- \n
- Visual Studio 2017<\/a> (v15.5 or above) with Azure development workload<\/a><\/li>\n
- Access to a Slack<\/a> workspace<\/li>\n<\/ul>\n
Create a Function App (Timer Trigger)<\/h4>\n
We all know how important it is to take regular breaks if you spend all day sitting at a desk, right? So, in this tutorial, we’ll use a Timer Trigger function to post a message to a Slack channel at regular intervals to remind you (and your whole team) to take a break. A Timer Trigger is a type of Azure Function that is triggered to run on regular time intervals.<\/p>\n
Just run it<\/h5>\n
If you want to skip ahead and run the function locally, fetch the source from this repo<\/a>, insert the appropriate Slack channel(s) and OAuth token in the local.settings.json file, start the Azure Storage Emulator, then Run (or Debug) the Functions app in Visual Studio.<\/p>\n
Step-by-step guide<\/h5>\n
- \n
- Open Visual Studio 2017 and select File->New Project<\/strong>.<\/li>\n
- Select Azure Functions<\/strong> under the Visual C# category.<\/li>\n
- Provide a name (e.g. TakeABreakFunctionApp) and press OK<\/strong>.\n The New Function Project dialog will open.<\/li>\n
- Select Azure Functions v1 (.NET Framework)<\/strong>, chose Timer trigger<\/strong> and press OK<\/strong>.\n Note: This will also work with Azure Functions v2, but for this tutorial I\u2019ve chosen v1, since v2 is still in preview.
<\/p>\n![\"New](\"https:\/\/devblogs.microsoft.com\/aspnet\/wp-content\/uploads\/sites\/16\/2017\/12\/NewTimerTrigger-1.png\")
<\/a><\/p>\nA new solution is created with a Functions App project and single class called Function1 that contains a basic Timer trigger.<\/li>\n
- Edit Function1.cs.\n
- \n
- Add helper methods:\n
- \n
- Env (for fetching environment variables)<\/li>\n
- SendHttpRequest (for sending authenticated http requests)<\/li>\n
- SendMessageToSlack (for generating and sending the appropriate Slack request – based on environment variables)<\/li>\n<\/ul>\n<\/li>\n
- Update method: Run<\/strong>\n
- \n
- Change the return type to async Task<\/b><\/i>.<\/li>\n
- Add an asynchronous call to the SendMessageToSlack<\/strong> method.<\/li>\n
- Update Chron settings for the TimerTrigger<\/strong> attribute.<\/li>\n<\/ul>\n<\/li>\n
- Add appropriate Using<\/strong> statements.<\/li>\n<\/ul>\n<\/li>\n
The completed code should look like this:<\/p>\nusing System;\nusing System.Net.Http;\nusing System.Net.Http.Headers;\nusing System.Threading.Tasks;\nusing Microsoft.Azure.WebJobs;\nusing Microsoft.Azure.WebJobs.Host;\n \nnamespace TakeABreakFunctionsApp\n{\n public static class Function1\n {\n [FunctionName(\"Function1\")]\n public static async Task Run([TimerTrigger(\"0 *\/30 * * * *\")]TimerInfo myTimer, TraceWriter log)\n {\n log.Info($\"C# Timer trigger function executed at: {DateTime.Now}\");\n await SendMessageToSlack(\"You're working too hard. How about you take a break?\", log);\n }\n \n private static async Task SendMessageToSlack(string message, TraceWriter log)\n {\n \/\/ Fetch environment variables (from local.settings.json when run locally)\n string channel = Env(\"ChannelToNotify\");\n string slackbotUrl = Env(\"SlackbotUrl\");\n string bearerToken = Env(\"SlackOAuthToken\");\n \n \/\/ Prepare request and send via Http\n log.Info($\"Sending to {channel}: {message}\");\n string requestUrl = $\"{slackbotUrl}?channel={Uri.EscapeDataString(channel)}&text={Uri.EscapeDataString(message)}\";\n await SendHttpRequest(requestUrl, bearerToken);\n }\n\n private static async Task SendHttpRequest(string requestUrl, string bearerToken)\n {\n HttpClient httpClient = new HttpClient();\n httpClient.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue(\"Bearer\", bearerToken);\n HttpResponseMessage response = await httpClient.GetAsync(requestUrl);\n }\n\n private static string Env(string name) => Environment.GetEnvironmentVariable(name, EnvironmentVariableTarget.Process);\n }\n}<\/span><\/code><\/pre>\n- Edit local.settings.json.\nAdd the following environment variables.<\/p>\n
