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KubeDB - MongoDB Standalone
This tutorial will show you how to use KubeDB to run a MongoDB Standalone.
Before You Begin
Before proceeding:
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.
To keep things isolated, this tutorial uses a separate namespace called
demothroughout 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.
Deploy MongoDB Standalone
To deploy a MongoDB Standalone, user must have spec.replicaSet & spec.shardTopology options in Mongodb CRD to be set to nil. Arbiter & Hidden-node are also not supported for standalone mongoDB.
The following is an example of a Mongodb object which creates MongoDB Standalone database.
apiVersion: kubedb.com/v1alpha2
kind: MongoDB
metadata:
name: mg-alone
namespace: demo
spec:
version: "4.2.3"
podTemplate:
spec:
resources:
requests:
cpu: "300m"
memory: "400Mi"
storage:
resources:
requests:
storage: 500Mi
storageClassName: standard
terminationPolicy: WipeOut
$ kubectl create -f https://github.com/kubedb/docs/raw/v2023.06.19/docs/examples/mongodb/clustering/standalone.yaml
mongodb.kubedb.com/mg-alone created
Here,
spec.versionis the version to be used for MongoDB.spec.podTemplatespecifies the resources and other specifications of the pod. Have a look here to know the other subfields of the podTemplate.spec.storagespecifies the StorageClass of PVC 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. So, each members will have a pod of this storage configuration. You can specify any StorageClass available in your cluster with appropriate resource requests.
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 mg-alone
Name: mg-alone
Namespace: demo
CreationTimestamp: Fri, 04 Nov 2022 10:30:07 +0600
Labels: <none>
Annotations: kubectl.kubernetes.io/last-applied-configuration={"apiVersion":"kubedb.com/v1alpha2","kind":"MongoDB","metadata":{"annotations":{},"name":"mg-alone","namespace":"demo"},"spec":{"podTemplate":{"spec":{...
Replicas: 1 total
Status: Ready
StorageType: Durable
Volume:
StorageClass: standard
Capacity: 500Mi
Paused: false
Halted: false
Termination Policy: WipeOut
StatefulSet:
Name: mg-alone
CreationTimestamp: Fri, 04 Nov 2022 10:30:07 +0600
Labels: app.kubernetes.io/component=database
app.kubernetes.io/instance=mg-alone
app.kubernetes.io/managed-by=kubedb.com
app.kubernetes.io/name=mongodbs.kubedb.com
Annotations: <none>
Replicas: 824638445048 desired | 1 total
Pods Status: 1 Running / 0 Waiting / 0 Succeeded / 0 Failed
Service:
Name: mg-alone
Labels: app.kubernetes.io/component=database
app.kubernetes.io/instance=mg-alone
app.kubernetes.io/managed-by=kubedb.com
app.kubernetes.io/name=mongodbs.kubedb.com
Annotations: <none>
Type: ClusterIP
IP: 10.96.47.157
Port: primary 27017/TCP
TargetPort: db/TCP
Endpoints: 10.244.0.25:27017
Service:
Name: mg-alone-pods
Labels: app.kubernetes.io/component=database
app.kubernetes.io/instance=mg-alone
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: 10.244.0.25:27017
Auth Secret:
Name: mg-alone-auth
Labels: app.kubernetes.io/component=database
app.kubernetes.io/instance=mg-alone
app.kubernetes.io/managed-by=kubedb.com
app.kubernetes.io/name=mongodbs.kubedb.com
Annotations: <none>
Type: kubernetes.io/basic-auth
Data:
password: 16 bytes
username: 4 bytes
AppBinding:
Metadata:
Annotations:
kubectl.kubernetes.io/last-applied-configuration: {"apiVersion":"kubedb.com/v1alpha2","kind":"MongoDB","metadata":{"annotations":{},"name":"mg-alone","namespace":"demo"},"spec":{"podTemplate":{"spec":{"resources":{"requests":{"cpu":"300m","memory":"400Mi"}}}},"storage":{"resources":{"requests":{"storage":"500Mi"}},"storageClassName":"standard"},"terminationPolicy":"WipeOut","version":"4.2.3"}}
Creation Timestamp: 2022-11-04T04:30:14Z
Labels:
app.kubernetes.io/component: database
app.kubernetes.io/instance: mg-alone
app.kubernetes.io/managed-by: kubedb.com
app.kubernetes.io/name: mongodbs.kubedb.com
Name: mg-alone
Namespace: demo
Spec:
Client Config:
Service:
Name: mg-alone
Port: 27017
Scheme: mongodb
Parameters:
API Version: config.kubedb.com/v1alpha1
Kind: MongoConfiguration
Stash:
Addon:
Backup Task:
Name: mongodb-backup-4.2.3
Restore Task:
Name: mongodb-restore-4.2.3
Secret:
Name: mg-alone-auth
Type: kubedb.com/mongodb
Version: 4.2.3
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal PhaseChanged 21s MongoDB operator Phase changed from to Provisioning.
