Maximizing Database Connectivity in Azure Functions with Javascript

Question

Maximizing Database Connectivity in Azure Functions with Javascript

I'm having trouble finding clear guidelines on how to handle database connections (specifically MongoDB) in an Azure function written in JavaScript.

According to a Microsoft document linked below, it's advised not to create a new connection for each invocation of the function. Instead, static variables in C# with .NET Framework Data Provider for SQL Server can be used, as client connection pooling is handled automatically. However, it doesn't explain how to apply this in JavaScript.

https://learn.microsoft.com/en-us/azure/azure-functions/manage-connections

One solution mentioned is to create a global variable to store the database client between invocations, although the author expresses uncertainty about whether this is the correct approach.

Has anyone implemented this method in a production environment or can provide insight on whether it's the right way to go?

javascript mongodb mongoose azure-functions

Answer 1

Answer №1

Indeed, there is a striking resemblance between the approach of storing a single SqlConnection instance in a static variable in C#/SQL and storing a single Db instance in a global variable in JS/MongoDB. When working with Azure Functions, the recommended pattern for JS/MongoDB is as follows (assuming familiarity with async/await - although callbacks can also be used as mentioned in the linked article):

// getDb.js

let dbInstance;

module.exports = async function() {
    if (!dbInstance) {
        dbInstance = await MongoClient.connect(uri);
    }
    return dbInstance;
};

// function.js

const getDb = require('./getDb.js');

module.exports = async function(context, trigger) {
    let db = await getDb();
    // ... perform operations with db ..
};

By following this approach, you ensure that only one Db object is instantiated per host instance. It's important to note that this is not one per Function App - in the case of a dedicated App Service Plan, the number of instances will align with what is specified in the plan. Conversely, in a Consumption Plan, it will vary based on the app's activity level.

Answer 2

Indeed, there is a striking resemblance between the approach of storing a single SqlConnection instance in a static variable in C#/SQL and storing a single Db instance in a global variable in JS/MongoDB. When working with Azure Functions, the recommended pattern for JS/MongoDB is as follows (assuming familiarity with async/await - although callbacks can also be used as mentioned in the linked article):

// getDb.js

let dbInstance;

module.exports = async function() {
    if (!dbInstance) {
        dbInstance = await MongoClient.connect(uri);
    }
    return dbInstance;
};

// function.js

const getDb = require('./getDb.js');

module.exports = async function(context, trigger) {
    let db = await getDb();
    // ... perform operations with db ..
};

By following this approach, you ensure that only one Db object is instantiated per host instance. It's important to note that this is not one per Function App - in the case of a dedicated App Service Plan, the number of instances will align with what is specified in the plan. Conversely, in a Consumption Plan, it will vary based on the app's activity level.

Maximizing Database Connectivity in Azure Functions with Javascript

Answer №1

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