- \n
- SlackbotUrl – The URL for the Slack API to post chat messages<\/li>\n
- SlackOAuthToken – An OAuth token that grants permission for your app to send messages to a Slack workspace.\n – See below for help generating a Slack OAuth token.<\/li>\n
- ChannelToNotify – The Slack channel to send messages to<\/li>\n<\/ul>\n<\/li>\n
Your local.settings.json should look something like this:\n(Your SlackOAuthToken and ChannelToNotify variables will be specific to your Slack workspace.)<\/p>\n
{\n \"IsEncrypted\": false,\n \"Values\": {\n \"AzureWebJobsStorage\": \"UseDevelopmentStorage=true\",\n \"AzureWebJobsDashboard\": \"UseDevelopmentStorage=true\",\n \"SlackbotUrl\": \"https:\/\/slack.com\/api\/chat.postMessage\",\n \"SlackOAuthToken\": \"[insert your generated token]\",\n \"ChannelToNotify\": \"[your channel id]\"\n }\n}<\/span><\/code><\/pre>\n<\/ol>\nYour Functions app is now ready to run! You just need to grab an authorization token for your Slack workspace.<\/p>\n
Generate an OAuth token for your app to send messages to your Slack workspace<\/h4>\n
Before you can post a message to a Slack workspace, you must first tell Slack about the app and assign specific permissions for the app to send messages as a bot. Once you’ve installed the app to the Slack workspace, you will be issued an OAuth token that you can send with your http requests. For full details, you can follow the instructions here<\/a>. Otherwise, follow the steps below.<\/p>\n
- \n
- \nClick here<\/a> to register your new Functions app with your Slack workspace.<\/li>\n
- Provide a name (e.g. “Take a Break”) and select the appropriate Slack workspace, then press Create App<\/strong>.<\/li>\n
![\"Create](\"https:\/\/devblogs.microsoft.com\/aspnet\/wp-content\/uploads\/sites\/16\/2017\/12\/CreateASlackApp-1-1.png\")
<\/a><\/p>\nWhen the app is registered with Slack, the Slack API management page opens for the new app.<\/p>\n
- Select OAuth & Permissions<\/strong> from the navigation menu on the left.<\/li>\n
- In the OAuth & Permissions page, scroll down to Scopes<\/strong>, select the permission chat:write:bot<\/strong>, then select Save Changes<\/strong>.<\/li>\n
![\"Select](\"https:\/\/devblogs.microsoft.com\/aspnet\/wp-content\/uploads\/sites\/16\/2017\/12\/SelectPermissionScopes-2.png\")
<\/a><\/p>\n- After the scope permissions have been created and the page has refreshed, scroll to the top of the OAuth & Permissions page and select Install App to Workspace<\/strong>.<\/li>\n
![\"Slack](\"https:\/\/devblogs.microsoft.com\/aspnet\/wp-content\/uploads\/sites\/16\/2017\/12\/SlackInstallAppToWorkspace-1-1.png\")
<\/a><\/p>\n- A confirm page opens. Review the details, then click Authorize<\/strong>.<\/li>\n
- Your OAuth Access Token is generated and presented at the top of the page.<\/li>\n
![\"OAuth](\"https:\/\/devblogs.microsoft.com\/aspnet\/wp-content\/uploads\/sites\/16\/2017\/12\/OAuthAccessToken-1.png\")
<\/a><\/p>\n- Copy this token and add it to your local.settings.json as the value for SlackOAuthToken<\/strong>.
