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MongoDB Sharding with Hidden-node
This tutorial will show you how to use KubeDB to run a sharded MongoDB cluster with hidden node.
Before You Begin
Before proceeding:
Read mongodb hidden-node concept to get the concept about MongoDB Replica Set Hidden-node.
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 Sharded MongoDB Cluster
To deploy a MongoDB Sharding, user have to specify spec.shardTopology option in Mongodb CRD.
The following is an example of a Mongodb object which creates MongoDB Sharding of three type of members.
apiVersion: kubedb.com/v1alpha2
kind: MongoDB
metadata:
name: mongo-sh-hid
namespace: demo
spec:
version: "percona-4.4.10"
shardTopology:
configServer:
replicas: 3
ephemeralStorage: {}
mongos:
replicas: 2
shard:
replicas: 3
shards: 2
ephemeralStorage: {}
storageEngine: inMemory
storageType: Ephemeral
hidden:
podTemplate:
spec:
resources:
requests:
cpu: "400m"
memory: "400Mi"
replicas: 2
storage:
storageClassName: "standard"
accessModes:
- ReadWriteOnce
resources:
requests:
storage: 2Gi
terminationPolicy: WipeOut
$ kubectl create -f https://github.com/kubedb/docs/raw/v2024.2.14/docs/examples/mongodb/hidden-node/sharding.yaml
mongodb.kubedb.com/mongo-sh-hid created
Here,
spec.shardTopologyrepresents the topology configuration for sharding.shardrepresents configuration for Shard component of mongodb.shardsrepresents number of shards for a mongodb deployment. Each shard is deployed as a replicaset.replicasrepresents number of replicas of each shard replicaset.prefixrepresents the prefix of each shard node.configSecretis 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.podTemplateis an optional configuration for pods.storageto specify pvc spec for each node of sharding. You can specify any StorageClass available in your cluster with appropriate resource requests.
configServerrepresents configuration for ConfigServer component of mongodb.replicasrepresents number of replicas for configServer replicaset. Here, configServer is deployed as a replicaset of mongodb.prefixrepresents the prefix of configServer nodes.configSecretis 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.podTemplateis an optional configuration for pods.storageto specify pvc spec for each node of configServer. You can specify any StorageClass available in your cluster with appropriate resource requests.
mongosrepresents configuration for Mongos component of mongodb.Mongosinstances run as stateless components (deployment).replicasrepresents number of replicas ofMongosinstance. Here, Mongos is not deployed as replicaset.prefixrepresents the prefix of mongos nodes.configSecretis 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.podTemplateis an optional configuration for pods.
spec.keyFileSecret(optional) is a secret name that contains keyfile (a random string)againstkey.txtkey. Each mongod instances in the replica set andshardTopologyuses 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 thekeyFileSecretby creating a secret with keykey.txt. See here to create the string forkeyFileSecret. IfkeyFileSecretis not given, KubeDB operator will generate akeyFileSecretitself.spec.storageEngineis set to inMemory, &spec.storageTypeto ephemeral.spec.shardTopology.(configSerer/shard).ephemeralStorageholds the emptyDir volume specifications. 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 ephemeral storage configuration.spec.hiddendenotes hidden-node spec of the deployed MongoDB CRD. There are four fields under it :spec.hidden.podTemplateholds the hidden-node podSpec.nullvalue of it, instructs kubedb operator to use the default hidden-node podTemplate.spec.hidden.configSecretis an optional field to provide custom configuration file for database (i.e mongod.cnf). If specified, this file will be used as configuration file otherwise default configuration file will be used.spec.hidden.replicasholds the number of hidden-node in the replica set.spec.hidden.storagespecifies the StorageClass of PVC dynamically allocated to store data for these hidden-nodes. 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 some new StatefulSets : 1 for mongos, 1 for configServer, and 1 for each of the shard & hidden node. It creates a primary Service with the matching MongoDB object name. KubeDB operator will also create governing services for StatefulSets with the name <mongodb-name>-<node-type>-pods.
MongoDB mongo-sh-hid state,
All the types of nodes Shard, ConfigServer & Mongos are deployed as statefulset.
