:/$ mongo admin -u root -p 7QiqLcuSCmZ8PU5a

rs0:PRIMARY> use newdb
switched to db newdb

rs0:PRIMARY> db.movie.find()
{ "_id" : ObjectId("6024b3e47c614cd582c9bb44"), "name" : "batman" }

Cleaning up

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

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

kubectl delete ns demo

Tips for Testing

If you are just testing some basic functionalities, you might want to avoid additional hassles due to some safety features that are great for production environment. You can follow these tips to avoid them.

  1. Use storageType: Ephemeral. Databases are precious. You might not want to lose your data in your production environment if database pod fail. So, we recommend using spec.storageType: Durable and provide storage spec in spec.storage section. For testing purpose, you can just use spec.storageType: Ephemeral. KubeDB will use emptyDir for storage. You will not require to provide spec.storage section.
  2. Use terminationPolicy: WipeOut. It is nice to be able to resume database. So, we have Halt option which preserves all your PVCs, Secrets, Snapshots etc. If you don’t want to resume database, you can just use spec.terminationPolicy: WipeOut. It will delete everything created by KubeDB for a particular MongoDB crd when you delete the mongodb object. For more details about termination policy, please visit here.

Next Steps