\nNote<\/strong>: The OAuth access token is a secret and should not be made public. If you check this token into a public source control system like GitHub, Slack will find it and permanently disable it!<\/li>\n<\/ul>\nRun your Functions App on your local machine<\/h4>\n
Now that you\u2019ve registered your app with Slack and have provided a valid OAuth token in your local.settings.json, you can run the Function locally.<\/p>\n
Start the local Storage Emulator<\/h5>\n
You can configure your function to use a storage account on Azure. But if your app is configured to use development storage (which is the default for new Functions), then it will run against the local Azure Storage Emulator. Therefore, you\u2019ll need to make sure the Storage Emulator is started before running your Functions app.<\/p>\n
- \n
- Open the Windows Start Menu and search for “Storage Emulator”.<\/li>\n<\/ul>\n
Microsoft Azure Storage Emulator will launch. You can manage it via the icon in the Windows System Tray.<\/p>\n
Start the Function app from Visual Studio<\/h5>\n
- \n
- Press Ctrl+F5 to build and run the Functions app.<\/li>\n
- If prompted, update to the latest Functions tools.<\/li>\n
- A new command window launches and displays the log output from the Functions app.<\/li>\n<\/ul>\n
![\"Function](\"https:\/\/devblogs.microsoft.com\/aspnet\/wp-content\/uploads\/sites\/16\/2017\/12\/FunctionAppRunning-1.png\")
<\/a><\/p>\nAfter a certain period of time, the Timer trigger will fire and send a message to your Slack workspace.<\/p>\n
![\"Function](\"https:\/\/devblogs.microsoft.com\/aspnet\/wp-content\/uploads\/sites\/16\/2017\/12\/FunctionTimerExecutes-1.png\")
<\/a><\/p>\nYou should see the message appear in the appropriate Slack channel.<\/p>\n
![\"Message](\"https:\/\/devblogs.microsoft.com\/aspnet\/wp-content\/uploads\/sites\/16\/2017\/12\/MessageAppearsInSlack-1.png\")
<\/a><\/p>\nFeel free to play around with the Timer Chron options in the Run method’s attributes to configure the function to execute at the intervals you’d like. Here are some example Chron settings.\n Trigger Chron format: (seconds minutes hours days months years)\n (“0 *\/15 6-20 * * *”) = Every 15 minutes, between 06:00 AM and 08:59 PM\n (“0 0 0-5,21-23 * * *”) = Every hour from 12:00 AM to 06:00 AM and 09:00 PM to 12:00 AM<\/p>\n
Congratulations!<\/strong> You’ve written a working Azure Functions App with a Timer trigger function.<\/p>\n
What’s next?<\/h5>\n
Publish your Functions App to the cloud<\/b>\nSo that your Functions app is always available, and can be accessed globally (eg. For Http trigger types), you can publish your app to the cloud. This article<\/a> describes the process of publishing a Functions app to Azure.<\/p>\nExperiment with other Functions types<\/b>\nThere’s an excellent collection of open-source samples available here<\/a>. Poke around and see what takes your interest.<\/p>\n
- Provide a name (e.g. “Take a Break”) and select the appropriate Slack workspace, then press Create App<\/strong>.<\/li>\n
- \nClick here<\/a> to register your new Functions app with your Slack workspace.<\/li>\n
- Add an asynchronous call to the SendMessageToSlack<\/strong> method.<\/li>\n
- Change the return type to async Task<\/b><\/i>.<\/li>\n
- Select Azure Functions<\/strong> under the Visual C# category.<\/li>\n
- Access to a Slack<\/a> workspace<\/li>\n<\/ul>\n