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:
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| #!/bin/bash | |
| resourceGroupName="cosmosdbshardedtest" | |
| name="mongodboncosmosdb" | |
| databaseName="mongodb" | |
| collectionName="mongodbcoll" | |
| kind="MongoDB" | |
| partition="/'\$v'/YourShardID/'\$v'" | |
| az login | |
| az group create –name $resourceGroupName –location westeurope | |
| az cosmosdb create –name $name –kind $kind –resource-group $resourceGroupName | |
| az cosmosdb database create –name $name –db-name $databaseName –resource-group $resourceGroupName | |
| az cosmosdb collection create –collection-name $collectionName –name $name –db-name $databaseName –resource-group $resourceGroupName –partition-key-path $partition |
The important part is actually this:
partition="/'$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.
Marco Mansi's Blog 
Great article! I wan’t to establish sharding in Azure cosmosdb. As i’m using it as mongo wrapper in cloud. Could please point me into right direction?
Thanks a lot
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