| title | description | ms.topic | ms.custom | ms.date |
|---|---|---|---|---|
Develop Azure Functions by using Visual Studio Code |
Learn how to develop and test Azure Functions by using the Azure Functions extension for Visual Studio Code. |
conceptual |
devx-track-csharp |
02/21/2021 |
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.
Before you install and run the Azure Functions extension, you must meet these requirements:
-
Visual Studio Code installed on one of the supported platforms.
-
An active Azure subscription.
[!INCLUDE quickstarts-free-trial-note]
Other resources that you need, like an Azure storage account, are created in your subscription when you publish by using Visual Studio Code.
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.
-
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.
-
Java 8 recommended. For other supported versions, see Java versions.
-
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.
-
Node.js, Active LTS and Maintenance LTS versions (10.14.1 recommended). Use the
node --versioncommand to check your version.
-
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.
-
PowerShell 7 recommended. For version information, see PowerShell versions.
-
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.
-
Python 3.x. For version information, see Python versions by the Azure Functions runtime.
-
Python extension for Visual Studio Code.
[!INCLUDE functions-install-vs-code-extension]
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.
-
From Azure: Functions, select the Create Function icon:
-
Select the folder for your function app project, and then Select a language for your function project.
-
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.
-
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.
A function is created in your chosen language and in the template for an HTTP-triggered function.
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:
- HttpExample.cs class library file that implements the function.
-
A pom.xml file in the root folder that defines the project and deployment parameters, including project dependencies and the Java version. The pom.xml also contains information about the Azure resources that are created during a deployment.
-
A Functions.java file in your src path that implements the function.
-
A package.json file in the root folder.
-
An HttpExample folder that contains the function.json definition file and the index.js file, a Node.js file that contains the function code.
- An HttpExample folder that contains the function.json definition file and the run.ps1 file, which contains the function code.
-
A project-level requirements.txt file that lists packages required by Functions.
-
An HttpExample folder that contains the function.json definition file and the __init__.py file, which contains the function code.
At this point, you can add input and output bindings to your function. You can also add a new function to your project.
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 command installs the Azure Storage extension, which implements bindings for Blob, Queue, and Table storage.
dotnet add package Microsoft.Azure.WebJobs.Extensions.Storage --version 3.0.4[!INCLUDE functions-extension-bundles]
[!INCLUDE functions-extension-bundles]
[!INCLUDE functions-extension-bundles]
[!INCLUDE functions-extension-bundles]
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.
A new Java (.java) file is added to your project.
A new folder is created in the project. The folder contains a new function.json file and the new JavaScript code file.
A new folder is created in the project. The folder contains a new function.json file and the new PowerShell code file.
A new folder is created in the project. The folder contains a new function.json file and the new Python code file.
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:
:::code language="csharp" source="~/functions-docs-csharp/functions-add-output-binding-storage-queue-cli/HttpExample.cs" range="17":::
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:
:::code language="csharp" source="~/functions-docs-csharp/functions-add-output-binding-storage-queue-cli/HttpExample.cs" range="30-31":::
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.
Update the function method to add the following parameter to the Run method definition:
:::code language="java" source="~/functions-quickstart-java/functions-add-output-binding-storage-queue/src/main/java/com/function/Function.java" range="20-21":::
The msg parameter is an OutputBinding<T> type, where is T is a string that is written to an output binding when the function completes. The following code sets the message in the output binding:
:::code language="java" source="~/functions-quickstart-java/functions-add-output-binding-storage-queue/src/main/java/com/function/Function.java" range="33-34":::
This message is 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.
[!INCLUDE functions-add-output-binding-vs-code]
In your function code, the msg binding is accessed from the context, as in this example:
:::code language="javascript" range="5-7" source="~/functions-docs-javascript/functions-add-output-binding-storage-queue-cli/HttpExample/index.js":::
This message is 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.