Normal Successful 21s MongoDB operator Successfully created governing service
Normal Successful 21s MongoDB operator Successfully created Primary Service
Normal Successful 14s MongoDB operator Successfully patched StatefulSet demo/mg-alone
Normal Successful 14s MongoDB operator Successfully patched MongoDB
Normal Successful 14s MongoDB operator Successfully created appbinding
Normal Successful 14s MongoDB operator Successfully patched MongoDB
Normal Successful 14s MongoDB operator Successfully patched StatefulSet demo/mg-alone
Normal Successful 4s MongoDB operator Successfully patched StatefulSet demo/mg-alone
Normal Successful 4s MongoDB operator Successfully patched MongoDB
Normal PhaseChanged 4s MongoDB operator Phase changed from Provisioning to Ready.
Normal Successful 4s MongoDB operator Successfully patched StatefulSet demo/mg-alone
Normal Successful 4s MongoDB operator Successfully patched MongoDB
$ kubectl get sts,svc,pvc,pv -n demo
NAME READY AGE
statefulset.apps/mg-alone 1/1 65s
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
service/mg-alone ClusterIP 10.96.47.157 <none> 27017/TCP 65s
service/mg-alone-pods ClusterIP None <none> 27017/TCP 65s
NAME STATUS VOLUME CAPACITY ACCESS MODES STORAGECLASS AGE
persistentvolumeclaim/datadir-mg-alone-0 Bound pvc-78328965-1210-4f7a-a508-2749b328a5ac 500Mi RWO standard 65s
NAME CAPACITY ACCESS MODES RECLAIM POLICY STATUS CLAIM STORAGECLASS REASON AGE
persistentvolume/pvc-78328965-1210-4f7a-a508-2749b328a5ac 500Mi RWO Delete Bound demo/datadir-mg-alone-0 standard 62s
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 mg-alone -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":"mg-alone","namespace":"demo"},"spec":{"podTemplate":{"spec":{"resources":{"requests":{"cpu":"300m","memory":"400Mi"}}}},"storage":{"resources":{"requests":{"storage":"500Mi"}},"storageClassName":"standard"},"terminationPolicy":"WipeOut","version":"4.2.3"}}
creationTimestamp: "2022-11-04T04:30:07Z"
finalizers:
- kubedb.com
generation: 2
name: mg-alone
namespace: demo
resourceVersion: "914996"
uid: 55ece68c-8df6-4055-b463-1fcb119f0fb1
spec:
allowedSchemas:
namespaces:
from: Same
authSecret:
name: mg-alone-auth
autoOps: {}
coordinator:
resources: {}
healthChecker:
failureThreshold: 1
periodSeconds: 10
timeoutSeconds: 10
podTemplate:
controller: {}
metadata: {}
spec:
affinity:
podAntiAffinity:
preferredDuringSchedulingIgnoredDuringExecution:
- podAffinityTerm:
labelSelector:
matchLabels:
app.kubernetes.io/instance: mg-alone
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: mg-alone
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: 5
resources:
limits:
memory: 400Mi
requests:
cpu: 300m
memory: 400Mi
serviceAccountName: mg-alone
replicas: 1
sslMode: disabled
storage:
resources:
requests:
storage: 500Mi
storageClassName: standard
storageEngine: wiredTiger
storageType: Durable
terminationPolicy: WipeOut
version: 4.2.3
status:
conditions:
- lastTransitionTime: "2022-11-04T04:30:07Z"
message: 'The KubeDB operator has started the provisioning of MongoDB: demo/mg-alone'
reason: DatabaseProvisioningStartedSuccessfully
status: "True"
type: ProvisioningStarted
- lastTransitionTime: "2022-11-04T04:30:14Z"
message: All desired replicas are ready.
reason: AllReplicasReady
status: "True"
type: ReplicaReady
- lastTransitionTime: "2022-11-04T04:30:24Z"
message: 'The MongoDB: demo/mg-alone is accepting client requests.'
observedGeneration: 2
reason: DatabaseAcceptingConnectionRequest
status: "True"
type: AcceptingConnection
- lastTransitionTime: "2022-11-04T04:30:24Z"
message: 'The MongoDB: demo/mg-alone is ready.'
observedGeneration: 2
reason: ReadinessCheckSucceeded
status: "True"
type: Ready
- lastTransitionTime: "2022-11-04T04:30:24Z"
message: 'The MongoDB: demo/mg-alone 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 mg-alone-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.
