Overview

Building cloud-native applications like Azure Functions and Durable Functions is powerful, but deploying code directly to the cloud without local testing is risky, costly, and slows down development. Local testing is a critical step in ensuring quality, reliability, and speed when developing cloud applications.

Why Run Azure Functions Locally?

Running Azure Functions on your own machine—before you ever deploy to the cloud—comes with a ton of benefits for developers. Here’s why it’s such a good idea:

1. Get Fast Feedback

  • Instant results: See what’s working (and what isn’t) right away, so you can catch errors and bugs early.
  • No waiting: No need to wait for Azure to spin up cloud resources every time you make a change.
  • Boosts productivity: Quick feedback lets you fix issues and try new ideas much faster.

2. Save Money

  • No cloud charges: Running everything locally means you aren’t paying Azure every time you test your code.
  • Less waste: Only deploy when you’re ready, which keeps you from accidentally using up cloud resources.

3. Easier Debugging & Diagnostics

  • Powerful debugging tools: Set breakpoints, watch variables, and dig into the details right on your computer.
  • More control: Troubleshooting is simpler because you have full visibility and control in your local environment.

4. Consistency with Production

  • Mimics the cloud: The local runtime emulates Azure Functions, so your code runs just like it would after deployment.
  • Catch configuration issues early: Test your settings, bindings, and app configs locally, so there are no surprises in production.

5. Better Team Collaboration

  • Easy to share: Everyone on your team can run and test the same code on their own machines, making it easier to reproduce bugs.
  • Confident code reviews: When you review each other’s code, you’re testing it in the same way it will run for real users.

Bottom line:
Running Azure Functions locally makes development faster, cheaper, and more reliable—while making life easier for you and your team.

Using Azurite

When developing Azure Functions or cloud applications that interact with Azure Storage (like Queues, Tables, and Blobs), you need a way to simulate Azure Storage services locally. This lets you develop and test your apps without needing a live Azure subscription or incurring costs.

Azurite is the current open-source emulator for Azure Storage provided by Microsoft.

  • It allows you to run Blob, Queue, and Table storage services locally on your machine.
  • Azurite is cross-platform (works on Windows, macOS, and Linux).
  • You can install it via npm (npm install -g azurite) or use it as a Docker container. there are also other ways but for this javascript example the best way

It has key features which allows you to quicken your local development and testing. It supports most APIs and features needed for Azure Functions and general app development. Also it is actively maintained by Microsoft.

Common Local Testing Scenarios

There are common scenarios you can use Azurite

  • HTTP Trigger Functions: Call your endpoints from Postman, curl, or browser.
  • Queue/Blob Triggers: Use the local storage emulator to simulate Azure Storage events.
  • Durable Orchestrations: Start orchestrations, check state, and replay workflows locally.

Using Azure Storage Explorer with Azurite

One of the cool features you have is to combine Azure Storeage Explorer

Azure Storage Explorer is a free, cross-platform GUI tool from Microsoft that lets you easily manage Azure Storage accounts and resources like blobs, queues, and tables. It can connect not only to live Azure resources, but also to local storage emulators—like Azurite.

The reason why to use this in combination is:

  • Visual Management: Browse, create, upload, and download blobs, queues, and tables in your local Azurite instance using a user-friendly interface.
  • Faster Debugging: Instantly view and manipulate your local storage data during development and testing.
  • Consistency: The same tool and workflow for both local (Azurite) and cloud storage.

How to Connect Azure Storage Explorer to Azurite

  1. Start Azurite Locally

    azurite

    By default, Azurite will listen on:

    • Blob service: http://127.0.0.1:10000
    • Queue service: http://127.0.0.1:10001
    • Table service: http://127.0.0.1:10002

  2. Open Azure Storage Explorer

  3. Add a New Connection

    • Click the plug icon or “Add Account” (or right-click “Local & Attached” → “Storage Accounts” → “Connect to Azure Storage”).
    • Select “Attach to a local emulator”.
    • Choose Azurite.

  4. Confirm Connection

    • Storage Explorer will auto-fill the default Azurite connection details.
    • Click Next and then Connect.

  5. Explore Your Local Storage

    • You’ll now see your local Azurite storage accounts (such as devstoreaccount1) and their blobs, queues, and tables.
    • You can upload, download, edit, or delete data just as you would with a real Azure account.

Sample Connection Details for Azurite

If you need to manually enter connection details, use:

  • Account Name: devstoreaccount1
  • Account Key: Eby8vdM02xNOcqFlqUwJPLlmEtlCDXJ1OUzFT50uSRZ6IFsuFq2UVErCz4I6tq/K1SZFPTOtr/KBHBeksoGMGw==
  • Blob Service Endpoint: http://127.0.0.1:10000/devstoreaccount1
  • Queue Service Endpoint: http://127.0.0.1:10001/devstoreaccount1
  • Table Service Endpoint: http://127.0.0.1:10002/devstoreaccount1

Summary

  • Azure Storage Explorer + Azurite = Seamless, powerful local Azure Storage development.
  • Manage your local emulated storage visually, just as you do with real Azure resources.
  • Perfect for rapid prototyping, debugging, and learning—no cloud subscription needed!