Develop Azure Functions by using Visual Studio Code

The Azure Functions extension for Visual Studio Code lets you locally develop functions and deploy them to Azure. If this experience is your first with Azure Functions, you can learn more at An introduction to Azure Functions.

The Azure Functions extension provides these benefits:

  • Edit, build, and run functions on your local development computer.
  • Publish your Azure Functions project directly to Azure.
  • Write your functions in various languages while taking advantage of the benefits of Visual Studio Code.

The extension can be used with the following languages, which are supported by the Azure Functions runtime starting with version 2.x:

*Requires that you set C# script as your default project language.

In this article, examples are currently available only for JavaScript (Node.js) and C# class library functions.

This article provides details about how to use the Azure Functions extension to develop functions and publish them to Azure. Before you read this article, you should create your first function by using Visual Studio Code.

Important

Don't mix local development and portal development for a single function app. When you publish from a local project to a function app, the deployment process overwrites any functions that you developed in the portal.

Prerequisites

Run local requirements

These prerequisites are only required to run and debug your functions locally. They aren't required to create or publish projects to Azure Functions.

  • The Azure Functions Core Tools version 2.x or later. The Core Tools package is downloaded and installed automatically when you start the project locally. Core Tools includes the entire Azure Functions runtime, so download and installation might take some time.

  • The C# extension for Visual Studio Code.

  • .NET Core CLI tools.

Create an Azure Functions project

The Functions extension lets you create a function app project, along with your first function. The following steps show how to create an HTTP-triggered function in a new Functions project. HTTP trigger is the simplest function trigger template to demonstrate.

    1. Choose the Azure icon in the Activity bar, then in the Workspace (local) area, select the + button, choose Create Function in the dropdown. When prompted, choose Create new project.

    Screenshot of create a new project window.

  1. Choose the directory location for your project workspace and choose Select. You should either create a new folder or choose an empty folder for the project workspace. Don't choose a project folder that is already part of a workspace.

  2. When prompted, Select a language for your project, and if necessary choose a specific language version.

  3. Select the HTTP trigger function template, or you can select Skip for now to create a project without a function. You can always add a function to your project later.

    Screenshot for selecting H T T P trigger.

  4. Type HttpExample for the function name and select Enter, and then select Function authorization. This authorization level requires you to provide a function key when you call the function endpoint.

    Screenshot for creating function authorization.

  5. From the dropdown list, select Add to workspace.

     Screenshot for selectIng Add to workplace.

  6. In Do you trust the authors of the files in this folder? window, select Yes.

    Screenshot to confirm trust in authors of the files.

  7. A function is created in your chosen language and in the template for an HTTP-triggered function.

    Screenshot for H T T P-triggered function template in Visual Studio Code.

Generated project files

The project template creates a project in your chosen language and installs required dependencies. For any language, the new project has these files:

  • host.json: Lets you configure the Functions host. These settings apply when you're running functions locally and when you're running them in Azure. For more information, see host.json reference.

  • local.settings.json: Maintains settings used when you're running functions locally. These settings are used only when you're running functions locally. For more information, see Local settings file.

    Important

    Because the local.settings.json file can contain secrets, you need to exclude it from your project source control.

Depending on your language, these other files are created:

At this point, you can add input and output bindings to your function. You can also add a new function to your project.

Install binding extensions

Except for HTTP and timer triggers, bindings are implemented in extension packages. You must install the extension packages for the triggers and bindings that need them. The process for installing binding extensions depends on your project's language.

Run the dotnet add package command in the Terminal window to install the extension packages that you need in your project. The following example demonstrates how you add a binding for an in-process class library:

dotnet add package Microsoft.Azure.WebJobs.Extensions.<BINDING_TYPE_NAME> --version <TARGET_VERSION>

The following example demonstrates how you add a binding for an isolated-process class library:

dotnet add package Microsoft.Azure.Functions.Worker.Extensions.<BINDING_TYPE_NAME> --version <TARGET_VERSION>

In either case, replace <BINDING_TYPE_NAME> with the name of the package that contains the binding you need. You can find the desired binding reference article in the list of supported bindings.

