Azure Websites Slots and Configuration

One of the conundrums we have with deploying sites to test means that there is often a lot of configuration that is needed on a test site that is different to a live site. There is also the time and risk of deploying a new instance into the production sites once testing has completed.

Azure websites has introduced deployments slots which allows you to have multiple deployments and swap between them in a similar way you could do with the production and staging slots in cloud services. Websites has the added advantage that you can have more than two slots and you can call them whatever you want.

One approach we are looking at to ensure consistency with what is deployed is to configure up a number of slots on the website for a variety of uses e.g. Production, Staging, UAT. The issue with having multiple slots is that there are often sets of configurations that are required to ensure that each slot will work with the correct backend. By default all configuration stored in the appsettings in web.config will move with the slot. Details of the exact configuration settings that move with the deployment can be found here (http://azure.microsoft.com/en-gb/documentation/articles/web-sites-staged-publishing/)

For example, in my web.config file I have the following setting

<appSettings>

<add key=”about” value=”This is the web.config text” />

</appSettings>

This setting can be overridden in the Azure portal(s) and these by default will follow the deployment and not stay with the slot.

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So in this example the “about” config will be set to “This is Now the Staging slot” and when the staging slot is swapped to be production, the new production configuration will also be “This is Now the Staging slot”

This is not necessarily what you want on production. Websites has a feature, that is currently unsupported by the management portal(s), which allows specific configuration items to become sticky i.e. they stay with the slot. There is a powershell cmdlet which allows individual appsettings to be marked as sticky and remain with the slot regardless of the deployment that is in the slot and they will also remain in the slot when the slots are swapped.

This can be set for both Appsettings and connection strings by running the following commands

Set-AzureWebsite -Name somesite -SlotStickyAppSettingNames @(“about”, “another_config_key”)

Set-AzureWebsite -Name somesite -SlotStickyConnectionStringNames @(“a_connection_string”, “some_other_connectionstring”)

After running the commands the example above will still have the configuration setting above, but once the deployment is swapped from the staging slot to production the configuration will remain on the staging slot.

This approach should now allow us to deploy to a UAT slot with UAT configuration and allow the customer to test, when they are happy we can move the same deployment that has just been tested to the staging slot with production configuration and be tested in isolation to live to ensure that it works. When you are happy that the staging slot is working this can then be swapped out to production.

For a more detailed introduction to slots and configuration see:

http://azure.microsoft.com/en-gb/documentation/articles/web-sites-staged-publishing/

http://blog.amitapple.com/post/2014/11/azure-websites-slots/#.VG22ik1yaAg

Moving an Azure Website to a separate set of Virtual Machines

When an Azure Website is created and is in production it will most likely be running in a Standard or Basic configuration. These are both sets of Virtual Machines and can be shared across your websites. In the old portal you could only scale the group of websites together but the new Azure Management portal now allows you to move your websites on to different virtual machines so that if one site is more heavily loaded than others it can be scaled out separately if required. The set of virtual machines is known as a Web Hosting Plan. If you want to move one or more of your websites to a different set of virtual machines then you will need to create a new web hosting plan for this.

In the new portal click on “Browse” in the left hand bar

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This brings up the Browse Menu.

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Select “Web hosting plans”

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You can see that I only have 1 web hosting plan and it is currently hosting two websites. I would like to move them onto separate virtual machines so that I can scale them out independently.

To do this I need to navigate to the web site I wish to move.

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The top menu needs to be expanded by clicking the 3 dots on the right of the menu bar. this then displays the web hosting plan button.

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Clicking this displays the web hosting plan associated with this web site

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Clicking on the new hosting plan option allows you to create a new plan

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I’ve selected a standard small instance to host my website.

After clicking OK the new hosting plan will be created and the website moved to it. After a short while you should see that the hosting plan has changed in this website as well.

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Note: you now have two hosting plans both of which will be a separate billing entity. I am also led to believe that if you move everything off of a hosting plan you will still be charged for it.Hosting plans can be deleted once all the websites have been moved off of it. This is done in the Web hosting plan page. right click on the plan you want to delete and select the Delete option

5 Tips for using Azure Web Jobs

1. Use public on the main program class.In order for web jobs to initialise correctly the main class that contains the web jobs needs to be made public. Once this has been added the individual jobs can then be read and should be visible in the output when running locally.

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2. In order to store and view the invocation details for each web job you need to configure AzureWebJobsDashboard in the configure tab of the website you have deployed the web job to. Even if you have configured this in your app.config file.

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If this is not configured in the website then you will receive the following error when you try and view the web jobs dashboard

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3. Debug using Visual Studio. Once of the nice features of the web jobs SDK is the ability to run and debug the web job locally in Visual Studio. Following the Getting Started guide, you create a console application which you can debug in Visual Studio before deploying it to Azure

4. User TextWriter for debugging. The Azure Web Jobs SDK (see the logging section) provides a mechanism to log out information that can be viewed through the Azure Web jobs dashboard. By adding a TextWriter as an input parameter to your web job method, you can use WriteLine to then output information you wish to log.

5. Make your Blob Triggers more efficient by triggering them using BlobOutput. The mechanism that the BlobInput trigger uses has a 10-20 minute lag before the trigger can fire, but each time BlobOutput is used it triggers a rescan for Blob input.

“There is an optimization where any blob written via a [BlobOutput] (as opposed to being written by some external source) will optimistically check for any matching [BlobInputs],” See How does [BlobInput] work?. Storage Queues and Service Bus topics and Queues are generally processed within seconds so if you can use a queue to trigger a BlobOutput then use this to trigger any subsequent BlobInputs

Azure Service Bus Event Hub Firewall Port

I’m investigating the Azure Service Bus Event Hub using the getting started tutorial and I didn’t seem to be able to receive any data. It turns out that our firewall was blocking an outbound port. After some investigation I found a post which hinted at a port for the on premise service bus. Our IT guys kindly enabled the outbound port 5671 and I now can receive data from the event hub.

For completeness the following site has details of the other firewall ports required for service bus : http://msdn.microsoft.com/en-us/library/ee732535.aspx