I have deployed MongoDB ReplicaSet on Kubernetes using Helm and the chart stable/mongodb-replicaset
On Kubernetes, I can connect to MongoDB using the connection string which is something of the sort
mongodb://mongodb0.example.com:27017,mongodb1.example.com:27017,mongodb2.example.com:27017/?replicaSet=myReplIn the event I change the number of replicas, the connection string would change as well, which also means that every application connecting to the database would need to be updated.
Is there a workaround to this?
I thought of creating a Service, so that only this would need to be changed, however the connection string does not pass regex validation.
Any help on this is appreciated.
The drivers will discover all nodes of a replica set automatically. If you are only changing the total number but the first one always has the same address, you can specify just the first node's address in the connection string.
Depending on the driver this may or may not connect to the replica set (as opposed directly to that one node), which generally has two solutions:
Alternatively, you can set up SRV records and use an SRV URI which is how MongoDB Atlas works. This applies to all topologies (including sharded clusters, which replica set discovery does not apply to).
The Helm chart stable/mongodb-replicaset deploys also 2 headless services:
<release name>-mongodb-replicaset<release name>-mongodb-replicaset-clientThe DNS record of <release name>-mongodb-replicaset returns the address of all the replicas, so, in order to connect to the replicaset, the connection string is
"mongodb+srv://<release name>-mongodb-replicaset.namespace.svc.cluster.local/?tls=false&ssl=false"
Note that tls and ssl have been set to false for testing as they were enabled by default.