Azure Functions Core Tools: Develop and test Azure Functions locally (with examples)
Azure Functions Core Tools is a command-line tool that enables developers to develop, test, and deploy Azure Functions locally. It allows you to create and run functions locally, connect them to live Azure services, and deploy the function app to an Azure subscription.
In this article, we will go through eight different use cases of the func command, along with code examples and explanations for each use case.
Create a new functions project
To create a new functions project, you can use the func init command followed by the project name.
func init project
project: The name of the project you want to create.
Motivation: Creating a new functions project is the first step in developing Azure Functions locally. This command initializes a new Functions project with the provided name, creating the necessary files and folder structure.
Example Output: If we execute func init myfunctions, it will create a new folder named myfunctions with the necessary files and folders for a Functions project.
Create a new function
Once you have a functions project, you can create a new function using the func new command.
func new
Motivation: Creating a new function allows you to define the trigger and bindings for your function. This command generates a new function template with the necessary files and code structure.
Example Output: Executing func new will prompt you to select a function template from a list. Once selected, it will create the necessary files and code structure for that specific function.
Run functions locally
To run your functions locally, you can use the func start command.
func start
Motivation: Running functions locally allows you to test and debug them before deploying to Azure. This command starts a local runtime environment that simulates the Azure Functions platform, allowing you to execute and interact with your functions.
Example Output: Executing func start will start the local runtime and display logs indicating the status of the runtime environment. It will also provide the local URL where you can access your functions.
Publish your code to a function app in Azure
To publish your code to an Azure function app, you can use the func azure functionapp publish command followed by the function app name.
func azure functionapp publish function_app
function_app: The name of the Azure function app you want to publish to.
Motivation: Publishing your code to an Azure function app deploys your functions to the cloud, making them accessible over the internet. This command packages your code and dependencies and deploys them to the specified function app in Azure.
Example Output: If we execute func azure functionapp publish myfunctionapp, it will deploy the code from the local functions project to the Azure function app named myfunctionapp.
Download all settings from an existing function app
To download all settings from an existing function app, you can use the func azure functionapp fetch-app-settings command followed by the function app name.
func azure functionapp fetch-app-settings function_app
function_app: The name of the Azure function app you want to fetch settings from.
Motivation: Settings in an Azure function app, such as connection strings and application settings, are often stored separately from the code. This command allows you to download all the settings from an existing function app, which can be useful for local development or backup purposes.
Example Output: If we execute func azure functionapp fetch-app-settings myfunctionapp, it will download all the settings from the Azure function app named myfunctionapp and save them locally in a JSON file.
Get the connection string for a specific storage account
To get the connection string for a specific storage account associated with your function app, you can use the func azure storage fetch-connection-string command followed by the storage account name.
func azure storage fetch-connection-string storage_account
storage_account: The name of the storage account you want to fetch the connection string for.
Motivation: Azure Functions often utilize Azure Storage for various purposes, such as storing logs or input/output bindings. This command allows you to retrieve the connection string for a specific storage account, which is required to interact with that storage account from your functions.
Example Output: If we execute func azure storage fetch-connection-string mystorageaccount, it will retrieve the connection string for the storage account named mystorageaccount.