$ kubectl get mg,sts,svc,pvc,pv -n demo
NAME VERSION STATUS AGE
mongodb.kubedb.com/mongo-sh-hid percona-4.4.10 Ready 4m46s
NAME READY AGE
statefulset.apps/mongo-sh-hid-configsvr 3/3 4m46s
statefulset.apps/mongo-sh-hid-mongos 2/2 2m52s
statefulset.apps/mongo-sh-hid-shard0 3/3 4m46s
statefulset.apps/mongo-sh-hid-shard0-hidden 2/2 3m45s
statefulset.apps/mongo-sh-hid-shard1 3/3 4m46s
statefulset.apps/mongo-sh-hid-shard1-hidden 2/2 3m36s
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
service/mongo-sh-hid ClusterIP 10.96.57.155 <none> 27017/TCP 4m46s
service/mongo-sh-hid-configsvr-pods ClusterIP None <none> 27017/TCP 4m46s
service/mongo-sh-hid-mongos-pods ClusterIP None <none> 27017/TCP 4m46s
service/mongo-sh-hid-shard0-pods ClusterIP None <none> 27017/TCP 4m46s
service/mongo-sh-hid-shard1-pods ClusterIP None <none> 27017/TCP 4m46s
NAME STATUS VOLUME CAPACITY ACCESS MODES STORAGECLASS AGE
persistentvolumeclaim/datadir-mongo-sh-hid-shard0-hidden-0 Bound pvc-9a4fd907-8225-4ed2-90e3-8ca43c0521d2 2Gi RWO standard 3m45s
persistentvolumeclaim/datadir-mongo-sh-hid-shard0-hidden-1 Bound pvc-b77cd5d1-d5c1-433b-90dd-3784c5207cd6 2Gi RWO standard 3m23s
persistentvolumeclaim/datadir-mongo-sh-hid-shard1-hidden-0 Bound pvc-61712454-2038-4692-a6ea-88685d7f34e1 2Gi RWO standard 3m36s
persistentvolumeclaim/datadir-mongo-sh-hid-shard1-hidden-1 Bound pvc-489fb5c9-edee-4cf9-985f-48e04f14f695 2Gi RWO standard 3m14s
NAME CAPACITY ACCESS MODES RECLAIM POLICY STATUS CLAIM STORAGECLASS REASON AGE
persistentvolume/pvc-489fb5c9-edee-4cf9-985f-48e04f14f695 2Gi RWO Delete Bound demo/datadir-mongo-sh-hid-shard1-hidden-1 standard 3m11s
persistentvolume/pvc-61712454-2038-4692-a6ea-88685d7f34e1 2Gi RWO Delete Bound demo/datadir-mongo-sh-hid-shard1-hidden-0 standard 3m33s
persistentvolume/pvc-9a4fd907-8225-4ed2-90e3-8ca43c0521d2 2Gi RWO Delete Bound demo/datadir-mongo-sh-hid-shard0-hidden-0 standard 3m42s
persistentvolume/pvc-b77cd5d1-d5c1-433b-90dd-3784c5207cd6 2Gi RWO Delete Bound demo/datadir-mongo-sh-hid-shard0-hidden-1 standard 3m20s
KubeDB operator sets the status.phase to Ready 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:
$ kubectl get mg -n demo mongo-sh-hid -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":"mongo-sh-hid","namespace":"demo"},"spec":{"hidden":{"podTemplate":{"spec":{"resources":{"requests":{"cpu":"400m","memory":"400Mi"}}}},"replicas":2,"storage":{"accessModes":["ReadWriteOnce"],"resources":{"requests":{"storage":"2Gi"}},"storageClassName":"standard"}},"shardTopology":{"configServer":{"ephemeralStorage":{},"replicas":3},"mongos":{"replicas":2},"shard":{"ephemeralStorage":{},"replicas":3,"shards":2}},"storageEngine":"inMemory","storageType":"Ephemeral","terminationPolicy":"WipeOut","version":"percona-4.4.10"}}
creationTimestamp: "2022-10-31T05:59:43Z"
finalizers:
- kubedb.com
generation: 3
name: mongo-sh-hid
namespace: demo
resourceVersion: "721561"
uid: 20f66240-669d-4556-b729-f6d0956a9241
spec:
allowedSchemas:
namespaces:
from: Same
authSecret:
name: mongo-sh-hid-auth
autoOps: {}
clusterAuthMode: keyFile
coordinator:
resources: {}
healthChecker:
failureThreshold: 1
periodSeconds: 10
timeoutSeconds: 10
hidden:
podTemplate:
controller: {}
metadata: {}
spec:
affinity:
podAntiAffinity:
preferredDuringSchedulingIgnoredDuringExecution:
- podAffinityTerm:
labelSelector:
matchLabels:
app.kubernetes.io/instance: mongo-sh-hid
app.kubernetes.io/managed-by: kubedb.com
app.kubernetes.io/name: mongodbs.kubedb.com
mongodb.kubedb.com/node.shard: mongo-sh-hid-shard${SHARD_INDEX}
namespaces:
- demo
topologyKey: kubernetes.io/hostname
weight: 100
- podAffinityTerm:
labelSelector:
matchLabels:
app.kubernetes.io/instance: mongo-sh-hid
app.kubernetes.io/managed-by: kubedb.com
app.kubernetes.io/name: mongodbs.kubedb.com
mongodb.kubedb.com/node.shard: mongo-sh-hid-shard${SHARD_INDEX}
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:
memory: 400Mi
requests:
cpu: 400m
memory: 400Mi
replicas: 2
storage:
accessModes:
- ReadWriteOnce
resources:
requests:
storage: 2Gi
storageClassName: standard
keyFileSecret:
name: mongo-sh-hid-key
shardTopology:
configServer:
ephemeralStorage: {}
podTemplate:
controller: {}
metadata: {}
spec:
affinity:
podAntiAffinity:
preferredDuringSchedulingIgnoredDuringExecution:
- podAffinityTerm:
labelSelector:
matchLabels:
app.kubernetes.io/instance: mongo-sh-hid
app.kubernetes.io/managed-by: kubedb.com
app.kubernetes.io/name: mongodbs.kubedb.com
mongodb.kubedb.com/node.config: mongo-sh-hid-configsvr
namespaces:
- demo
topologyKey: kubernetes.io/hostname
weight: 100
- podAffinityTerm:
labelSelector:
matchLabels:
app.kubernetes.io/instance: mongo-sh-hid
app.kubernetes.io/managed-by: kubedb.com
app.kubernetes.io/name: mongodbs.kubedb.com
mongodb.kubedb.com/node.config: mongo-sh-hid-configsvr
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=$MONGO_INITDB_ROOT_PASSWORD --authenticationDatabase=admin
--quiet --eval \"db.adminCommand('ping').ok\" ) -eq \"1\" ]]; then
\n exit 0\n fi\n exit 1"
failureThreshold: 3
periodSeconds: 10
successThreshold: 1
timeoutSeconds: 1
resources:
limits:
memory: 1Gi
requests:
cpu: 500m
memory: 1Gi
serviceAccountName: mongo-sh-hid
replicas: 3
mongos:
podTemplate:
controller: {}
metadata: {}
spec:
affinity:
podAntiAffinity:
preferredDuringSchedulingIgnoredDuringExecution:
- podAffinityTerm:
labelSelector:
matchLabels:
app.kubernetes.io/instance: mongo-sh-hid
app.kubernetes.io/managed-by: kubedb.com
app.kubernetes.io/name: mongodbs.kubedb.com
mongodb.kubedb.com/node.mongos: mongo-sh-hid-mongos
namespaces:
- demo
topologyKey: kubernetes.io/hostname
weight: 100
- podAffinityTerm:
labelSelector:
matchLabels:
app.kubernetes.io/instance: mongo-sh-hid
app.kubernetes.io/managed-by: kubedb.com
app.kubernetes.io/name: mongodbs.kubedb.com
mongodb.kubedb.com/node.mongos: mongo-sh-hid-mongos
namespaces:
- demo
topologyKey: failure-domain.beta.kubernetes.io/zone
weight: 50
lifecycle:
preStop:
exec:
command:
- bash
- -c
- 'mongo admin --username=$MONGO_INITDB_ROOT_USERNAME --password=$MONGO_INITDB_ROOT_PASSWORD
--quiet --eval "db.adminCommand({ shutdown: 1 })" || true'
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=$MONGO_INITDB_ROOT_PASSWORD --authenticationDatabase=admin
--quiet --eval \"db.adminCommand('ping').ok\" ) -eq \"1\" ]]; then
\n exit 0\n fi\n exit 1"
failureThreshold: 3
periodSeconds: 10
successThreshold: 1
timeoutSeconds: 1
resources:
limits:
memory: 1Gi
requests:
cpu: 500m
memory: 1Gi
serviceAccountName: mongo-sh-hid
replicas: 2
shard:
ephemeralStorage: {}
podTemplate:
controller: {}
metadata: {}
