Mobile First Cloud First

A blog by Geert van der Cruijsen on Apps, Cloud & ALM

Category: Cloud

Setting up Continuous delivery for Azure API management with VSTS

Where Continuous delivery for web applications on Azure is becoming quite popular and common  I couldn’t find anything about settting this up for your API definitions in Azure API management. Since i had to set this up at my current customer I thought it was a good idea to share this in a blogpost so everyone can enjoy it. In this blogpost i’ll explain how you can set up Continuous delivery of your API definitions in Azure API management including the actual API implementation in Azure Web apps using VSTS (Visual Studio Team Services)

azure api management

First let me explain the architecture we use for our API landscape. As explained we use Azure API management for exposing the APIs to the outside world and we use Azure Web Apps for hosting the API implementation. These Web apps (Both .Net Core and Full framework .Net Web APIs) are hosted in an ASE (App Service Environment) so they are not exposed directly to the internet while we can still use all the cool things Azure Web Apps offer. These API web apps then connect to datastores hosted in Azure or connect to the on premise hosted environments through an express route or VPN.

To be able to set up our Continuous Delivery pipeline we have to arrange the following things.

  • Build your API implementation so we have a releasable package
  • Create infrastructure to host the API implementation
  • Deploy the API implementation package to the newly created infrastructure
  • Add API definition to Azure API management.
  • Repeat above steps for each environment. (DTAP)

Building your App

The first step can be different from my example if you’re not building your APIs using .Net technology. In our landscape we have a mix of APIs made with .Net Core and APIs made with .Net Full Framework because they needed libraries that were not available in .Net Core (yet). I’m not going into details on how to build your API using VSTS because i’ll assume  you’re already doing this or you know how to do this. If not here is a link to the official documentation.

One thing to keep in mind is that your API  web app does have to expose a API definition so Azure API Management can import this. We use Swashbuckle for this to automatically generate a swagger definition. If you’re using .Net Core you’ll have to use Swashbuckle.AspNetCore

Deploying the API implementation & adding it to Azure API management

For automating the deployments we’re going to the use Release Management feature of VSTS. In our first environment we’ll create steps to do all the things we described above.

 Screen Shot 2017-07-21 at 13.20.30

 The steps in our workflow are the following:

  1. Create web application infrastructure by rolling out an ARM template
  2. Set environment specific variables
  3. deploy the API implementation package
  4. Use a task group to add the API definition to Azure API management.

Creating the web app infrastructure & deploying the API Implementation package

the first and third steps are the basic steps of deploying a web application to Azure web apps. This is no different for APIs so i’ll just link to an existing blogpost here that explains these if you don’t know what they do.

Setting environment specific variables

the second task is a custom task created by my colleague Pascal Naber. It can help you overwrite specific variables you want to use in your environments by storing these settings as App Settings on your Azure web app. We use this to set the connection strings to backend systems for example a Redis Cache or a database.

Add API to API Management

So if we release the first 3 steps we would have an API that would on it’s own. But the main reason of this blogpost was that we want to have our API exposed through Azure API management so let’s have a look on how we can do that.

Azure API management has Powershell commands to interact with it and we can use this to add API definitions to Azure API management too. Below is a sample piece of Powershell that can import such an API definition from a Swagger file.

The script is built up out of 3 parts: first we retrieve the API management context by using the New-AzureRmApiManagementContext Commandlet. When we’ve gotten a context we can use this to interact with our API management instance. The second part is retrieving the swagger file from our running Web app through wget which is short for doing a GET web request. We’ll download the swagger file to a temporary disk location because in our case our web apps are running in an ASE  and therefore are not accessible through the Internet. if your web apps are connected to the internet you can also directly use the URL in the 3rd command to import the Swagger file into Azure API Management. Import-AzureRmApiManagementApi.

So now we have a script that we can use to import the API let’s add it to the VSTS release pipeline we could just add the powershell script to our source control and call the powershell using the build in powershell task. I’d like to make the developers’ life in our dev teams as easy as possible so i’m tried to abstract all Powershell mumbo jumbo away from them so they can focus on their APIs. To do this i’ve created a “Task Group” in VSTS containing this Powershell task so developers can just pick the “Add API to API Management Task” from the list in VSTS and supply the necessary parameters.

Screen Shot 2017-07-21 at 13.22.00

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When we add this task group to the release we can run our release again and the API should be added to Azure API Management.

