DEV Community

Cover image for Deploying a MongoDB Collection Generator on Kubernetes
Dmitry Romanoff
Dmitry Romanoff

Posted on

Deploying a MongoDB Collection Generator on Kubernetes

Creating a utility to generate 100 MongoDB collections, each populated with 1 million random documents, and deploying it on Kubernetes involves several steps. This guide walks through the process, from setting up a Kubernetes environment to generating the collections and deploying the job in a dedicated namespace.

Deploying a MongoDB Collection Generator on Kubernetes

1. Setting Up Your Kubernetes Environment

Ensure you have a Kubernetes cluster (such as GKE, EKS, AKS, or Minikube) and configure kubectl to connect to it.

2. Create a Dedicated Namespace

To keep this deployment isolated, create a namespace called my-lab:

kubectl create namespace my-lab kubectl get ns my-lab 
Enter fullscreen mode Exit fullscreen mode

3. Deploy MongoDB on Kubernetes

Create a Persistent Volume (PV)

Create a mongo-pv.yaml file to define a persistent volume for MongoDB data:

apiVersion: v1 kind: PersistentVolume metadata: name: mongo-pv namespace: my-lab spec: capacity: storage: 10Gi accessModes: - ReadWriteOnce hostPath: path: /data/mongo 
Enter fullscreen mode Exit fullscreen mode

Apply the PV:

kubectl apply -f mongo-pv.yaml 
Enter fullscreen mode Exit fullscreen mode

Create a Persistent Volume Claim (PVC)

Define a persistent volume claim in mongo-pvc.yaml:

apiVersion: v1 kind: PersistentVolumeClaim metadata: name: mongo-pvc namespace: my-lab spec: accessModes: - ReadWriteOnce resources: requests: storage: 10Gi 
Enter fullscreen mode Exit fullscreen mode

Apply the PVC:

kubectl apply -f mongo-pvc.yaml 
Enter fullscreen mode Exit fullscreen mode

Create a MongoDB Deployment

Define the MongoDB deployment and service in mongo-deployment.yaml:

apiVersion: apps/v1 kind: Deployment metadata: name: mongo namespace: my-lab spec: replicas: 1 selector: matchLabels: app: mongo template: metadata: labels: app: mongo spec: containers: - name: mongo image: mongo:latest ports: - containerPort: 27017 env: - name: MONGO_INITDB_ROOT_USERNAME value: "root" - name: MONGO_INITDB_ROOT_PASSWORD value: "password" volumeMounts: - name: mongo-storage mountPath: /data/db volumes: - name: mongo-storage persistentVolumeClaim: claimName: mongo-pvc --- apiVersion: v1 kind: Service metadata: name: mongo namespace: my-lab spec: type: ClusterIP ports: - port: 27017 targetPort: 27017 selector: app: mongo 
Enter fullscreen mode Exit fullscreen mode

Apply the deployment:

kubectl apply -f mongo-deployment.yaml 
Enter fullscreen mode Exit fullscreen mode

4. Connect to MongoDB

Verify the MongoDB deployment by connecting to it:

kubectl exec -it <mongo-pod-name> -n my-lab -- mongosh -u root -p password 
Enter fullscreen mode Exit fullscreen mode

5. Verify Persistence

Scale down and then back up the MongoDB deployment to ensure data persists:

kubectl scale deployment mongo --replicas=0 -n my-lab kubectl scale deployment mongo --replicas=1 -n my-lab 
Enter fullscreen mode Exit fullscreen mode

6. Create a Python Utility for Collection Generation

Using Python, define a script to create collections and populate them with random documents:

import random import string import pymongo from pymongo import MongoClient def random_string(length=10): return ''.join(random.choices(string.ascii_letters + string.digits, k=length)) def create_collections_and_populate(db_name='mydatabase', collections_count=100, documents_per_collection=1_000_000): client = MongoClient('mongodb://root:password@mongo:27017/') db = client[db_name] for i in range(collections_count): collection_name = f'collection_{i+1}' collection = db[collection_name] print(f'Creating collection: {collection_name}') bulk_data = [{'name': random_string(), 'value': random.randint(1, 100)} for _ in range(documents_per_collection)] collection.insert_many(bulk_data) print(f'Inserted {documents_per_collection} documents into {collection_name}') if __name__ == "__main__": create_collections_and_populate() 
Enter fullscreen mode Exit fullscreen mode

7. Dockerize the Python Utility

Create a Dockerfile to containerize the Python script:

FROM python:3.9-slim WORKDIR /app COPY mongo_populator.py . RUN pip install pymongo CMD ["python", "mongo_populator.py"] 
Enter fullscreen mode Exit fullscreen mode

Build and push the image to a container registry:

docker build -t <your-docker-repo>/mongo-populator:latest . docker push <your-docker-repo>/mongo-populator:latest 
Enter fullscreen mode Exit fullscreen mode

8. Create a Kubernetes Job

Define a job in mongo-populator-job.yaml to run the collection generation script:

apiVersion: batch/v1 kind: Job metadata: name: mongo-populator namespace: my-lab spec: template: spec: containers: - name: mongo-populator image: <your-docker-repo>/mongo-populator:latest env: - name: MONGO_URI value: "mongodb://root:password@mongo:27017/" restartPolicy: Never backoffLimit: 4 
Enter fullscreen mode Exit fullscreen mode

Apply the job:

kubectl apply -f mongo-populator-job.yaml 
Enter fullscreen mode Exit fullscreen mode

9. Verify Collection Generation

After the job completes, connect to MongoDB to examine the data:

kubectl exec -it <mongo-pod-name> -n my-lab -- mongosh -u root -p password 
Enter fullscreen mode Exit fullscreen mode

In MongoDB:

use mydatabase show collections db.collection_9.find().limit(5).pretty() db.getCollectionNames().forEach(function(collection) { var count = db[collection].countDocuments(); print(collection + ": " + count + " documents"); }); 
Enter fullscreen mode Exit fullscreen mode

Each collection should contain 1 million documents, confirming that the data generation job was successful.

Top comments (0)