Replace <TARGET_VERSION> in the example with a specific version of the package, such as 3.0.0-beta5. Valid versions are listed on the individual package pages at NuGet.org. The major versions that correspond to Functions runtime 1.x or 2.x are specified in the reference article for the binding.

Add a function to your project

You can add a new function to an existing project by using one of the predefined Functions trigger templates. To add a new function trigger, select F1 to open the command palette, and then search for and run the command Azure Functions: Create Function. Follow the prompts to choose your trigger type and define the required attributes of the trigger. If your trigger requires an access key or connection string to connect to a service, get it ready before you create the function trigger.

The results of this action depend on your project's language:

A new C# class library (.cs) file is added to your project.

Connect to services

You can connect your function to other Azure services by adding input and output bindings. Bindings connect your function to other services without you having to write the connection code. The process for adding bindings depends on your project's language. To learn more about bindings, see Azure Functions triggers and bindings concepts.

The following examples connect to a storage queue named outqueue, where the connection string for the storage account is set in the MyStorageConnection application setting in local.settings.json.

Update the function method to add the following parameter to the Run method definition:

[Queue("outqueue"),StorageAccount("AzureWebJobsStorage")] ICollector<string> msg,

The msg parameter is an ICollector<T> type, which represents a collection of messages that are written to an output binding when the function completes. The following code adds a message to the collection:

// Add a message to the output collection.
msg.Add(name);

Messages are sent to the queue when the function completes.

To learn more, see the Queue storage output binding reference article documentation. To learn more in general about which bindings can be added to a function, see Add bindings to an existing function in Azure Functions.

Sign in to Azure

Before you can publish your app, you must sign in to Azure.

  1. If you aren't already signed in, choose the Azure icon in the Activity bar. Then in the Resources area, choose Sign in to Azure....

    Screenshot of the sign-in to Azure window within VS Code.

    If you're already signed in and can see your existing subscriptions, go to the next section. If you don't yet have an Azure account, choose Create and Azure Account.... Students can choose Create and Azure for Students Account....

  2. When prompted in the browser, choose your Azure account and sign in using your Azure account credentials. If you create a new account, you can sign in after your account is created.

  3. After you've successfully signed in, you can close the new browser window. The subscriptions that belong to your Azure account are displayed in the sidebar.

Create Azure resources

Before you can publish your Functions project to Azure, you must have a function app and related resources in your Azure subscription to run your code. The function app provides an execution context for your functions. When you publish to a function app in Azure from Visual Studio Code, the project is packaged and deployed to the selected function app in your Azure subscription.

When you create a function app in Azure, you can choose either a quick function app create path using defaults or an advanced path. This way you'll have more control over the remote resources created.

Quick function app create

In this section, you create a function app and related resources in your Azure subscription.

  1. Choose the Azure icon in the Activity bar. Then in the Resources area, select the + icon and choose the Create Function App in Azure option.

    Create a resource in your Azure subscription

  2. Provide the following information at the prompts:

    Prompt Selection
    Select subscription Choose the subscription to use. You won't see this prompt when you have only one subscription visible under Resources.
    Enter a globally unique name for the function app Type a name that is valid in a URL path. The name you type is validated to make sure that it's unique in Azure Functions.
    Select a runtime stack Choose the language version on which you've been running locally.
    Select a location for new resources For better performance, choose a region near you.

    The extension shows the status of individual resources as they're being created in Azure in the Azure: Activity Log panel.

    Log of Azure resource creation

  3. When the creation is complete, the following Azure resources are created in your subscription. The resources are named based on your function app name:

    • A resource group, which is a logical container for related resources.
    • A standard Azure Storage account, which maintains state and other information about your projects.
    • A function app, which provides the environment for executing your function code. A function app lets you group functions as a logical unit for easier management, deployment, and sharing of resources within the same hosting plan.
    • An App Service plan, which defines the underlying host for your function app.
    • An Application Insights instance connected to the function app, which tracks usage of your functions in the app.

