Azure Durable Functions Pattern: Approval Workflow with Slack

00 Feature

Introduction

Recently, I published a post about implementing an Approval Workflow on Azure Durable Functions with SendGrid. In essence, this post is not very different to that one. However, I wanted to demonstrate the same pattern on Azure Durable Functions, but now using Slack as a means of approval. My aim is to show how easy it is to implement this pattern by using a Restful API instead of an Azure Functions binding. What you see here could easily be implemented with your own custom APIs as well :).

Scenario

In my previous post, I show how Furry Models Australia streamlined an approval process for aspiring cats to join the exclusive model agency by implementing a serverless solution on Azure Durable Functions and SendGrid. Now, after a great success, they’ve launched a new campaign targeting rabbits. However, for this campaign they need some customisation. The (rabbit) managers of this campaign have started to collaborate internally with Slack instead of email. Their aim is to significantly improve their current approval process based on phone and pigeon post by having an automated serverless workflow which leverages Slack as their internal messaging platform.

11 Sorry

Pre-requisites

To build this solution, we need:

  • Slack
    • Workspace: In case you don’t have one, you would need to create a workspace on Slack, and you will need permissions to manage apps in the workspace.
    • Channel: On that workspace, you need to create a channel where all approval requests will be sent to.
    • App: Once you have admin privileges on your Slack workspace, you should create a Slack App.
    • Incoming Webhook: On your Slack app, you would need to activate incoming webhooks and then activate a new webhook. The incoming webhook will post messages to the channel you have just created. For that, you must authorise the app to post messages to the channel. Once you have authorised it, you should be able to get the Webhook URL. You will need this URL to configure your Durable Function to post an approval request message every time an application has been received.
    • Message Template: To be able to send interactive button messages to Slack we need to have the appropriate message template.
    • Interactive Components: The webhook configured above enables you to post messages to Slack. Now you need a way to get the response from Slack, for this you can use interactive message buttons. To configure the interactive message button, you must provide a request URL. This request URL will be the URL of the HttpTrigger Azure function that will handle the approval selection.
  • Azure Storage Account: The solution requires a Storage Account with 3 blob containers: requestsapproved, and rejected. The requests container should have public access level so blobs can be viewed without a SAS token. For your own solution, you could make this more secure.

Solution Overview

The figure bellow, shows an overview of the solution we will build based on Durable Functions. As you can see, the workflow is very similar to the one implemented previously. Pictures of the aspiring rabbits are to be dropped in an Azure storage account blob container called requests. At the end of the approval workflow, pictures should be moved to the approved or rejected blob containers accordingly.

20 Solution Overview

The steps of the process are described as follows:

  1. The process is being triggered by an Azure Function with the BlobTrigger input binding monitoring the requests blob container. This function also implements the DurableOrchestrationClient attribute to instantiate a Durable Function orchestration
  2. The DurableOrchestrationClient starts the orchestration.
  3. Then, the Durable Function orchestration calls another function with the ActivityTrigger input binding, which is in charge of sending the approval request to Slack as a Slack interactive message.
  4. The interactive message is posted on Slack. This interactive message includes a callbackId field in which we send the orchestration instance id.
  5. Then, in the orchestration, a timer is created so that the approval workflow does not run forever, and in case no approval is received before a timeout, the request is rejected.
  6. The (rabbit) user receives the interactive message on Slack, and decides whether the aspiring rabbit deserves to join Furry Models, by clicking either the Approve or Reject button. The slack interactive message button will send the response to the configured URL on the Interactive Component of the Slack App (this is the URL of the HttpTrigger function which handles the Slack approval response). The response contains the callbackId field which will allow the correlation in the next step.
  7. The HttpTrigger function receives the response which contains the selection and the callbackId. This function gets the orchestration instance id from the callbackId and checks the status of that instance; if it’s not running, it returns an error message to the user. If it’s running, it raises an event to the corresponding orchestration instance.
  8. The corresponding orchestration instance receives the external event.
  9. The workflow continues when the external event is received or when the timer finishes; whatever happens first. If the timer finishes before a selection is received, the application is automatically rejected.
  10. The orchestration calls another ActivityTrigger function to move the blob to the corresponding container (approved or rejected).
  11. The orchestration finishes.

A sample of the Slack interactive message is shown below.

