FailedToSatisfyReadPreference: Could not find host matching read preference { mode: "primary" } - mongodb

Question

I want to use mongodb-shard for my project. I created a helm chart https://github.com/b-rohit/mongodb-shard-chart to deploy to kubernetes cluster.
I use kind cluster running locally to test it. The config and shard servers are running properly. I am able to execute commands in their mongo shells. The mongos server is not able to connect to the replica set in config server. I get following error message in mongos
2020-04-17T13:33:31.579+0000 W SHARDING [replSetDistLockPinger] pinging failed for distributed lock pinger :: caused by :: FailedToSatisfyReadPreference: Could not find host matching read preference { mode: "primary" } for set mongors1conf
2020-04-17T13:33:31.579+0000 W SHARDING [mongosMain] Error initializing sharding state, sleeping for 2 seconds and trying again :: caused by :: FailedToSatisfyReadPreference: Error loading clusterID :: caused by :: Could not find host matching read preference { mode: "nearest" } for set mongors1conf
2020-04-17T13:33:31.579+0000 I SHARDING [shard-registry-reload] Periodic reload of shard registry failed :: caused by :: FailedToSatisfyReadPreference: could not get updated shard list from config server :: caused by :: Could not find host matching read preference { mode: "nearest" } for set mongors1conf; will retry after 30s
On config server logs are following
2020-04-17T13:33:11.578+0000 I NETWORK [listener] connection accepted from 10.244.0.6:34400 #5 (1 connection now open)
2020-04-17T13:33:11.578+0000 I NETWORK [conn5] received client metadata from 10.244.0.6:34400 conn5: { driver: { name: "NetworkInterfaceTL", version: "4.2.5" }, os: { type: "Linux", name: "Ubuntu", architecture: "x86_64", version: "18.04" } }
2020-04-17T13:33:11.589+0000 I ACCESS [conn5] Successfully authenticated as principal __system on local from client 10.244.0.6:34400
2020-04-17T13:33:38.197+0000 I SHARDING [replSetDistLockPinger] Marking collection config.lockpings as collection version: <unsharded>
2020-04-17T13:33:38.202+0000 W SHARDING [replSetDistLockPinger] pinging failed for distributed lock pinger :: caused by :: LockStateChangeFailed: findAndModify query predicate didn't match any lock document
2020-04-17T13:44:39.743+0000 I CONTROL [LogicalSessionCacheRefresh] Failed to create config.system.sessions: Cannot create config.system.sessions until there are shards, will try again at the next refresh interval
2020-04-17T13:44:39.743+0000 I CONTROL [LogicalSessionCacheRefresh] Sessions collection is not set up; waiting until next sessions refresh interval: Cannot create config.system.sessions until there are shards
2020-04-17T13:44:39.743+0000 I SH_REFR [ConfigServerCatalogCacheLoader-1] Refresh for collection config.system.sessions took 0 ms and found the collection is not sharded
2020-04-17T13:44:39.743+0000 I CONTROL [LogicalSessionCacheReap] Sessions collection is not set up; waiting until next sessions reap interval: Collection config.system.sessions is not sharded.
2020-04-17T13:44:42.570+0000 I NETWORK [conn5] end connection 10.244.0.10:37922 (0 connections now open)
I am new to mongodb. It took lot of time to put this chart together. I checked other similar questions also. could not find host matching read preferences in mongodb
I am not able to debug it further.

Answer 1

Your config server replica set is either:
not running (not all nodes are up)
not a replica set (replSetInitiate not executed, or failed)
is referenced from the shard nodes incorrectly (wrong host, ip or wrong replica set name)
is up and running but your shards aren't allowed to access it due to firewall rules
Ensure you can access the replica set nodes from mongo shell from the machines on which the shard mongods are running.