    A notification is displayed after your function app is created and the deployment package is applied.

    Tip

    By default, the Azure resources required by your function app are created based on the function app name you provide. By default, they're also created in the same new resource group with the function app. If you want to either customize the names of these resources or reuse existing resources, you need to publish the project with advanced create options instead.

Publish a project to a new function app in Azure by using advanced options

The following steps publish your project to a new function app created with advanced create options:

  1. In the command pallet, enter Azure Functions: Create function app in Azure...(Advanced).

  2. If you're not signed in, you're prompted to Sign in to Azure. You can also Create a free Azure account. After signing in from the browser, go back to Visual Studio Code.

  3. Following the prompts, provide this information:

    Prompt Selection
    Enter a globally unique name for the new function app. Type a globally unique name that identifies your new function app and then select Enter. Valid characters for a function app name are a-z, 0-9, and -.
    Select a runtime stack. Choose the language version on which you've been running locally.
    Select an OS. Choose either Linux or Windows. Python apps must run on Linux.
    Select a resource group for new resources. Choose Create new resource group and type a resource group name, like myResourceGroup, and then select enter. You can also select an existing resource group.
    Select a location for new resources. Select a location in a region near you or near other services that your functions access.
    Select a hosting plan. Choose Consumption for serverless Consumption plan hosting, where you're only charged when your functions run.
    Select a storage account. Choose Create new storage account and at the prompt, type a globally unique name for the new storage account used by your function app and then select Enter. Storage account names must be between 3 and 24 characters long and can contain only numbers and lowercase letters. You can also select an existing account.
    Select an Application Insights resource for your app. Choose Create new Application Insights resource and at the prompt, type a name for the instance used to store runtime data from your functions.

    A notification appears after your function app is created and the deployment package is applied. Select View Output in this notification to view the creation and deployment results, including the Azure resources that you created.

Get the URL of an HTTP triggered function in Azure

To call an HTTP-triggered function from a client, you need the URL of the function when it's deployed to your function app. This URL includes any required function keys. You can use the extension to get these URLs for your deployed functions. If you just want to run the remote function in Azure, use the Execute function now functionality of the extension.

  1. Select F1 to open the command palette, and then search for and run the command Azure Functions: Copy Function URL.

  2. Follow the prompts to select your function app in Azure and then the specific HTTP trigger that you want to invoke.

The function URL is copied to the clipboard, along with any required keys passed by the code query parameter. Use an HTTP tool to submit POST requests, or a browser for GET requests to the remote function.

When the extension gets the URL of functions in Azure, it uses your Azure account to automatically retrieve the keys it needs to start the function. Learn more about function access keys. Starting non-HTTP triggered functions requires using the admin key.

Deploy project files

We recommend setting-up continuous deployment so that your function app in Azure is updated when you update source files in the connected source location. You can also deploy your project files from Visual Studio Code.

When you publish from Visual Studio Code, you take advantage of the Zip deploy technology.

Important

Deploying to an existing function app always overwrites the contents of that app in Azure.

  1. Choose the Azure icon in the Activity bar, then in the Workspace area, select your project folder and select the Deploy... button.

    Deploy project from the Visual Studio Code workspace

  2. Select Deploy to Function App..., choose the function app you just created, and select Deploy.

  3. After deployment completes, select View Output to view the creation and deployment results, including the Azure resources that you created. If you miss the notification, select the bell icon in the lower right corner to see it again.

    Screenshot of the View Output window.

Run functions

The Azure Functions extension lets you run individual functions. You can run functions either in your project on your local development computer or in your Azure subscription.

For HTTP trigger functions, the extension calls the HTTP endpoint. For other kinds of triggers, it calls administrator APIs to start the function. The message body of the request sent to the function depends on the type of trigger. When a trigger requires test data, you're prompted to enter data in a specific JSON format.

