Setting Up Let’s Encrypt on an Azure App Service

Once I had my blog ported over to WordPress running as an Azure App Service, I knew I needed to figure out how to secure my site, both because I wouldn’t want to be logging into it, randomized unique password or not, and because I wanted to be a good web citizen and secure all the things.

I saw that my pal Jeramiah had used Let’s Encrypt to secure his site, so I did some Googling, and asked him if he’d used the Azure extension I’d seen mentioned in a few blog posts, and he confirmed he had.

I read a few guides on getting it done, and while I had a few issues along the way, I finally got everything working. In an effort to save people from the starting and stopping and Googling that I had to go through while working through it, I decided to document the entire process from start to finish on a fresh blog.

You’re going to need an Azure Storage Account

Once you’re logged into the Azure portal, look for Storage accounts on the left-hand menu.

Azure Storage Account 1

As you can see here, I have no storage accounts. Click Create storage account.

Azure Storage Account 2

You’ll need to fill out and select some options here. I like to name every account or aspect of an App Service based on the overall name of the App Service, so I went with geekfoodblog.

I left Resource Manager as the default, selected general purpose v1, located in East US, and selected Geo-redundant storage (GRS). That may be overkill for my needs, but based on the storage costs for this blog last month and the amount of MSDN credit I have, it’s moot.

I believe Secure transfer required was Disabled by default, and I left it that way. If you have more than one subscription, you can select that here.

I did choose to drop it into the existing geekfoodblog Resource Group, since I had already deployed WordPress as an App Service before setting up Let’s Encrypt.

I did not choose to configure  virtual networks, nor did I pin this account to my dashboard, and with that, I clicked Create.

Azure Storage Account 3

Click on Access keys and copy your primary Connection String into a secure note somewhere for later use.

Azure Storage Account 4

Now you need a Service Account (or App Registration)

You may see this referred to elsewhere as a Service Principal. Azure calls it an App Registration. So click on Azure Active Directory, then App registrations, and then New application registration.

Azure Service Principal 1

You can see how I named mine. You’ll make use of auto-complete later, so using a few memorable letters as a prefix helps.

Also, as noted below, the Sign-on URL doesn’t matter in the sense that it doesn’t have to be something you own or are working with, but it does has to be something that is recognized as a legitimate URL.

Azure Service Principal 2

Now you’ll need to create a client secret or key.  Click Settings, then Keys.

Azure Service Principal 3

Give your key a description – I used letsencrypt, and I selected Never expires as the duration. That’s probably terrible, but it’s a huge key, so sue me.

When you click Save, you will be warned to copy the key value, as you won’t be able to retrieve it later. Stick that in the same secure note with your Storage Account connection string from above.

Azure Service Principal 4

You’ll also want to copy and paste the Client ID of your Service Account / App Registration.

As you can see below, and as you’ll notice in the screenshot I saved with the Client ID error I left in, the Client ID is not what you named the App Registration, but rather the Application ID.

You can copy and paste this into your secure note, or you can go grab it later as I did.

App Registration App-Client ID

Time to assign permissions for your Resource Group to your Service Account

Now you need to make sure your Service Account has permissions to your Resource Group, in particular so it can access the Storage Account you created above.

Click on Resource groups, then on the Resource Group of which your Storage Account is a member.

Azure Service Principal 5

Click on Access control (IAM), then click Add. For Role, select Contributor.

Start entering the name of your Service Account in the Select field, and select it, then click Save.

Azure Service Principal 6

Azure Service Principal 7

Now let’s install the Let’s Encrypt Extension

But first, so you can avoid an issue I noticed when I first set this up, let’s ensure your App Service is configured to always be on.

Click on App Services, then click on your App Service.

Azure Extension 1

Now click on Application Settings, and scroll down to Always On and make sure it is set to On.

Mine was not for some reason, and I noticed an error at one point.

Azure Extension 2

Now click on Extensions, then Add.

Azure Extension 3

Look for Azure Let’s Encrypt by SJKP. Click on it, then OK to accept legal terms, then OK again.

Azure Extension 4

Before proceeding, to help you avoid an issue I’ll show with a screenshot later, go ahead and restart your App Service.

Scroll up to click Overview, then click Restart. Then scroll back to and click Extensions.

Restart Service

Click on Azure Let’s Encrypt, then click Browse.

Azure Extension 5

Azure Extension 6

If you didn’t restart your App Service, you might get this error below.

Azure Extension 7

Now fill out the Let’s Encrypt Authentication Settings

First you’ll enter your Tenant URL, which will be unique to your Azure tenant.

You’ll then add your Azure SubscriptionID – also unique to you.

Next, for ClientID, you’ll enter the Application ID of the Service Account / App Registration you created above. Did you copy and paste that into your secure note? If not, you can find it under Azure Active Directory > App Registrations > Name of your Service Account.

For ClientSecret, enter the Secret / Key from your Service Account / App Registration.

Enter your ResourceGroupName and ServicePlanResourceGroupName – which for me are the same thing.

Be sure to check Update Application Settings, as this is required for the web job that will renew the certificate later.

Azure Extension 8

At this point, assuming you already have your hostnames configured, you should see something similar to what I did below. So click Next.

Azure Extension 9 Azure Extension 10

Select the hostname, enter your email address, and click Request and Install certificate. 

I’d already done this once before, so I was fairly sure it would work, so I didn’t bother checking the UseStaging box.

Azure Extension 11

Now you’ll need to add the SSL binding to your Azure-hosted domain. So go to App Services Your App ServiceCustom Domains.

While you’re here, if you haven’t already done it, switch HTTPS Only to On.

Scroll down and click Add binding next to your domain

Azure Extension 12

Select your custom domain under Hostname. Select the new SSL certificate under Certificate. Click Add Binding.

Azure Extension 13

Time for some Azure WebJobs goodness

If you stopped right now, your site would be secured until the Let’s Encrypt SSL certificate expired in 3 months. Let’s ensure that doesn’t happen by connecting your Let’s Encrypt WebJob to the Azure Storage Account you created above.

Go to App Services Your App ServiceApplication Settings.

Scroll down to Connection Strings and create AzureWebJobsDashboard and AzureWebJobsStorage.

Both of these should have a value of, you guessed it, the Connection String you copied from your Azure Storage Account above.

Azure Extension 14

You can confirm your WebJob is running by going to App Services Your App ServiceWebJobs

Azure Extension 15

And once you’ve done all this, fire up your web browser, go to your custom domain, and check your your shiny new Let’s Encrypt SSL certificate.

Azure Extension 16

5 thoughts on “Setting Up Let’s Encrypt on an Azure App Service”

  1. Thanks a lot for this, I just moved from one tenant to another and I had to reconfigure this thanks to you it goes smoothly again 🙂

  2. Thanks for writing this – had previously set this up and lost track of where. If there’s an update to the Let’s Encrypt extention is seems to stop working.

    Re-following steps in this guide reminded me how I’d set it up 2 years ago 🙂 Thanks.

  3. Hi Mike Stanley,
    I tried creating it from scratch following the instructions you posted above.
    As a result, was able to create SSL successfully.
    However, it looks like the SSL was generated not by Let’s Encrypt, , but by the ESET SSL Filter CA.
    Sorry but is that correct?

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