spec:
affinity:
podAntiAffinity:
preferredDuringSchedulingIgnoredDuringExecution:
- podAffinityTerm:
labelSelector:
matchLabels:
app.kubernetes.io/instance: mongo-sh-hid
app.kubernetes.io/managed-by: kubedb.com
app.kubernetes.io/name: mongodbs.kubedb.com
mongodb.kubedb.com/node.shard: mongo-sh-hid-shard${SHARD_INDEX}
namespaces:
- demo
topologyKey: kubernetes.io/hostname
weight: 100
- podAffinityTerm:
labelSelector:
matchLabels:
app.kubernetes.io/instance: mongo-sh-hid
app.kubernetes.io/managed-by: kubedb.com
app.kubernetes.io/name: mongodbs.kubedb.com
mongodb.kubedb.com/node.shard: mongo-sh-hid-shard${SHARD_INDEX}
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:
memory: 1Gi
requests:
cpu: 500m
memory: 1Gi
serviceAccountName: mongo-sh-hid
replicas: 3
shards: 2
sslMode: disabled
storageEngine: inMemory
storageType: Ephemeral
terminationPolicy: WipeOut
version: percona-4.4.10
status:
conditions:
- lastTransitionTime: "2022-10-31T05:59:43Z"
message: 'The KubeDB operator has started the provisioning of MongoDB: demo/mongo-sh-hid'
reason: DatabaseProvisioningStartedSuccessfully
status: "True"
type: ProvisioningStarted
- lastTransitionTime: "2022-10-31T06:02:05Z"
message: All desired replicas are ready.
reason: AllReplicasReady
status: "True"
type: ReplicaReady
- lastTransitionTime: "2022-10-31T06:01:47Z"
message: 'The MongoDB: demo/mongo-sh-hid is accepting client requests.'
observedGeneration: 3
reason: DatabaseAcceptingConnectionRequest
status: "True"
type: AcceptingConnection
- lastTransitionTime: "2022-10-31T06:01:47Z"
message: 'The MongoDB: demo/mongo-sh-hid is ready.'
observedGeneration: 3
reason: ReadinessCheckSucceeded
status: "True"
type: Ready
- lastTransitionTime: "2022-10-31T06:02:05Z"
message: 'The MongoDB: demo/mongo-sh-hid is successfully provisioned.'
observedGeneration: 3
reason: DatabaseSuccessfullyProvisioned
status: "True"
type: Provisioned
observedGeneration: 3
phase: Ready
Please note that KubeDB operator has created a new Secret called mongo-sh-hid-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.
Connection Information
Hostname/address: you can use any of these
- Service:
mongo-sh-hid.demo - Pod IP: (
$ kubectl get po -n demo -l mongodb.kubedb.com/node.mongos=mongo-sh-hid-mongos -o yaml | grep podIP)
- Service:
Port:
27017Username: Run following command to get username,
$ kubectl get secrets -n demo mongo-sh-hid-auth -o jsonpath='{.data.\username}' | base64 -d rootPassword: Run the following command to get password,
$ kubectl get secrets -n demo mongo-sh-hid-auth -o jsonpath='{.data.\password}' | base64 -d 6&UiN5;qq)Tnai=7
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 pod -n demo -l mongodb.kubedb.com/node.mongos=mongo-sh-hid-mongos
NAME READY STATUS RESTARTS AGE
mongo-sh-hid-mongos-0 1/1 Running 0 6m38s
mongo-sh-hid-mongos-1 1/1 Running 0 6m20s
$ kubectl exec -it mongo-sh-hid-mongos-0 -n demo bash
mongodb@mongo-sh-mongos-0:/$ mongo admin -u root -p '6&UiN5;qq)Tnai=7'
Percona Server for MongoDB shell version v4.4.10-11
connecting to: mongodb://127.0.0.1:27017/?compressors=disabled&gssapiServiceName=mongodb
Implicit session: session { "id" : UUID("e6979884-81b0-41c9-9745-50654f6fb39b") }
Percona Server for MongoDB server version: v4.4.10-11
Welcome to the Percona Server for MongoDB shell.
