Overview

Cosmos Doc Manager takes MongoDB documents and makes them available in Azure Cosmos DB following the format specified by Mongo Connector. It piggybacks on Mongo Replica Set Oplog and is intended for near-realtime synchronizations. Currently it works for Cosmos DB SQL API. Partial MongoDB updates are handled with Stored Procedures and support the following operations.

Disclaimer

The software in this repository is provided AS IS, with no guarantees of any kind. This project is an independent effort and is NOT associated with Microsoft. Having said that, Pull Requests are most welcome.

Prerequisites

• You must have Python installed. Python 3 is recommended.
• Mongo Connector operates on a Mongo Replica Set. Docker is the easiest way to spin it up locally.
• For local testing, install Azure Cosmos DB Emulator. Cosmos DB Emulator currently only supports SQL API.

Local Mongo Replica Set

Run this to spin up a volume-mounted, single-node Mongo Replica Set;

docker run -it --rm -p 27017:27017 -v $HOME/mongodb:/data mongo --replSet myreplicaset

Replica Set needs to be initialized and re-configured because by default Mongo assigns container’s inner address as host. Run this from Mongo Shell;

rs.initiate(); 
conf = rs.conf();
conf.members[0].host = '127.0.0.1:27017';
rs.reconfig(conf, {force:true});

Installation

• Install Mongo Connector sudo pip install mongo-connector
• Clone this repo git clone https://github.com/syedhassaanahmed/cosmos_doc_manager.git
• Let Mongo Connector locate our Doc Manager cd cosmos_doc_manager && export PYTHONPATH=.
• Disable HTTPS Certificate warning export PYTHONWARNINGS="ignore:Unverified HTTPS request"

Run locally

mongo-connector -c config.json

Mongo Connector‘s custom configuration is specified here.

Below JSON is an example config file to sync data in Graph format with Cosmos DB Emulator.

{
  "mainAddress": "localhost:27017",
  "docManagers": [
    {
      "docManager": "cosmos_doc_manager",
      "targetURL": "https://localhost:8081",
      "bulkSize": 100,
      "args": {
        "masterKey": "C2y6yDjf5/R+ob0N8A7Cgv30VRDJIWEHLM+4QDU5DE2nQ9nDuVTqobD4b8mGGyPMbIZnqyMsEcaGQy67XIw/Jw=="
      }
    }
  ]
}

Future improvements

• Support for partitioned collections
• Support for other Cosmos DB APIs