Day11 as #100DaysofMongoDB as 100daysofcode
Starting a pattern today for the next 10 days n I hope I keep up with it.
Calling it Day11 as First Day of using MongoDB in a kubernetes deployment.
Kubernetes is an orchestration framework which allows you to scale, automate and manage containerised application.
By Containerised, means, to bundle and package the application in one and run on a cloud or different deployment.
This is fir for modern applications which are based on Microservice architectures, have frequent deployments or statefulsets.
Let’s see a sample deployment where MongoDB is deployed in Kubernetes with a creation of replica sets.
The statefulsets and deployments are two ways through which the MongoDB can be deployed in a kubernetes environment.
The difference occurs when:
1. Deployment model: This is preferred when a stateless application is preferred. All the pods of the application use the same volume specified in the deployment.yaml files. The pod names are deployed with a different name every-time the pod is deleted.
2. Statefulset model : This deployment is preferred when each pod of the deployment used its own independent set and volume. The pods here are deployed with the same name every-time the pods are deleted.
Each deployment of the application has config-map and secrets which contains non-sensitive data and sensitive data respectively.
Deploying MongoDB as Deployment
- Creating a Secret:
apiVersion: v1
data:
password: cGFzc3dvcmQxMjM= #Encoded with Base64 (password)
username: YWRtaW51c2Vy #Encoded with Base64 (password)
kind: Secret
metadata:
creationTimestamp: null
name: mongo-creds
- Creating a deployement.yaml file
apiVersion: apps/v1
kind: Deployment
metadata:
labels:
app: mongo
name: mongo
spec:
replicas: 1
selector:
matchLabels:
app: mongo
strategy: {}
template:
metadata:
labels:
app: mongo
spec:
containers:
- image: mongo
name: mongo
args: ["--dbpath","/data/db"]
livenessProbe:
exec:
command:
- mongo
- --disableImplicitSessions
- --eval
- "db.adminCommand('ping')"
initialDelaySeconds: 30
periodSeconds: 10
timeoutSeconds: 5
successThreshold: 1
failureThreshold: 6
readinessProbe:
exec:
command:
- mongo
- --disableImplicitSessions
- --eval
- "db.adminCommand('ping')"
initialDelaySeconds: 30
periodSeconds: 10
timeoutSeconds: 5
successThreshold: 1
failureThreshold: 6
env:
- name: MONGO_INITDB_ROOT_USERNAME
valueFrom:
secretKeyRef:
name: mongo-creds
key: username
- name: MONGO_INITDB_ROOT_PASSWORD
valueFrom:
secretKeyRef:
name: mongo-creds
key: password
volumeMounts:
- name: "mongo-data-dir"
mountPath: "/data/db"
volumes:
- name: "mongo-data-dir"
persistentVolumeClaim:
claimName: "mongo-data"
Specifying a few key value pairs defined above:
kind: Deployment.. defines the applications is of type deployment.
replicas : 1 specifics that the application will have only one replica pod.
livenessProbe: To make sure that the pods are not stuck and are redeployed after the timeouts mentioned.
Persistent Volumes: is a storage provisioned by the admin
Persistent volume Chains: Works for a dynamic volume provisioning enabled system
Once the deployments and service files created with
kubectl create -f deployment.yaml/service.yaml files
Once the pods are up and running the deployment will look like the following:
aasawari.sahasrabuddhe@Aasawaris-MacBook-Pro mongodb % kubectl get all
NAME READY STATUS RESTARTS AGE
pod/mongo-cd755c96f-67sc8 1/1 Running 0 6d
pod/mongo-client-6c7bc768c4-bp5hq 1/1 Running 0 6d
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
service/kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 6d7h
service/mongo-nodeport-svc NodePort 10.101.236.24 <none> 27017:32000/TCP 6d
NAME READY UP-TO-DATE AVAILABLE AGE
deployment.apps/mongo 1/1 1 1 6d
deployment.apps/mongo-client 1/1 1 1 6d
NAME DESIRED CURRENT READY AGE
replicaset.apps/mongo-cd755c96f 1 1 1 6d
replicaset.apps/mongo-client-6c7bc768c4 1 1 1 6d
aasawari.sahasrabuddhe@Aasawaris-MacBook-Pro mongodb %
In-order to login to the database
kubectl exec deployment/mongo-client -it – /bin/bash
mongo --host mongo-nodeport-svc --port 27017 -u adminuser -p password123
Deploying MongoDB as Statefulset
Creating ststefulset.yaml and service.yaml files deploying MongoDB as deployment files:
statefulset.yaml:
apiVersion: apps/v1
kind: StatefulSet. #Defining the MongoDB deployment as statefulset
metadata:
name: mongo
spec:
selector:
matchLabels:
app: mongo
serviceName: "mongo"
replicas: 4. #Three copies of MongoDB pods will be deployed.
template:
metadata:
labels:
app: mongo
spec:
terminationGracePeriodSeconds: 10. #When pod is deleted, it will take this time to terminate
containers:
- name: mongo
image: mongo
command:
- mongod
- "--bind_ip_all". #Allowing MongoDB to allow all IPs
- "--replSet"
- rs0
ports:
- containerPort: 27017. # Defining port
volumeMounts:
- name: mongo-volume
mountPath: /data/db
volumeClaimTemplates:
- metadata:
name: mongo-volume
spec:
accessModes: [ "ReadWriteOnce" ]
resources:
requests:
storage: 1Gi
service.yaml file:
apiVersion: v1
kind: Service
metadata:
name: mongo
labels:
app: mongo
spec:
ports:
- name: mongo
port: 27017
targetPort: 27017
clusterIP: None
selector:
app: mongo
After kubectl create -f . The deployment will look like the following:
aasawari.sahasrabuddhe@Aasawaris-MacBook-Pro mongodb % kubectl get all
NAME READY STATUS RESTARTS AGE
pod/mongo-0 1/1 Running 0 2d5h
pod/mongo-1 1/1 Running 0 2d5h
pod/mongo-2 1/1 Running 0 2d5h
pod/mongo-3 1/1 Running 0 6h20m
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
service/mongo ClusterIP None <none> 27017/TCP 2d5h
NAME READY AGE
statefulset.apps/mongo 4/4 2d5h
aasawari.sahasrabuddhe@Aasawaris-MacBook-Pro mongodb %
You can exec to any of the 4 MongoDB commands using
kubectl exec -it <pod-name> mongo or mongosh
and explore the databases and perform various operations.
Will be discussing MongoDB deployment for the next 10 days in this sections of #100DaysOfMongoDB
Thanks
Aasawari
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