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Introduction to the Looker extension framework

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The Looker extension framework will soon use a new loading mechanism. The new loader may cause errors when existing extensions are loaded. For instructions on how to test your extensions with the new loader before it is officially turned on in Looker environments, see the Testing the new extension framework loader article in the Looker Help Center.

The Looker extension framework is a development framework that significantly reduces the effort and complexity of building custom JavaScript data applications and tools, such as:

  • Internal platform applications for your company
  • External platforms for your customers, such as customer portals for Embedded Analytics applications built with data in Looker
  • Targeted internal tools
  • Applications for embedding in external applications

Current examples of Looker extensions that are available on the Looker Marketplace include the Looker Data Dictionary and the LookML Diagram.

Why use the extension framework?

Some parts of building web applications are easy and fun, while others are obviously more time-consuming and not exactly fun. The extension framework helps you by streamlining many of these not-so-fun tasks.

The extension framework takes care of some of the more tedious aspects of building a web application so that you can focus on starting development right away. Custom applications and tools created with the extension framework can be accessed from within Looker, allowing Looker to handle the following kinds of functions, such as:

Extension framework features

The Looker extension framework includes the following features:

  • The Looker Extension SDK, which provides functions for Looker public API access and for interacting within the Looker environment.
  • Looker components, a library of pre-built React UI components you can use in your extensions.
  • The Embed SDK, a library you can use to embed dashboards, Looks, and Explores in your extension. See the kitchen sink extension for example code. You can also use the Embed SDK to embed your extension into third-party applications. Cookies must be enabled in the browser when you’re embedding Explores, Looks, or dashboards into an extension.
  • The create-looker-extension utility, which creates a basic extension that includes all the necessary extension files and dependencies, and you can use as a starting point to build upon.
  • Our Looker extension framework examples repo, which includes templates and sample extensions to assist you in getting started quickly.
  • The ability to access third-party API endpoints and add third-party data to your extension.

  • The ability to create full-screen extensions within Looker. Full-screen extensions can be used for internal or external platform applications.

    In a full-screen extension, you can prevent a set of users from navigating to other parts of Looker from your extension by adding users to an Extensions Only user group. You can also remove the Looker navigation bar by replacing /extensions with /spartan in the extension URL.

  • The ability to configure an access key for your extension so that users must enter a key to run the extension. This is useful if you want to charge for your extension, but you should use standard Looker permissions to gate access to those who should never be able to access an extension.

Extension framework requirements

To develop using the Looker extension framework:

In order to run inside of Looker, every extension, regardless of its function, must include the following elements inside of Looker:

  • A LookML project that:

  • The LookML model file needs a connection parameter that points to a valid database connection on your instance.

  • The project manifest file requires an application parameter. The application parameter gives the extension a label, tells Looker where to find the extension JavaScript, and provides a list of entitlements for the extension. Entitlements define the Looker resources that the extension can access. The extension will not be able to access a Looker resource unless that resource is listed in the entitlements. The following is an example project manifest file with an application parameter:

    project_name: "super_duper_extension" application: super_duper_extension { label: "Super Duper Extension" url: "http://localhost:8080/dist/bundle.js" entitlements: { local_storage: no navigation: no new_window: no new_window_external_urls: [] use_form_submit: yes use_embeds: no use_downloads: no core_api_methods: [] external_api_urls: [] oauth2_urls: [] scoped_user_attributes: [] global_user_attributes: [] } }

    For details, see the application parameter documentation page.

Getting started developing with the Looker extension framework

The easiest way to get started is to first generate a new starter extension from a template, and then customize and add functionality to that starter. This ensures that all configuration and packaging is correct, which can be difficult to do by hand. See the Introduction to building a Looker extension documentation page for instructions on how to create a new Looker project for your extension and generate a starter extension.

For more customized or advanced templates, you can browse the Looker Extension Framework Examples repository. Any extension in that repository can be cloned and repurposed as a starting point for your project.

Once you have created a simple extension and verified that everything is working, you can begin to add additional functionality and customizations:

  • You can see a list of common use cases with example code on the Looker extension framework code examples documentation page.

  • Reference the Looker UI Components site to use our components library for rapid UI and layout development.

  • The Looker Extension Kitchensink Template is an extension that provides examples of a large variety of extension functionality. You can use this template as an encyclopedia or a reference guide, but not as a starting point or an actual template. We recommend that you use our extension generator or clone one of the more simple examples to begin.