31 Sample Message

Then, when the user clicks on any of the buttons, it will call the HttpTrigger function described in the step 7 above. Depending on the selection and the status of the orchestration, it will receive the corresponding response:

32 Sample Response

The Solution

The implemented solution code can be found in this GitHub repo. I’ve used the Azure Functions Runtime v2. I will highlight some relevant bits of the code below, and I hope that the code is self-explanatory 😉:

TriggerApprovalByBlob.cs

This BlobTrigger function is triggered when a blob is created in a blob container and starts the Durable Function ochestration (Step 1 above)

 

 

 

 

 

OrchestrateRequestApproval.cs

This is the Durable Function orchestration which handles the workflow and is started by the step 2 above.

 

 

 

 

 

 

SendApprovalRequestViaSlack.cs

ActivityTrigger function which sends the approval request via Slack as an Interactive Message (Step 3 above).

 

 

 

 

ProcessSlackApprovals.cs

HttpTrigger function that handles the response of the interactive messages from Slack (Step 7 above).

 

 

MoveBlob.cs

ActivityTrigger function that moves the blob to the corresponding container (Step 10 above).

 

local.settings.json

These are the settings which configure the behaviour of the solution, including the storage account connection strings, the Slack incoming webhook URL, templates for the interactive message, among others.

You would need to implement these as app settings when deploying to Azure

 

 

 

Wrapping up

In this post, I’ve shown how to implement an Approval Workflow (Human Interaction pattern) on Azure Durable Functions with Slack. On the way, we’ve also seen how to create Slack Apps with interactive messages. What you read here can easily be implemented using your own custom APIs. What we’ve covered should allow you to build serverless approval workflows on Azure with different means of approval. I hope you’ve found the posts of this series useful.

Happy clouding!

Cross-posted on Deloitte Platform Engineering Blog
Follow me on @pacodelacruz

Advertisements

Azure Durable Functions Pattern: Approval Workflow with SendGrid

Introduction

Durable Functions is a new (in preview at the time of writing) and very interesting extension of Azure Functions that allows you to build stateful and serverless code-based workflows. The Durable Functions extension abstracts all the state management, queueing, and checkpoint implementation commonly required for an orchestration engine. Thus, you just need to focus on your business logic without worrying much on the underlying complexities. Thanks to this extension, now you can:

  1. Implement long-running serverless code-based services beyond the current Azure Function limitation of 10 minutes (as long as you can break down your process into small nano-services which can be orchestrated);
  2. Chain Azure functions, i.e., call one function after the other and pass the output of the first one as an input to the next one (Function chaining pattern);
  3. Execute several functions asynchronously and then continue the workflow when any or all of the asynchronous tasks are completed (Fan-out and Fan-in pattern);
  4. Get the status of a long-running workflow from external clients (Async HTTP APIs Pattern);
  5. Implement the correlation identifier pattern to enable human interaction processes, such as an approval workflow (Human Interaction Pattern) and;
  6. Implement a flexible recurring process with lifetime management (Monitoring Pattern).

It’s worth noting that Azure Durable Functions is not the only way to implement stateful workflows in a serverless manner on Azure. Azure Logic Apps is another awesome platform, core component of the Microsoft Azure iPaaS, that allows you to build serverless and stateful workflows using a designer. In a previous post, I showed how to implement the approval workflow pattern on Logic Apps via SMS messages leveraging Twilio.

In this post, I will show how to implement the Human Interaction Pattern on Azure Durable Functions with SendGrid. You will see on the way that this implementation requires other Durable Functions patterns, such as, function chaining, fan-out and fan-in, and optionally the Async HTTP API Pattern.

Scenario

To illustrate this pattern on Durable Functions, I will be using a fictitious cat model agency called Furry Models Australia. Furry Models is running a campaign to attract the most glamorous, attractive, and captivating cats in Australia. They will be receiving photos of all aspiring cats and they need a streamlined approval process to accept or reject those applications. Furry Models want to implement this in an agile manner with a short time-to-market and with a very cost-effective solution. They know that serverless is the way to go!

11 Join Us

Pre-requisites

To build this solution, we will need:

  • SendGrid account. Given that Azure Functions provides an output binding for SendGrid to send emails, we will be relying on this service. In case you want to implement this solution, you would need a SendGrid account. Once you sign up, you need to get your API Key, which is required for the Azure binding. You can get more information about the SendGrid binding for Azure Functions and how to use it here.
  • An Azure Storage Account: The solution requires a Storage Account with 3 blob containers: requestsapproved, and rejected. The requests container should have public access level so blobs can be viewed without a SAS token. For your own solution, you might want to make this more secure.

Solution Overview

The picture below shows an overview of the approval workflow solution I’ve build based on Durable Functions.

Pictures of the aspiring cats are to be dropped in an Azure storage blob container called requests. At the end of the approval workflow, pictures should be moved to the approved or rejected blob containers accordingly.