For interactive help, type "help".
For more comprehensive documentation, see
https://www.percona.com/doc/percona-server-for-mongodb
Questions? Try the support group
https://www.percona.com/forums/questions-discussions/percona-server-for-mongodb
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("2022-10-31T06:11:39.882Z"),
"logicalSessionTimeoutMinutes" : 30,
"connectionId" : 310,
"maxWireVersion" : 9,
"minWireVersion" : 0,
"topologyVersion" : {
"processId" : ObjectId("635f64d1716935915500369b"),
"counter" : NumberLong(0)
},
"ok" : 1,
"operationTime" : Timestamp(1667196696, 31),
"$clusterTime" : {
"clusterTime" : Timestamp(1667196696, 31),
"signature" : {
"hash" : BinData(0,"q30+hpYp5vn4t5HCvUiw1LDfbTg="),
"keyId" : NumberLong("7160552274547179543")
}
}
}
mongo-sh-hid Shard status,
mongos> sh.status()
--- Sharding Status ---
sharding version: {
"_id" : 1,
"minCompatibleVersion" : 5,
"currentVersion" : 6,
"clusterId" : ObjectId("635f645bf391eaa4fdef2fba")
}
shards:
{ "_id" : "shard0", "host" : "shard0/mongo-sh-hid-shard0-0.mongo-sh-hid-shard0-pods.demo.svc.cluster.local:27017,mongo-sh-hid-shard0-1.mongo-sh-hid-shard0-pods.demo.svc.cluster.local:27017,mongo-sh-hid-shard0-2.mongo-sh-hid-shard0-pods.demo.svc.cluster.local:27017", "state" : 1, "tags" : [ "shard0" ] }
{ "_id" : "shard1", "host" : "shard1/mongo-sh-hid-shard1-0.mongo-sh-hid-shard1-pods.demo.svc.cluster.local:27017,mongo-sh-hid-shard1-1.mongo-sh-hid-shard1-pods.demo.svc.cluster.local:27017,mongo-sh-hid-shard1-2.mongo-sh-hid-shard1-pods.demo.svc.cluster.local:27017", "state" : 1, "tags" : [ "shard1" ] }
active mongoses:
"4.4.10-11" : 2
autosplit:
Currently enabled: yes
balancer:
Currently enabled: yes
Currently running: no
Failed balancer rounds in last 5 attempts: 0
Migration Results for the last 24 hours:
407 : Success
databases:
{ "_id" : "config", "primary" : "config", "partitioned" : true }
config.system.sessions
shard key: { "_id" : 1 }
unique: false
balancing: true
chunks:
shard0 618
shard1 406
too many chunks to print, use verbose if you want to force print
{ "_id" : "kubedb-system", "primary" : "shard0", "partitioned" : true, "version" : { "uuid" : UUID("987e328c-5675-49d7-81a1-25d99142cad1"), "lastMod" : 1 } }
kubedb-system.health-check
shard key: { "id" : 1 }
unique: false
balancing: true
chunks:
shard0 3
shard1 1
{ "id" : { "$minKey" : 1 } } -->> { "id" : 0 } on : shard0 Timestamp(2, 1)
{ "id" : 0 } -->> { "id" : 1 } on : shard0 Timestamp(1, 2)
{ "id" : 1 } -->> { "id" : 2 } on : shard1 Timestamp(2, 0)
{ "id" : 2 } -->> { "id" : { "$maxKey" : 1 } } on : shard0 Timestamp(1, 4)
tag: shard0 { "id" : 0 } -->> { "id" : 1 }
tag: shard1 { "id" : 1 } -->> { "id" : 2 }
As sh.status() command only shows the general members, if we want to assure that hidden-nodes have been added correctly we need to exec into any shard-pod & run rs.conf() command against the admin database. Open another terminal :
kubectl exec -it -n demo pod/mongo-sh-hid-shard1-0 -- bash
root@mongo-sh-hid-shard0-1:/ mongo admin -u root -p '6&UiN5;qq)Tnai=7'
Defaulted container "mongodb" out of: mongodb, copy-config (init)
Percona Server for MongoDB shell version v4.4.10-11
connecting to: mongodb://127.0.0.1:27017/?compressors=disabled&gssapiServiceName=mongodb
Implicit session: session { "id" : UUID("86dadf16-fff2-4483-b3ee-1ca7fc94229f") }
Percona Server for MongoDB server version: v4.4.10-11
Welcome to the Percona Server for MongoDB shell.