Run functions in Azure.

To execute a function in Azure from Visual Studio Code.

  1. In the command pallet, enter Azure Functions: Execute function now and choose your Azure subscription.

  2. Choose your function app in Azure from the list. If you don't see your function app, make sure you're signed in to the correct subscription.

  3. Choose the function you want to run from the list and type the message body of the request in Enter request body. Press Enter to send this request message to your function. The default text in Enter request body should indicate the format of the body. If your function app has no functions, a notification error is shown with this error.

  4. When the function executes in Azure and returns a response, a notification is raised in Visual Studio Code.

You can also run your function from the Azure: Functions area by right-clicking (Ctrl-clicking on Mac) the function you want to run from your function app in your Azure subscription and choosing Execute Function Now....

When you run your functions in Azure from Visual Studio Code, the extension uses your Azure account to automatically retrieve the keys it needs to start the function. Learn more about function access keys. Starting non-HTTP triggered functions requires using the admin key.

Run functions locally

The local runtime is the same runtime that hosts your function app in Azure. Local settings are read from the local.settings.json file. To run your Functions project locally, you must meet more requirements.

Configure the project to run locally

The Functions runtime uses an Azure Storage account internally for all trigger types other than HTTP and webhooks. So you need to set the Values.AzureWebJobsStorage key to a valid Azure Storage account connection string.

This section uses the Azure Storage extension for Visual Studio Code with Azure Storage Explorer to connect to and retrieve the storage connection string.

To set the storage account connection string:

  1. In Visual Studio, open Cloud Explorer, expand Storage Account > Your Storage Account, and then select Properties and copy the Primary Connection String value.

  2. In your project, open the local.settings.json file and set the value of the AzureWebJobsStorage key to the connection string you copied.

  3. Repeat the previous step to add unique keys to the Values array for any other connections required by your functions.

For more information, see Local settings file.

Debug functions locally

To debug your functions, select F5. If you haven't already downloaded Core Tools, you're prompted to do so. When Core Tools is installed and running, output is shown in the Terminal. This step is the same as running the func start Core Tools command from the Terminal, but with extra build tasks and an attached debugger.

When the project is running, you can use the Execute Function Now... feature of the extension to trigger your functions as you would when the project is deployed to Azure. With the project running in debug mode, breakpoints are hit in Visual Studio Code as you would expect.

  1. In the command pallet, enter Azure Functions: Execute function now and choose Local project.

  2. Choose the function you want to run in your project and type the message body of the request in Enter request body. Press Enter to send this request message to your function. The default text in Enter request body should indicate the format of the body. If your function app has no functions, a notification error is shown with this error.

  3. When the function runs locally and after the response is received, a notification is raised in Visual Studio Code. Information about the function execution is shown in Terminal panel.

Running functions locally doesn't require using keys.

Local settings

When running in a function app in Azure, settings required by your functions are stored securely in app settings. During local development, these settings are instead added to the Values object in the local.settings.json file. The local.settings.json file also stores settings used by local development tools.

Because the local.settings.json may contain secrets, such as connection strings, you should never store it in a remote repository. To learn more about local settings, see Local settings file.

By default, these settings aren't migrated automatically when the project is published to Azure. After publishing finishes, you're given the option of publishing settings from local.settings.json to your function app in Azure. To learn more, see Publish application settings.

Values in ConnectionStrings are never published.

The function application settings values can also be read in your code as environment variables. For more information, see the Environment variables sections of these language-specific reference articles:

Application settings in Azure

The settings in the local.settings.json file in your project should be the same as the application settings in the function app in Azure. Any settings you add to local.settings.json you must also add to the function app in Azure. These settings aren't uploaded automatically when you publish the project. Likewise, any settings that you create in your function app in the portal must be downloaded to your local project.

Publish application settings

The easiest way to publish the required settings to your function app in Azure is to use the Upload settings link that appears after you publish your project:

Screenshot to upload application settings.