 Screen Shot 2017-07-21 at 13.20.30

Success!! Our initial continuous delivery process is fixed. At my current client we have 4 different API management instances and we also deploy our APIs 4x. A Development, Test, Acceptance and Production instance. The workflow we created deploys the API to our development environment. We’ve set this up to be continuous so every time a build completes on the master branch we create a new release that will deploy a new API instance to Azure and will update our Development Azure API management instance.

We can now clone this environment 3x so we create a pipeline that will move from dev, test to acceptance and production. I always set the trigger to automatically after the previous environment is completed. if we run our release again we’ll have 4 API instances deployed and in all 4 Azure API management instances they corresponding API will be imported.

Now the only thing you have to add is optionally adding integration tests to the environment you prefer and you are ready to roll!

Screen Shot 2017-07-21 at 13.24.10

 

Happy Coding!

Geert van der Cruijsen

Created an open source VSTS build & release task for Azure Web App Virtual File System

I’ve created a new VSTS Build & Release task to help you interact with the (VFS) Virtual File System API (Part of KUDU API of your Azure Web App). Currently this task can only be used to delete specific files or directories from the web app during your build or release workflow. It will be updated in the near future to also be able to list files or to upload / download files through the VFS API.

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The reason i made this task was that i needed it at my current customer. We’re deploying our custom solution to a Sitecore website running on Azure web apps using MSDeploy. The deployment consists of 2 parts: an install of the out-of-the-box Sitecore installation and the deployment of our customisations. When deploying new versions we want to keep the Sitecore installation and MSDeploy will update most of our customisations. Some customisations however create artifacts that stay on the server and aren’t  in control of the MSDeploy package that can cause errors on our web application. This new VSTS Build / Release task can help you delete these files. In the future this task will be updated with other functionality of the VFS API such as listing, uploading or downloading files.

The task is available in the VSTS Marketplace and is open source on github.

Let’s have a look how to use this task and how it works under the hood.
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Adding an Azure web app to an Application Service Environment running in another subscription

Web apps and Api apps  in Azure are great, however when using them you have to agree to have them connected to the internet directly without the possibility of adding a WAF or other kind of additional protection (next to the default Azure line of defense). When you want to add something like that you have to add an Internal Application Service Environment to host your apps so you can control the network access to these apps.

App Service

However adding an Application Service Environment is quite costly if you are only running a few apps in them. (Minimum requirements for an Application Service Environment are 2 P2’s and 2 P1’s to run the Application Service Environment (ASE)

In our case adding an ASE was fine except that we have a scenario where we have quite a lot of subscriptions and most of them are quite small running only a couple of apps in them. Adding an ASE for each subscription was going to become a bit to costly so we came up with the idea of creating 1 central subscription called “Shared Services” where we would host things that multiple departments could share such as WAF functionality, the VNet, the Express route and also the ASE.

After creating the design we ran in to some problems actually implementing it because we weren’t able to select an ASE in another subscription which was part of the same enterprise agreement when creating an App Service Plan or Web App in Azure.  After checking it seems that this is a limitation of the Azure Portal and we had to use ARM templates to create our web app. This didn’t matter because we were planning on using ARM templates anyway. so we started to give it a try.

At first we had some trouble adding the ASE as our hosting environment. we tried adding the “HostingEnvironment” to point to the name of the ASE in our other subscription but this did not work and we kept receiving errors like “Cannot find HostingEnvironment with name *HostingEnvironmentName*. (Code: NotFound)”

ASE erorr message

 

After that we tried to remove the “HostingEnvironment” property and only set the “HostingEnvironmentID” to directly link to the full resourceID of our ASE. this did get our hopes up because we were able to deploy the web app, however it was running on the P1’s that were part of the workerpool of our internal ASE but it still had a public dns name and was accessible from the internet. I guess we weren’t supposed to created it this way. so i asked help from the Microsoft product team and they pointed me to the right correction.

It all boils down to using a newer API version of the Web App and App Service Plan ARM template API than that are generated in visual studio when building ARM templates. we had to use apiVersion: 2015-08-01

in here we can set the “hostingEnvironmentProfile” to the full resourceID of our ASE for both the App Service Plan as the Web App. Next to that we also have to set the sku to the correct worker pool within our ASE.

Now when we try to deploy our ARM template it will actually create an App Service Plan and Web App in another subscription than where our ASE is running. Nice!

Hopefully this post will help you when you run in to the same problems i did when trying to deploy web apps in an ASE using ARM templates.

Happy Coding / Deploying

Geert van der Cruijsen