For interactive help, type "help".
For more comprehensive documentation, see
https://www.percona.com/doc/percona-server-for-mongodb
Questions? Try the support group
https://www.percona.com/forums/questions-discussions/percona-server-for-mongodb
shard1:PRIMARY> rs.conf()
{
"_id" : "shard1",
"version" : 6,
"term" : 1,
"protocolVersion" : NumberLong(1),
"writeConcernMajorityJournalDefault" : false,
"members" : [
{
"_id" : 0,
"host" : "mongo-sh-hid-shard1-0.mongo-sh-hid-shard1-pods.demo.svc.cluster.local:27017",
"arbiterOnly" : false,
"buildIndexes" : true,
"hidden" : false,
"priority" : 1,
"tags" : {
},
"slaveDelay" : NumberLong(0),
"votes" : 1
},
{
"_id" : 1,
"host" : "mongo-sh-hid-shard1-1.mongo-sh-hid-shard1-pods.demo.svc.cluster.local:27017",
"arbiterOnly" : false,
"buildIndexes" : true,
"hidden" : false,
"priority" : 1,
"tags" : {
},
"slaveDelay" : NumberLong(0),
"votes" : 1
},
{
"_id" : 2,
"host" : "mongo-sh-hid-shard1-2.mongo-sh-hid-shard1-pods.demo.svc.cluster.local:27017",
"arbiterOnly" : false,
"buildIndexes" : true,
"hidden" : false,
"priority" : 1,
"tags" : {
},
"slaveDelay" : NumberLong(0),
"votes" : 1
},
{
"_id" : 3,
"host" : "mongo-sh-hid-shard1-hidden-0.mongo-sh-hid-shard1-pods.demo.svc.cluster.local:27017",
"arbiterOnly" : false,
"buildIndexes" : true,
"hidden" : true,
"priority" : 0,
"tags" : {
},
"slaveDelay" : NumberLong(0),
"votes" : 1
},
{
"_id" : 4,
"host" : "mongo-sh-hid-shard1-hidden-1.mongo-sh-hid-shard1-pods.demo.svc.cluster.local:27017",
"arbiterOnly" : false,
"buildIndexes" : true,
"hidden" : true,
"priority" : 0,
"tags" : {
},
"slaveDelay" : NumberLong(0),
"votes" : 1
}
],
"settings" : {
"chainingAllowed" : true,
"heartbeatIntervalMillis" : 2000,
"heartbeatTimeoutSecs" : 10,
"electionTimeoutMillis" : 10000,
"catchUpTimeoutMillis" : -1,
"catchUpTakeoverDelayMillis" : 30000,
"getLastErrorModes" : {
},
"getLastErrorDefaults" : {
"w" : 1,
"wtimeout" : 0
},
"replicaSetId" : ObjectId("635f645c4883e315f55b07b4")
}
}
Enable sharding to collection songs.list and insert document. See sh.shardCollection(namespace, key, unique, options) for details about shardCollection command.
