# Azure Functions Backend

Simple plugin that proxies requests to the Azure Portal API through Azure SDK JavaScript libraries.

*Inspired by [roadie.io AWS Lamda plugin](https://roadie.io/backstage/plugins/aws-lambda/)*

## Setup

The following sections will help you get the Azure Functions Backend plugin setup and running.

### Configuration

The Azure Functions plugin requires the following YAML to be added to your app-config.yaml:

```yaml
azureFunctions:
  domain:
  tenantId:
  clientId:
  clientSecret:
  allowedSubscriptions:
    - id:
      name:
```

Configuration Details:

- `domain` can be found by visiting the [Directories + Subscriptions settings page](https://portal.azure.com/#settings/directory). Alternatively you can inspect the [Azure home](https://portal.azure.com/#home) URL - `https://portal.azure.com/#@<Your_Domain>/`.
- `tenantId` can be found by visiting [Azure Directory Overview page](https://portal.azure.com/#blade/Microsoft_AAD_IAM/ActiveDirectoryMenuBlade).
- `clientId` and `clientSecret` can be the same values you used for [Azure DevOps Backend](https://github.com/backstage/backstage/tree/master/plugins/azure-devops-backend) or [Azure Integration](https://backstage.io/docs/integrations/azure/org#app-registration) as long as this App Registration has permissions to read your function apps.
- `allowedSubscriptions` is an array of `id` and `name` that will be used to iterate over and look for the specified functions' app. `id` and `name` can be found the [Subscriptions page](https://portal.azure.com/#view/Microsoft_Azure_Billing/SubscriptionsBlade).

### Integrating

Here's how to get the backend plugin up and running:

1. First we need to add the `@backstage/plugin-azure-functions-backend` package to your backend:

    ```sh
    # From the Backstage root directory
    cd packages/backend
    yarn add @backstage/plugin-azure-functions-backend
    ```

2. Then we will create a new file named `packages/backend/src/plugins/azure-functions.ts`, and add the following to it:

    ```ts
    import { createRouter, AzureWebManagementApi } from '@backstage/plugin-azure-functions-backend';
    import { Router } from 'express';
    import { PluginEnvironment } from '../types';

    export default async function createPlugin(
      env: PluginEnvironment,
    ): Promise<Router> {
      return await createRouter({
        logger: env.logger,
        azureWebManagementApi: AzureWebManagementApi.fromConfig(env.config)
      });
    }
    ```

3. Next we wire this into the overall backend router, edit `packages/backend/src/index.ts`:

    ```ts
    import azureFunctions from './plugins/azure-functions';

    // Removed for clairty...

    async function main() { 
      // ...
      // Add this line under the other lines that follow the useHotMemoize pattern
      const azureFunctionsEnv = useHotMemoize(module, () => createEnv('azureFunctions'));
      
      // ...
      // Insert this line under the other lines that add their routers to apiRouter in the same way
      apiRouter.use('/azure-functions', await azureFunctions(azureFunctionsEnv));
    }
    ```

4. Now run `yarn start-backend` from the repo root.

5. Finally, open `http://localhost:7007/api/azure-functions/health` in a browser, it should return `{"status":"ok"}`.