New to KubeDB? Please start here.

Initializing with Script

This guide will show you how to to create database and initialize script with MongoDB Schema Manager using Schema Manager Operator.

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.

• Install KubeDB in your cluster following the steps here.

• Install KubeVault in your cluster following the steps here.

• You should be familiar with the following concepts:

  • MongoDB
  • MongoDBDatabase
  • Schema Manager Overview
  • Stash Overview
  • KubeVault Overview

To keep everything isolated, we are going to use a separate namespace called demo throughout this tutorial.

$ kubectl create ns demo
namespace/demo created

Note: YAML files used in this tutorial are stored in docs/guides/mongodb/schema-manager/initializing-with-script/yamls directory of kubedb/doc repository.

Deploy MongoDB Server and Vault Server

Here, we are going to deploy a MongoDB Server by using KubeDB operator. Also, we are deploying a Vault Server using KubeVault Operator.

Deploy MongoDB Server

In this section, we are going to deploy a MongoDB Server. Let’s deploy it using this following yaml,

apiVersion: kubedb.com/v1
kind: MongoDB
metadata:
  name: mongodb
  namespace: demo
spec:
  allowedSchemas:
    namespaces:
      from: Selector
      selector:
        matchExpressions:
        - {key: kubernetes.io/metadata.name, operator: In, values: [dev]}
    selector:
      matchLabels:
        "schema.kubedb.com": "mongo"
  version: "4.4.26"
  replicaSet:
    name: "replicaset"
  podTemplate:
    spec:
      containers:
      - name: mongo
        resources:
          requests:
            cpu: "100m"
            memory: "100Mi"
  replicas: 3
  storageType: Durable
  storage:
    storageClassName: "standard"
    accessModes:
      - ReadWriteOnce
    resources:
      requests:
        storage: 100Mi
  deletionPolicy: WipeOut

Here,

• spec.version is the name of the MongoDBVersion CR. Here, we are using MongoDB version 4.4.26.
• spec.storageType specifies the type of storage that will be used for MongoDB. It can be Durable or Ephemeral. The default value of this field is Durable. If Ephemeral is used then KubeDB will create the MongoDB using EmptyDir volume.
• spec.storage specifies the StorageClass of PVC dynamically allocated to store data for this database. This storage spec will be passed to the PetSet 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.
• spec.allowedSchemas specifies the namespace and selectors of allowed Schema Manager.
• spec.deletionPolicy specifies what KubeDB should do when a user try to delete the operation of MongoDB CR. Wipeout means that the database will be deleted without restrictions. It can also be “Halt”, “Delete” and “DoNotTerminate”. Learn More about these HERE.

Let’s save this yaml configuration into mongodb.yaml Then create the above MongoDB CR

$ kubectl apply -f mongodb.yaml 
mongodb.kubedb.com/mongodb created

Deploy Vault Server

In this section, we are going to deploy a Vault Server. Let’s deploy it using this following yaml,

apiVersion: kubevault.com/v1alpha1
kind: VaultServer
metadata:
  name: vault
  namespace: demo
spec:
  version: 1.8.2
  replicas: 3
  allowedSecretEngines:
    namespaces:
      from: All
    secretEngines:
      - mongodb
  unsealer:
    secretShares: 5
    secretThreshold: 3
    mode:
      kubernetesSecret:
        secretName: vault-keys
  backend:
    raft:
      path: "/vault/data"
      storage:
        storageClassName: "standard"
        resources:
          requests:
            storage: 1Gi
  authMethods:
    - type: kubernetes
      path: kubernetes
  terminationPolicy: WipeOut

Here,

• spec.version is a required field that specifies the original version of Vault that has been used to build the docker image specified in spec.vault.image field.
• spec.replicas specifies the number of Vault nodes to deploy. It has to be a positive number.
• spec.allowedSecretEngines defines the types of Secret Engines & the Allowed namespaces from where a SecretEngine can be attached to the VaultServer.
• spec.unsealer is an optional field that specifies Unsealer configuration. Unsealer handles automatic initializing and unsealing of Vault.
• spec.backend is a required field that specifies the Vault backend storage configuration. KubeVault operator generates storage configuration according to this spec.backend.
• spec.authMethods is an optional field that specifies the list of auth methods to enable in Vault.
• spec.deletionPolicy is an optional field that gives flexibility whether to nullify(reject) the delete operation of VaultServer crd or which resources KubeVault operator should keep or delete when you delete VaultServer crd.

Let’s save this yaml configuration into vault.yaml Then create the above VaultServer CR

$ kubectl apply -f vault.yaml
vaultserver.kubevault.com/vault created

Create Separate Namespace For Schema Manager

In this section, we are going to create a new Namespace and we will only allow this namespace for our Schema Manager. Below is the YAML of the Namespace that we are going to create,

apiVersion: v1
kind: Namespace
metadata:
  name: dev
  labels:
    kubernetes.io/metadata.name: dev

Let’s save this yaml configuration into namespace.yaml. Then create the above Namespace,

$ kubectl apply -f namespace.yaml
namespace/dev created

Script with ConfigMap

apiVersion: v1
kind: ConfigMap
metadata:
  name: test-script
  namespace: dev
data:
  init.js: |-
    use initdb;
    db.product.insert({"name" : "KubeDB"});    