mongos> sh.enableSharding("songs");
{
"ok" : 1,
"operationTime" : Timestamp(1667197117, 5),
"$clusterTime" : {
"clusterTime" : Timestamp(1667197117, 5),
"signature" : {
"hash" : BinData(0,"PqbGBYWJBwAexJoFMwUEQ1Z+ezc="),
"keyId" : NumberLong("7160552274547179543")
}
}
}
mongos> sh.shardCollection("songs.list", {"myfield": 1});
{
"collectionsharded" : "songs.list",
"collectionUUID" : UUID("ed9c0fec-d488-4a2f-b5ce-8b244676a5b4"),
"ok" : 1,
"operationTime" : Timestamp(1667197139, 14),
"$clusterTime" : {
"clusterTime" : Timestamp(1667197139, 14),
"signature" : {
"hash" : BinData(0,"Cons7FRJzPPeysmanMLyNgJlwNk="),
"keyId" : NumberLong("7160552274547179543")
}
}
}
mongos> use songs
switched to db songs
mongos> db.list.insert({"led zeppelin": "stairway to heaven", "slipknot": "psychosocial"});
WriteResult({ "nInserted" : 1 })
mongos> db.list.insert({"pink floyd": "us and them", "nirvana": "smells like teen spirit", "john lennon" : "imagine" });
WriteResult({ "nInserted" : 1 })
mongos> db.list.find()
{ "_id" : ObjectId("635f68e774b0bd92060ebeb6"), "led zeppelin" : "stairway to heaven", "slipknot" : "psychosocial" }
{ "_id" : ObjectId("635f692074b0bd92060ebeb7"), "pink floyd" : "us and them", "nirvana" : "smells like teen spirit", "john lennon" : "imagine" }
Run sh.status() to see whether the songs database has sharding enabled, and the primary shard for the songs database.
The Sharded Collection section sh.status.databases.<collection> provides information on the sharding details for sharded collection(s) (E.g. songs.list). 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("635f645bf391eaa4fdef2fba")
}
shards:
{ "_id" : "shard0", "host" : "shard0/mongo-sh-hid-shard0-0.mongo-sh-hid-shard0-pods.demo.svc.cluster.local:27017,mongo-sh-hid-shard0-1.mongo-sh-hid-shard0-pods.demo.svc.cluster.local:27017,mongo-sh-hid-shard0-2.mongo-sh-hid-shard0-pods.demo.svc.cluster.local:27017", "state" : 1, "tags" : [ "shard0" ] }
{ "_id" : "shard1", "host" : "shard1/mongo-sh-hid-shard1-0.mongo-sh-hid-shard1-pods.demo.svc.cluster.local:27017,mongo-sh-hid-shard1-1.mongo-sh-hid-shard1-pods.demo.svc.cluster.local:27017,mongo-sh-hid-shard1-2.mongo-sh-hid-shard1-pods.demo.svc.cluster.local:27017", "state" : 1, "tags" : [ "shard1" ] }
active mongoses:
"4.4.10-11" : 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:
513 : Success
databases:
{ "_id" : "config", "primary" : "config", "partitioned" : true }
config.system.sessions
shard key: { "_id" : 1 }
unique: false
balancing: true
chunks:
shard0 512
shard1 512
too many chunks to print, use verbose if you want to force print
{ "_id" : "kubedb-system", "primary" : "shard0", "partitioned" : true, "version" : { "uuid" : UUID("987e328c-5675-49d7-81a1-25d99142cad1"), "lastMod" : 1 } }
kubedb-system.health-check
shard key: { "id" : 1 }
unique: false
balancing: true
chunks:
shard0 3
shard1 1
{ "id" : { "$minKey" : 1 } } -->> { "id" : 0 } on : shard0 Timestamp(2, 1)
{ "id" : 0 } -->> { "id" : 1 } on : shard0 Timestamp(1, 2)
{ "id" : 1 } -->> { "id" : 2 } on : shard1 Timestamp(2, 0)
{ "id" : 2 } -->> { "id" : { "$maxKey" : 1 } } on : shard0 Timestamp(1, 4)
tag: shard0 { "id" : 0 } -->> { "id" : 1 }
tag: shard1 { "id" : 1 } -->> { "id" : 2 }
