Connect to mongodb with mongoose both in kubernetes - docker

Question

I have a microservice which I developed and tested using docker-compose. Now I would like to deploy it to kubernetes.
Part of my docker-compose file looks like this:
tasksdb:
container_name: tasks-db
image: mongo:4.4.1
restart: always
ports:
- '6004:27017'
volumes:
- ./tasks_service/tasks_db:/data/db
networks:
- backend
tasks-service:
container_name: tasks-service
build: ./tasks_service
restart: always
ports:
- "5004:3000"
volumes:
- ./tasks_service/logs:/usr/src/app/logs
- ./tasks_service/tasks_attachments/:/usr/src/app/tasks_attachments
depends_on:
- tasksdb
networks:
- backend
I used mongoose to connect to the database and it worked fine:
const connection = "mongodb://tasks-db:27017/tasks";
const connectDb = () => {
mongoose.connect(connection, {useNewUrlParser:true, useCreateIndex:true, useFindAndModify: false});
return mongoose.connect(connection);
};
Utilizing Kompose, I created a deployment file however I had to modify the persistent volume and persistent volume claim accordingly.
I have something like this:
apiVersion: v1
kind: PersistentVolume
metadata:
name: tasks-volume
labels:
type: local
spec:
storageClassName: manual
volumeMode: Filesystem
capacity:
storage: 10Gi
accessModes:
- ReadWriteMany
nfs:
server: 192.168.60.50
path: /tasks_db
---
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
name: tasksdb-claim0
spec:
storageClassName: manual
accessModes:
- ReadWriteMany
resources:
requests:
storage: 1Gi
I changed the mongourl as shown here like this:
const connection = "mongodb://tasksdb.default.svc.cluster.local:27017/tasks";
My deployment looks like this:
apiVersion: v1
items:
- apiVersion: v1
kind: Service
metadata:
annotations:
kompose.cmd: kompose convert -f docker-compose.yml -o k8manifest.yml
kompose.version: 1.22.0 (955b78124)
creationTimestamp: null
labels:
io.kompose.service: tasks-service
name: tasks-service
spec:
ports:
- name: "5004"
port: 5004
targetPort: 3000
selector:
io.kompose.service: tasks-service
status:
loadBalancer: {}
- apiVersion: v1
kind: Service
metadata:
annotations:
kompose.cmd: kompose convert -f docker-compose.yml -o k8manifest.yml
kompose.version: 1.22.0 (955b78124)
creationTimestamp: null
labels:
io.kompose.service: tasksdb
name: tasksdb
spec:
ports:
- name: "6004"
port: 6004
targetPort: 27017
selector:
io.kompose.service: tasksdb
status:
loadBalancer: {}
- apiVersion: apps/v1
kind: Deployment
metadata:
annotations:
kompose.cmd: kompose convert -f docker-compose.yml -o k8manifest.yml
kompose.version: 1.22.0 (955b78124)
creationTimestamp: null
labels:
io.kompose.service: tasks-service
name: tasks-service
spec:
replicas: 1
selector:
matchLabels:
io.kompose.service: tasks-service
strategy:
type: Recreate
template:
metadata:
annotations:
kompose.cmd: kompose convert -f docker-compose.yml -o k8manifest.yml
kompose.version: 1.22.0 (955b78124)
creationTimestamp: null
labels:
io.kompose.service: tasks-service
spec:
containers:
- image: 192.168.60.50:5000/blascal_tasks-service
name: tasks-service
imagePullPolicy: IfNotPresent
ports:
- containerPort: 3000
restartPolicy: Always
status: {}
- apiVersion: apps/v1
kind: Deployment
metadata:
annotations:
kompose.cmd: kompose convert -f docker-compose.yml -o k8manifest.yml
kompose.version: 1.22.0 (955b78124)
creationTimestamp: null
labels:
io.kompose.service: tasksdb
name: tasksdb
spec:
replicas: 1
selector:
matchLabels:
io.kompose.service: tasksdb
strategy:
type: Recreate
template:
metadata:
annotations:
kompose.cmd: kompose convert -f docker-compose.yml -o k8manifest.yml
kompose.version: 1.22.0 (955b78124)
creationTimestamp: null
labels:
io.kompose.service: tasksdb
spec:
containers:
- image: mongo:4.4.1
name: tasks-db
ports:
- containerPort: 27017
resources: {}
volumeMounts:
- mountPath: /data/db
name: tasksdb-claim0
restartPolicy: Always
volumes:
- name: tasksdb-claim0
persistentVolumeClaim:
claimName: tasksdb-claim0
status: {}
Having several services I added an ingress resource for my routing:
apiVersion: networking.k8s.io/v1beta1
kind: Ingress
metadata:
name: test-ingress
annotations:
kubernetes.io/ingress.class: nginx
nginx.ingress.kubernetes.io/use-regex: "true"
nginx.ingress.kubernetes.io/rewrite-target: /
spec:
rules:
- http:
paths:
- path: /
pathType: Prefix
backend:
serviceName: tasks-service
servicePort: 5004
The deployment seems to run fine as you can see .
However, I have three issues:
Despite the fact that I can hit my default path which just reads "tasks service is up" I cannot access my mongoose routes like /api/task/raise which connects to the db, it says "..buffering timed out" like . I guess, the path does not link up to the database service?
the tasks service pod gives this
Whenever there is a power surge and my machine goes off, bringing up the db deployment fails until I delete the config files from the persistent volume, how do I prevent this corruption of files?
I have been researching in an elaborate way of changing the master ip of my cluster as I intend to transfer my cluster to a different network. Any guidance please?
kubectl logs --namespace=kube-system -l k8s-app=kube-dns
the above gives this :

Answer 1

Your tasksdb Service exposes port 6004, not 27017. Try using the following URL:
const connection = "mongodb://tasksdb.default.svc.cluster.local:6004/tasks";
Changing your network depends on what networking CNI plugin you are using. Every plugin has different steps . For Calico please see https://docs.projectcalico.org/networking/migrate-pools

Answer 2

I believe this is your cluster ip setting for mongodb instance:
apiVersion: v1
kind: Service
metadata:
annotations:
kompose.cmd: kompose convert -f docker-compose.yml -o k8manifest.yml
kompose.version: 1.22.0 (955b78124)
creationTimestamp: null
labels:
io.kompose.service: tasksdb
name: tasksdb
spec:
ports:
- name: "6004"
port: 6004
targetPort: 27017
selector:
io.kompose.service: tasksdb
status:
loadBalancer: {}
When you create an instance of mongodb inside kubernetes, it runs inside a pod. To connect to a pod, we have to go through the cluster IP service. Anytime we are trying to connect to a cluster IP service we are going to write the name of that cluster iP service for the domain of connection url. in this case you connection url must be
mongodb://tasksdb:6004/nameOfDatabase