20 Solution Overview

The steps of the process are described as follows:

  1. The process is being triggered by an Azure Function with the BlobTrigger input binding monitoring the requests blob container. This function also implements the DurableOrchestrationClient attribute to instantiate a Durable Function orchestration
  2. The DurableOrchestrationClient starts a new instance of the orchestration.
  3. Then, the Durable Function orchestration calls another function with the ActivityTrigger input binding, which is in charge of sending the approval request email using the SendGrid output binding.
  4. SendGrid sends the approval request email to the (cat) user.
  5. Then, in the orchestration, a timer is created so that the approval workflow does not run forever, and in case no approval is received before the timer finishes the request is rejected.
  6. The (cat) user receives the email, and decides whether the aspiring cat deserves to join Furry Models or not, by clicking the Approve or Reject button. Each button has a link to an HttpTrigger Azure Function which expects the selection and the orchestration instanceId as query params
  7. The HttpTrigger function receives the selection and the orchestration instanceId. The function checks the status of the orchestration instance, if it’s not running, it returns an error message to the user. If it’s running, it raises an event to the corresponding orchestration instance.
  8. The corresponding orchestration instance receives the external event.
  9. The workflow continues when the external event is received or when the timer finishes; whatever happens first. If the timer finishes before a selection is received, the application is automatically rejected.
  10. The orchestration calls another ActivityTrigger function to move the blob to the corresponding container (approved or rejected).
  11. The orchestration finishes.

A sample of the email implemented is shown below.

22b Sample Email

The Solution

The implemented solution code can be found in this GitHub repo. I’ve used the Azure Functions Runtime v2. I will highlight some relevant bits of the code below, and I hope that the code is self-explanatory 😉:

TriggerApprovalByBlob.cs

This BlobTrigger function is triggered when a blob is created in a blob container and starts the Durable Function ochestration (Step 1 above)

OrchestrateRequestApproval.cs

This is the Durable Function orchestration which handles the workflow and is started by the step 2 above.

SendApprovalRequestViaEmail.cs

ActivityTrigger function which sends the approval request via email with the SendGrid output binding (Step 3 above).

ProcessHttpGetApprovals.cs

HttpTrigger function that handles the Http Get request initiated by the user selection (click) on the email (Step 7 above).

MoveBlob.cs

ActivityTrigger function that moves the blob to the corresponding container (Step 10 above).

local.settings.json

These are the settings which configure the behaviour of the solution, including the storage account connection strings, the SendGrid API key, templates for the email, among others. You would need to implement these as app settings when deploying to Azure

Wrapping up

In this post, I’ve shown how to implement an Approval Workflow (Human Interaction pattern) on Azure Durable Functions with SendGrid. Whether you wanted to learn more about Durable Functions, to implement a serverless approval workflow or you run a cat model agency, I hope you have found it useful 🙂 Please feel free to ask any questions or add your comments below.

Happy clouding!

Follow me on @pacodelacruz

Cross-posted on Deloitte Platform Engineering Blog

Ten-point checklist when migrating from BizTalk to Azure iPaaS (Logic Apps)

Summary

Business are evolving increasingly fast, and IT can be an enabler or a deterrent of this evolution. IT changes should always bring business value and never compromise core business needs.

As part of becoming more agile, a common concern for many of our customers is the transition from on-premises integration platforms to a cloud or hybrid solution, in particular migrating their BizTalk Server environments to the Microsoft Azure Integration Platform-as-a-Service (iPaaS), which is based on Azure Logic Apps.

There are a number of reasons you might want to consider migrating your BizTalk solutions to the Microsoft Azure iPaaS, including:

  1. Enabling or supporting the digital transformation journey. Azure services, like Logic Apps, Azure Functions and API Management allow you to expose and consume modern APIs, which are key enablers of digital transformation.
  2. Reducing your OpEx. Significantly reduce your IT operation and licensing costs by leveraging PaaS and serverless components.
  3. Gaining Agility: Azure allows you to deliver business value in weeks, instead of months. Not only because of the tooling but also because of the capabilities of the platform and availability of hundreds of connectors.
  4. Unlocking new business solutions: With Azure, new business solutions are possible. From asynchronous messaging of Service Bus to eventing of Event Grid, to smart solutions with Stream Analytics, Cognitive Services and Machine Learning, to monetisation of APIs with API Management, to advanced monitoring and alerting with OMS and Log Analytics, to name a few.

With all of that said, supporting your digital transformation leveraging integration can sometimes be challenging. Therefore, it’s imperative you start early, plan thoroughly and implement well to avoid unnecessary complications.

To get the full article, download the document from my employers site with the ten-point checklist to get your BizTalk to Azure iPaaS transition in good shape.