{ "_id" : "songs", "primary" : "shard1", "partitioned" : true, "version" : { "uuid" : UUID("03c7f9c8-f30f-42a4-8505-7f58fb95d3f3"), "lastMod" : 1 } }
songs.list
shard key: { "myfield" : 1 }
unique: false
balancing: true
chunks:
shard1 1
{ "myfield" : { "$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.anothercollection.insert({"myfield": "ccc", "otherfield": "this is non sharded", "kube" : "db" });
WriteResult({ "nInserted" : 1 })
mongos> db.anothercollection.insert({"myfield": "aaa", "more": "field" });
WriteResult({ "nInserted" : 1 })
mongos> db.anothercollection.find()
{ "_id" : ObjectId("635f69c674b0bd92060ebeb8"), "myfield" : "ccc", "otherfield" : "this is non sharded", "kube" : "db" }
{ "_id" : ObjectId("635f69d574b0bd92060ebeb9"), "myfield" : "aaa", "more" : "field" }
Now, eventually sh.status()
mongos> sh.status()
--- Sharding Status ---
sharding version: {
"_id" : 1,
"minCompatibleVersion" : 5,
"currentVersion" : 6,
"clusterId" : ObjectId("635f645bf391eaa4fdef2fba")
}
shards:
{ "_id" : "shard0", "host" : "shard0/mongo-sh-hid-shard0-0.mongo-sh-hid-shard0-pods.demo.svc.cluster.local:27017,mongo-sh-hid-shard0-1.mongo-sh-hid-shard0-pods.demo.svc.cluster.local:27017,mongo-sh-hid-shard0-2.mongo-sh-hid-shard0-pods.demo.svc.cluster.local:27017", "state" : 1, "tags" : [ "shard0" ] }
{ "_id" : "shard1", "host" : "shard1/mongo-sh-hid-shard1-0.mongo-sh-hid-shard1-pods.demo.svc.cluster.local:27017,mongo-sh-hid-shard1-1.mongo-sh-hid-shard1-pods.demo.svc.cluster.local:27017,mongo-sh-hid-shard1-2.mongo-sh-hid-shard1-pods.demo.svc.cluster.local:27017", "state" : 1, "tags" : [ "shard1" ] }
active mongoses:
"4.4.10-11" : 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:
513 : Success
databases:
{ "_id" : "config", "primary" : "config", "partitioned" : true }
config.system.sessions
shard key: { "_id" : 1 }
unique: false
balancing: true
chunks:
shard0 512
shard1 512
too many chunks to print, use verbose if you want to force print
{ "_id" : "demo", "primary" : "shard1", "partitioned" : false, "version" : { "uuid" : UUID("040d4dc2-232f-4cc8-bae0-11c79244a9a7"), "lastMod" : 1 } }
{ "_id" : "kubedb-system", "primary" : "shard0", "partitioned" : true, "version" : { "uuid" : UUID("987e328c-5675-49d7-81a1-25d99142cad1"), "lastMod" : 1 } }
kubedb-system.health-check
shard key: { "id" : 1 }
unique: false
balancing: true
chunks:
shard0 3
shard1 1
{ "id" : { "$minKey" : 1 } } -->> { "id" : 0 } on : shard0 Timestamp(2, 1)
{ "id" : 0 } -->> { "id" : 1 } on : shard0 Timestamp(1, 2)
{ "id" : 1 } -->> { "id" : 2 } on : shard1 Timestamp(2, 0)
{ "id" : 2 } -->> { "id" : { "$maxKey" : 1 } } on : shard0 Timestamp(1, 4)
tag: shard0 { "id" : 0 } -->> { "id" : 1 }
tag: shard1 { "id" : 1 } -->> { "id" : 2 }
{ "_id" : "songs", "primary" : "shard1", "partitioned" : true, "version" : { "uuid" : UUID("03c7f9c8-f30f-42a4-8505-7f58fb95d3f3"), "lastMod" : 1 } }
songs.list
shard key: { "myfield" : 1 }
unique: false
balancing: true
chunks:
shard1 1
{ "myfield" : { "$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 shard0.
Cleaning up
To cleanup the Kubernetes resources created by this tutorial, run:
kubectl delete -n demo mg/mongo-sh-hid
kubectl delete ns demo
Next Steps
- 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.