Data Insertion
Now, you can connect to this database through mg-alone. In this tutorial, we will insert document on the primary member, and we will see if the data becomes available on secondary members.
At first, insert data inside primary member rs0:PRIMARY.
$ kubectl get secrets -n demo mg-alone-auth -o jsonpath='{.data.\username}' | base64 -d
root
$ kubectl get secrets -n demo mg-alone-auth -o jsonpath='{.data.\password}' | base64 -d
5O4R2ze2bWXcWsdP
$ kubectl exec -it mg-alone-0 -n demo bash
mongodb@mg-alone-0:/$ mongo admin -u root -p 5O4R2ze2bWXcWsdP
MongoDB shell version v4.2.3
connecting to: mongodb://127.0.0.1:27017/admin
MongoDB server version: 4.2.3
Welcome to the MongoDB shell.
> rs.isMaster()
{
"ismaster" : true,
"maxBsonObjectSize" : 16777216,
"maxMessageSizeBytes" : 48000000,
"maxWriteBatchSize" : 100000,
"localTime" : ISODate("2022-11-04T04:45:33.151Z"),
"logicalSessionTimeoutMinutes" : 30,
"connectionId" : 447,
"minWireVersion" : 0,
"maxWireVersion" : 8,
"readOnly" : false,
"ok" : 1
}
> show dbs
admin 0.000GB
config 0.000GB
kubedb-system 0.000GB
local 0.000GB
> use admin
switched to db admin
> show users
{
"_id" : "admin.root",
"userId" : UUID("bd711827-8d7e-4c7c-b9d7-ddb27869b9fb"),
"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("6364996b3bdf351ff67cc7a8"), "name" : "batman" }
> exit
bye
Data availability
As this is a standalone database which doesn’t have multiple replicas, It offers no redundancy & high availability of data. All the data are stored in one place, & deleting that will occur in data lost.
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 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/mg-alone -p '{"spec":{"terminationPolicy":"Halt"}}' --type="merge"
mongodb.kubedb.com/mg-alone 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/mg-alone -p '{"spec":{"halted":true}}' --type="merge"
mongodb.kubedb.com/mg-alone 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/mg-alone 4.2.3 Halted 2m4s
NAME TYPE DATA AGE
secret/mg-alone-auth kubernetes.io/basic-auth 2 2m4s
secret/mongo-ca kubernetes.io/tls 2 15d
NAME STATUS VOLUME CAPACITY ACCESS MODES STORAGECLASS AGE
persistentvolumeclaim/datadir-mg-alone-0 Bound pvc-a1a873a6-4f6d-42eb-a38f-83d36fc44e1a 500Mi RWO standard 2m4s
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/mg-alone -p '{"spec":{"halted":false}}' --type="merge"
mongodb.kubedb.com/mg-alone 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
mg-alone 4.2.3 Ready 6m27s
Now, If you again exec into the primary pod and look for previous data, you will see that, all the data persists.
$ kubectl exec -it mg-alone-1 -n demo bash
mongodb@mg-alone-1:/$ mongo admin -u root -p 7QiqLcuSCmZ8PU5a
> use newdb
switched to db newdb
> show collections
movie
> db.movie.find()
{ "_id" : ObjectId("6364af93b1ae8e7a8467058a"), "name" : "batman" }
Cleaning up
To cleanup the Kubernetes resources created by this tutorial, run:
kubectl patch -n demo mg/mg-alone -p '{"spec":{"terminationPolicy":"WipeOut"}}' --type="merge"
kubectl delete -n demo mg/mg-alone
kubectl delete ns demo
Next Steps
- Deploy MongoDB ReplicaSet
- Backup and Restore process of MongoDB databases using Stash.
- Initialize MongoDB with Script.
- Monitor your MongoDB database with KubeDB using out-of-the-box Prometheus operator.
- Monitor your MongoDB database with KubeDB using out-of-the-box builtin-Prometheus.
- Use private Docker registry to deploy MongoDB with KubeDB.
- Detail concepts of MongoDB object.
- Detail concepts of MongoDBVersion object.
- Want to hack on KubeDB? Check our contribution guidelines.