$ kubectl apply -f test-script.yaml 
configmap/test-script created

Deploy Schema Manager Initialize with Script

Here, we are going to deploy Schema Manager with the new Namespace that we have created above. Let’s deploy it using this following yaml,

apiVersion: schema.kubedb.com/v1alpha1
kind: MongoDBDatabase
metadata:
  name: sample-script
  namespace: dev
  labels:
    "schema.kubedb.com": "mongo"
spec:
  database:
    serverRef:
      name: mongodb
      namespace: demo
    config:
      name: initdb
  vaultRef:
    name: vault
    namespace: demo
  accessPolicy:
    subjects:
      - name: "saname"
        namespace: dev
        kind: "ServiceAccount"
        apiGroup: ""
    defaultTTL: "5m"
    maxTTL: "200h"
  init:
    initialized: false
    script:
      scriptPath: "/etc/config"
      configMap:
        name: "test-script"
      podTemplate:
        spec:
          containers:
            - env:
              - name: "HAVE_A_TRY"
                value: "whoo! It works"
              name: cnt
              image: nginx
              command:
               - /bin/sh
               - -c
              args:
               - ls
  deletionPolicy: Delete

Here,

• spec.database is a required field specifying the database server reference and the desired database configuration.
• spec.vaultRef is a required field that specifies which KubeVault server to use for user management.
• spec.accessPolicy is a required field that specifies the access permissions like which service account or cluster user have the access and also for how long they can access through it.
• spec.init is an optional field, containing the information of a script or a snapshot using which the database should be initialized during creation.
• spec.init.script refers to the information regarding the .js file which should be used for initialization.
• spec.init.script.scriptPath accepts a directory location at which the operator should mount the .js file.
• spec.init.script.podTemplate specifies pod-related details, like environment variables, arguments, images etc.
• spec.deletionPolicy is an optional field that gives flexibility whether to nullify (reject) the delete operation.

Let’s save this yaml configuration into sample-script.yaml and apply it,

$ kubectl apply -f sample-script.yaml 
mongodbdatabase.schema.kubedb.com/sample-script created

Let’s check the STATUS of Schema Manager,

$ kubectl get mongodbdatabase -A
NAMESPACE   NAME            DB_SERVER   DB_NAME   STATUS    AGE
dev         sample-script   mongodb     initdb    Current   56s

Here,

In STATUS section, Current means that the current Secret of Schema Manager is vaild, and it will automatically Expired after it reaches the limit of defaultTTL that we’ve defined in the above yaml.

Now, let’s get the secret name from schema-manager, and get the login credentials for connecting to the database,

$ kubectl get mongodbdatabase sample-script -n dev -o=jsonpath='{.status.authSecret.name}'
sample-script-mongo-req-98k0ch

$ kubectl view-secret -n dev sample-script-mongo-req-98k0ch -a
password=-e4v396GFjjjMgPPuU7q
username=v-kubernetes-demo-k8s-f7695915-1e-6sXNTvVpPDtueRQWvoyH-1662641233

Verify Initialization

Here, we are going to connect to the database with the login credentials and verify the database initialization,

$ kubectl exec -it -n demo mongodb-0 -c mongodb -- bash
root@mongodb-0:/# mongo --authenticationDatabase=initdb --username='v-kubernetes-demo-k8s-f7695915-1e-6sXNTvVpPDtueRQWvoyH-1662641233' --password='-e4v396GFjjjMgPPuU7q' initdb
MongoDB shell version v4.4.26
...

replicaset:PRIMARY> show dbs
initdb  0.000GB

replicaset:PRIMARY> show collections
product

replicaset:PRIMARY> db.product.find()
{ "_id" : ObjectId("6319e46f950868e7b3476cdf"), "name" : "KubeDB" }

replicaset:PRIMARY> exit
bye

Now, Let’s check the STATUS of Schema Manager again,

$ kubectl get mongodbdatabase -A
NAMESPACE   NAME            DB_SERVER   DB_NAME   STATUS    AGE
dev         sample-script   mongodb     initdb    Expired   6m

Here, we can see that the STATUS of the schema-manager is Expired because it’s exceeded defaultTTL: "5m", which means the current Secret of Schema Manager isn’t vaild anymore. Now, if we try to connect and login with the credentials that we have acquired before from schema-manager, it won’t work.

$ kubectl exec -it -n demo mongodb-0 -c mongodb -- bash
root@mongodb-0:/# mongo --authenticationDatabase=initdb --username='v-kubernetes-demo-k8s-f7695915-1e-6sXNTvVpPDtueRQWvoyH-1662641233' --password='-e4v396GFjjjMgPPuU7q' initdb
MongoDB shell version v4.4.26
connecting to: mongodb://127.0.0.1:27017/initdb?authSource=initdb&compressors=disabled&gssapiServiceName=mongodb
Error: Authentication failed. :
connect@src/mongo/shell/mongo.js:374:17
@(connect):2:6
exception: connect failed
exiting with code 1
root@mongodb-0:/# exit
exit

We can’t connect to the database with the login credentials, which is Expired. We will not be able to access the database even though we’re in the middle of a connected session.

Cleaning Up

To clean up the Kubernetes resources created by this tutorial, run:

$ kubectl delete ns dev
$ kubectl delete ns demo

Next Steps

• Detail concepts of MongoDBDatabase object.
• Go through the concepts of KubeVault.
• Detail concepts of MongoDB object.
• Detail concepts of MongoDBVersion object.