During my last project I was setting up a Release Pipeline in VSTS and one of the steps was to create a Sharded MongoDB in Cosmos DB.
I am a big fan of the Azure CLI, which I use quiet often.
I started to create in bash an Azure CLI script but soon I discovered that it was not working well. The script gave no errors, everything seemed to be ok, but I was getting an error when inserting a document that the sharded key was not found/provided.
I created a stackoverflow thread to describe the problem.
After having contact with Microsoft they confirmed there’s indeed a bug in the actual version of the Azure CLI (2.0.21) and to solve the problem the partition (shard) key string should use the “$v” pattern to make everything working.
So here is the final working bash script to be able to create a sharded MongoDB:
The important part is actually this:
partition="/'\$v'/YourShardID/'\$v'"
Where /YourShardID should be replaced with the document property you want to use for the partitioning.
Conclusion
Use the “$v” pattern described above to define you partition, until Microsoft will come with a new release of the Azure CLI with a fix.