[!INCLUDE functions-add-output-binding-vs-code]
:::code language="powershell" range="18-19" source="~/functions-docs-powershell/functions-add-output-binding-storage-queue-cli/HttpExample/run.ps1":::
This message is 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.
[!INCLUDE functions-add-output-binding-vs-code]
Update the Main definition to add an output parameter msg: func.Out[func.QueueMessage] so that the definition looks like the following example:
:::code language="python" range="6" source="~/functions-docs-python/functions-add-output-binding-storage-queue-cli/HttpExample/init.py":::
The following code adds string data from the request to the output queue:
:::code language="python" range="18" source="~/functions-docs-python/functions-add-output-binding-storage-queue-cli/HttpExample/init.py":::
This message is 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.
[!INCLUDE functions-sign-in-vs-code]
Visual Studio Code lets you publish your Functions project directly to Azure. In the process, you create a function app and related resources in your Azure subscription. The function app provides an execution context for your functions. The project is packaged and deployed to the new function app in your Azure subscription.
When you publish from Visual Studio Code to a new function app in Azure, you can choose either a quick function app create path using defaults or an advanced path, where you have more control over the remote resources created.
When you publish from Visual Studio Code, you take advantage of the Zip deploy technology.
When you choose + Create new function app in Azure..., the extension automatically generates values for the Azure resources needed by your function app. These values are based on the function app name that you choose. For an example of using defaults to publish your project to a new function app in Azure, see the Visual Studio Code quickstart article.
If you want to provide explicit names for the created resources, you must choose the advanced create path.
The following steps publish your project to a new function app created with advanced create options:
-
In the command pallet, enter Azure Functions: Deploy to function app.
-
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.
-
If you have multiple subscriptions, Select a subscription for the function app, and then select + Create New Function App in Azure... Advanced. This Advanced option gives you more control over the resources you create in Azure.
-
Following the prompts, provide this information:
Prompt Value Description Select function app in Azure Create New Function App in Azure At the next prompt, 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 an OS Windows The function app runs on Windows. Select a hosting plan Consumption plan A serverless Consumption plan hosting is used. Select a runtime for your new app Your project language The runtime must match the project that you're publishing. Select a resource group for new resources Create New Resource Group At the next prompt, type a resource group name, like myResourceGroup, and then select enter. You can also select an existing resource group.Select a storage account Create new storage account At the next 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 a location for new resources region Select a location in a region near you or near other services that your functions access. 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.
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.
-
Select F1 to open the command palette, and then search for and run the command Azure Functions: Copy Function URL.
-
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 getting the URL of functions in Azure, 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.
When you set up continuous deployment, your function app in Azure is updated when you update source files in the connected source location. We recommend continuous deployment, but you can also republish your project file updates from Visual Studio Code.
Important
Publishing to an existing function app overwrites the content of that app in Azure.
[!INCLUDE functions-republish-vscode]
The Azure Functions extension lets you run individual 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.
To execute a function in Azure from Visual Studio Code.
-
In the command pallet, enter Azure Functions: Execute function now and choose your Azure subscription.
-
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.
-
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.
-
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 running functions in Azure, 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.
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 additional requirements.
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:
-
In Visual Studio, open Cloud Explorer, expand Storage Account > Your Storage Account, and then select Properties and copy the Primary Connection String value.
-
In your project, open the local.settings.json file and set the value of the AzureWebJobsStorage key to the connection string you copied.
-
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.
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 is the same as running the func host 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.
-
In the command pallet, enter Azure Functions: Execute function now and choose Local project.
-
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.
-
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.
[!INCLUDE functions-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:
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.
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:
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.
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.
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 either connect to streaming logs in Azure to see near-real-time log data, or you can enable Application Insights for a more complete understanding of how your function app is behaving.
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:
To learn more, see Streaming logs.
[!INCLUDE functions-enable-log-stream-vs-code]
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.
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.
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:
-
Select File > Preferences > Settings.
-
Go to User Settings > Extensions > Azure Functions.
-
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.
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 triggering a function in Azure, 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. |
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.