Azure Functions Core Tools:

This is a continuation of a series of articles on Azure services from an operational engineering perspective with the most recent introduction to Azure App Configuration with the link here. This article discusses Azure Functions Core Tools.

 

Azure Functions Core Tools help to develop and test Azure Functions on the local computer from the command prompt or terminal.  The local function can connect to live Azure Services, and this helps to debug functions on the local computer using the full Functions runtime. It can even help deploy a function application to the Azure subscription. The basic steps are as follows:

1.       Install the core tools and dependencies – The prerequisites for these are Azure CLI or Azure PowerShell.  The core tools version depends on Azure Functions. The version used depends on the local development environment, choice of language and the level of support required.

A version of the same runtime that powers Azure Function can also be run on the local computer.

2.       Create a local functions project: The project directory contains the following files and folders, regardless of language: host.json, local.settings.json, .gitignore, and .vscode\extensions.json. The command “func init [projectFileName]” can create the necessary structure and boilerplate scaffolding.

3.       Register extensions: Function triggers and bindings are implemented as .Net extensions (NuGet) package. These can be referred for the specific triggers and bindings. HTTP bindings and timer triggers don’t require extensions.

4.       Use Extension bundles.  Binding extensions can be installed by enabling extension bundles. When we enable bundles, a predefined set of extension packages is automatically installed. The host.json file bears the additional entry comprising of a version and extensionBundle to enable it.

5.       Install extensions one by one – If there is a non-.Net project, extension bundles cannot be used. Then we need to target a specific version of an extension not in the bundle. In these cases, Core Tools can be used to install the extensions one by one locally.

6.       Local Settings: Settings required by functions are stored securely in app settings when the function is run. When the functions are local, the settings are added to the Values object in the local.settings.json file. The local.settings.json file also stores settings used by the local development tools.

7.       Get the storage connections strings: With the help of the Microsoft Azure Storage Emulator for development, it is possible to run the function locally with an actual storage connection string.

8.       Create the function: The creation of a function in an existing project is done with the help of the “func new” command.

9.       Run the functions locally with the help of the func start command.

 

With these steps, we can get started with an application function in the local development environment and test data can be passed to it.