Azure Examples: Cosmos DB and Mongoose

This repository shows how to use Cosmos DB with Node.js and the MongoDB protocol with the popular mongoose npm package.

create a Cosmos DB account and database using Azure CLI
code examples with mongoose library
cost-optimized examples with mongoose discriminators

Example Demo Output:

$ npm run simple-examples

> node examples/simple/run.js

[INFO] Connected (…)
[INFO] Number of Families: 4
[INFO] New Family saved (…)
[INFO] Number of Families: 5
[INFO] Disconnected, bye bye

Azure Cost Optimization

By default Mongoose creates a new colleciton per model. Because Azure charges you per collection, it makes sense to use mongoose discriminators to leverage schema inheritance to optimize costs:

Then you only pay once for the Base model collection instaead of doubling costs for Family and Vacation models.

For more details see the cost optimized examples →

Usage

Step 1 - Create a Cosmos DB (Azure CLI)

Set Resource Names for Reuse

N.B. Cosmos DB account names must be globally unique

export COSMOS_DEMO_ACCOUNT_NAME=mycosmosdb-demo
export COSMOS_DEMO_RG_NAME=mycosmosdb-demo-rg

Create Cosmos DB Account

Free Tier: is limited to 1 account per subscription. Remove --enable-free-tier if required
Enable Aggregation Pipeline for mongoose's rich API, so we can use e.g. db.collection.countDocuments()

az cosmosdb create \
    --name $COSMOS_DEMO_ACCOUNT_NAME \
    --resource-group $COSMOS_DEMO_RG_NAME \
    --kind MongoDB \
    --capabilities EnableAggregationPipeline \
    --enable-free-tier true

Create Database

We will name ours mongodemo

az cosmosdb mongodb database create \
    --resource-group $COSMOS_DEMO_RG_NAME \
    --account-name $COSMOS_DEMO_ACCOUNT_NAME \
    --name mongodemo

Get Secret Key

Note: jq is used to parse JSON output from Azure CLI and is pre-installed on Azure DevOps hosted ubuntu agents.

az cosmosdb keys list \
    --name $COSMOS_DEMO_ACCOUNT_NAME \
    --resource-group $COSMOS_DEMO_RG_NAME \
    | jq '.primaryMasterKey' | sed 's/"//g'

Step 2 - Get Code

First you need the code in this repository

git clone https://github.com/julie-ng/cosmosdb-mongoose-example

Step 3 - Configure Credentials

To test your connection locally, copy .env.example and rename it to .env filling in your configuration, for example

# .env
DB_HOST=mycosmosdb.documents.azure.com
DB_USER=mycosmosdb
DB_PASSWORD=myaccountprimarykey
DB_NAME=mydbname
DB_PORT=10255

Final Step - run the examples

npm install
npm run simple-examples
npm run optimized-examples

Misc.

New to JavaScript?

Don't worry. These examples are easy to follow. But just in case, you need some guidance:

Promises and Async/Await
To run multiple examples with a single connection, we have to add some extra Promises. See details at ./examples/README.md →
ES6 Modules
Compared to the official Microsoft documentation, each operation is split into its own file, e.g. family.add.js.

Learn about ES6 modules here on MSN →

Have fun exploring the examples. If you have any questions, open an issue →