1 - Should have good experience in managing mongodb sharded cluster (cluster with more than 20 shards or dealing with atleast 10TB of data)
2 - Should have experience in Ansible for upgrading / installing mongodb across multiple shards
3 - Should be able to manage cluster preferably without using ops manager (Includes backups, restore replication, scaling cluster etc)
4 - Knowledge of mongo queries for analysing slow queries and providing suggestions
5 Should know to use tools for monitoring resource usage in the cluster
6 - Preferable to have basic shell scripting skills