At the moment I have a mongo cluster with two slaves and a master runing on docker host1:27017, host2:27018, host3:27018 the current version is 3.4.1
My idea was to add one replicaset into my k8s infra, wait for sync, add a second one, wait for sync, add a third one and then kill the old ones.
Not seems that simple, first of all can I do this migrating from 3.4.1 to 4.0.9 or will I have problems with the replication ?
I made some tests in local doing
docker run -p 27017:27017 mongo:4.0 mongod --replSet rs0 --bind_ip localhost,host1But I have the folowing error
Failed to set up listener: SocketException: Cannot assign requested addressIf you have any idea how to do that, or just let me know if I am going into the good direction :)
If you are not familar with mongodb-replicaset, I recommend to use mongodb-replicaset helm charts directly.
For me, the configuration of mongodb-replicaset helm charts is too completed. So I just create statefulset, then init replicaset manually.
First, create statefuleset and service.
apiVersion: v1
kind: Service
metadata:
name: mongo-rs-headless
spec:
type: ClusterIP
clusterIP: None
selector:
app: mongo-rs-pod
ports:
- name: http
port: 27017
protocol: TCP
targetPort: mongo
---
apiVersion: apps/v1beta1
kind: StatefulSet
metadata:
name: mongo-rs-sts
spec:
serviceName: mongo-rs-headless
replicas: 3
updateStrategy:
type: OnDelete
template:
metadata:
labels:
app: mongo-rs-pod
spec:
terminationGracePeriodSeconds: 10
containers:
- name: compute
image: mongo:3-stretch
imagePullPolicy: IfNotPresent
command:
- mongod
- --dbpath=/data/db
- --port=27017
- --bind_ip=0.0.0.0
- --replSet=rs1
ports:
- name: mongo
containerPort: 27017
volumeMounts:
- name: mongo-data
mountPath: /data/db
livenessProbe:
exec:
command:
- mongo
- --eval
- "db.adminCommand('ping')"
initialDelaySeconds: 30
timeoutSeconds: 5
failureThreshold: 3
periodSeconds: 30
successThreshold: 1
readinessProbe:
exec:
command:
- mongo
- --eval
- "db.adminCommand('ping')"
initialDelaySeconds: 5
timeoutSeconds: 1
failureThreshold: 3
periodSeconds: 20
successThreshold: 1
volumes:
- name: mongo-data
emptyDir: {}Then, attach into one of the mongo-rs-pod, login into mongo shell, execute:
rs.initiate({_id: "rs1", members: [
{ _id : 0, host : "mongo-rs-pod-0.mongo-rs-headless.default.svc.cluster.local" },
{ _id : 1, host : "mongo-rs-pod-1.mongo-rs-headless.default.svc.cluster.local" },
{ _id : 2, host : "mongo-rs-pod-2.mongo-rs-headless.default.svc.cluster.local" }
]})