You can also publish settings by using the Azure Functions: Upload Local Setting command in the command palette. You can add individual settings to application settings in Azure by using the Azure Functions: Add New Setting command.

Tip

Be sure to save your local.settings.json file before you publish it.

If the local file is encrypted, it's decrypted, published, and encrypted again. If there are settings that have conflicting values in the two locations, you're prompted to choose how to proceed.

View existing app settings in the Azure: Functions area by expanding your subscription, your function app, and Application Settings.

 Screenshot for viewing function app settings in Visual Studio Code.

Download settings from Azure

If you've created application settings in Azure, you can download them into your local.settings.json file by using the Azure Functions: Download Remote Settings command.

As with uploading, if the local file is encrypted, it's decrypted, updated, and encrypted again. If there are settings that have conflicting values in the two locations, you're prompted to choose how to proceed.

Monitoring functions

When you run functions locally, log data is streamed to the Terminal console. You can also get log data when your Functions project is running in a function app in Azure. You can connect to streaming logs in Azure to see near-real-time log data. You should enable Application Insights for a more complete understanding of how your function app is behaving.

Streaming logs

When you're developing an application, it's often useful to see logging information in near-real time. You can view a stream of log files being generated by your functions. This output is an example of streaming logs for a request to an HTTP-triggered function:

Screenshot for streaming logs output for H T T P trigger.

To learn more, see Streaming logs.

To turn on the streaming logs for your function app in Azure:

  1. Select F1 to open the command palette, and then search for and run the command Azure Functions: Start Streaming Logs.

  2. Select your function app in Azure, and then select Yes to enable application logging for the function app.

  3. Trigger your functions in Azure. Notice that log data is displayed in the Output window in Visual Studio Code.

  4. When you're done, remember to run the command Azure Functions: Stop Streaming Logs to disable logging for the function app.

Note

Streaming logs support only a single instance of the Functions host. When your function is scaled to multiple instances, data from other instances isn't shown in the log stream. Live Metrics Stream in Application Insights does support multiple instances. While also in near-real time, streaming analytics is based on sampled data.

Application Insights

We recommend that you monitor the execution of your functions by integrating your function app with Application Insights. When you create a function app in the Azure portal, this integration occurs by default. When you create your function app during Visual Studio publishing, you need to integrate Application Insights yourself. To learn how, see Enable Application Insights integration.

To learn more about monitoring using Application Insights, see Monitor Azure Functions.

C# script projects

By default, all C# projects are created as C# compiled class library projects. If you prefer to work with C# script projects instead, you must select C# script as the default language in the Azure Functions extension settings:

  1. Select File > Preferences > Settings.

  2. Go to User Settings > Extensions > Azure Functions.

  3. Select C#Script from Azure Function: Project Language.

After you complete these steps, calls made to the underlying Core Tools include the --csx option, which generates and publishes C# script (.csx) project files. When you have this default language specified, all projects that you create default to C# script projects. You're not prompted to choose a project language when a default is set. To create projects in other languages, you must change this setting or remove it from the user settings.json file. After you remove this setting, you're again prompted to choose your language when you create a project.

Command palette reference

The Azure Functions extension provides a useful graphical interface in the area for interacting with your function apps in Azure. The same functionality is also available as commands in the command palette (F1). These Azure Functions commands are available:

Azure Functions command Description
Add New Settings Creates a new application setting in Azure. To learn more, see Publish application settings. You might also need to download this setting to your local settings.
Configure Deployment Source Connects your function app in Azure to a local Git repository. To learn more, see Continuous deployment for Azure Functions.
Connect to GitHub Repository Connects your function app to a GitHub repository.
Copy Function URL Gets the remote URL of an HTTP-triggered function that's running in Azure. To learn more, see Get the URL of the deployed function.
Create function app in Azure Creates a new function app in your subscription in Azure. To learn more, see the section on how to publish to a new function app in Azure.
Decrypt Settings Decrypts local settings that have been encrypted by Azure Functions: Encrypt Settings.
Delete Function App Removes a function app from your subscription in Azure. When there are no other apps in the App Service plan, you're given the option to delete that too. Other resources, like storage accounts and resource groups, aren't deleted. To remove all resources, you should instead delete the resource group. Your local project isn't affected.
Delete Function Removes an existing function from a function app in Azure. Because this deletion doesn't affect your local project, instead consider removing the function locally and then republishing your project.
Delete Proxy Removes an Azure Functions proxy from your function app in Azure. To learn more about proxies, see Work with Azure Functions Proxies.
Delete Setting Deletes a function app setting in Azure. This deletion doesn't affect settings in your local.settings.json file.
Disconnect from Repo Removes the continuous deployment connection between a function app in Azure and a source control repository.
Download Remote Settings Downloads settings from the chosen function app in Azure into your local.settings.json file. If the local file is encrypted, it's decrypted, updated, and encrypted again. If there are settings that have conflicting values in the two locations, you're prompted to choose how to proceed. Be sure to save changes to your local.settings.json file before you run this command.
Edit settings Changes the value of an existing function app setting in Azure. This command doesn't affect settings in your local.settings.json file.
Encrypt settings Encrypts individual items in the Values array in the local settings. In this file, IsEncrypted is also set to true, which specifies that the local runtime will decrypt settings before using them. Encrypt local settings to reduce the risk of leaking valuable information. In Azure, application settings are always stored encrypted.
Execute Function Now Manually starts a function using admin APIs. This command is used for testing, both locally during debugging and against functions running in Azure. When a function in Azure starts, the extension first automatically obtains an admin key, which it uses to call the remote admin APIs that start functions in Azure. The body of the message sent to the API depends on the type of trigger. Timer triggers don't require you to pass any data.
Initialize Project for Use with VS Code Adds the required Visual Studio Code project files to an existing Functions project. Use this command to work with a project that you created by using Core Tools.
Install or Update Azure Functions Core Tools Installs or updates Azure Functions Core Tools, which is used to run functions locally.
Redeploy Lets you redeploy project files from a connected Git repository to a specific deployment in Azure. To republish local updates from Visual Studio Code, republish your project.
Rename Settings Changes the key name of an existing function app setting in Azure. This command doesn't affect settings in your local.settings.json file. After you rename settings in Azure, you should download those changes to the local project.
Restart Restarts the function app in Azure. Deploying updates also restarts the function app.
Set AzureWebJobsStorage Sets the value of the AzureWebJobsStorage application setting. This setting is required by Azure Functions. It's set when a function app is created in Azure.
Start Starts a stopped function app in Azure.
Start Streaming Logs Starts the streaming logs for the function app in Azure. Use streaming logs during remote troubleshooting in Azure if you need to see logging information in near-real time. To learn more, see Streaming logs.
Stop Stops a function app that's running in Azure.
Stop Streaming Logs Stops the streaming logs for the function app in Azure.
Toggle as Slot Setting When enabled, ensures that an application setting persists for a given deployment slot.
Uninstall Azure Functions Core Tools Removes Azure Functions Core Tools, which is required by the extension.
Upload Local Settings Uploads settings from your local.settings.json file to the chosen function app in Azure. If the local file is encrypted, it's decrypted, uploaded, and encrypted again. If there are settings that have conflicting values in the two locations, you're prompted to choose how to proceed. Be sure to save changes to your local.settings.json file before you run this command.
View Commit in GitHub Shows you the latest commit in a specific deployment when your function app is connected to a repository.
View Deployment Logs Shows you the logs for a specific deployment to the function app in Azure.

Next steps

To learn more about Azure Functions Core Tools, see Work with Azure Functions Core Tools.

To learn more about developing functions as .NET class libraries, see Azure Functions C# developer reference. This article also provides links to examples of how to use attributes to declare the various types of bindings supported by Azure Functions.