In early this year, I am upgrading my Captcha library, the code that renders text on images blow up when running under Azure App Service for Linux. I can tell from the error message that the font I am using is not installed on Azure App Service's hosting machine. To fix this, I need to find out what fonts are there in Azure App Service for Linux. Let's see how to do it.

Solution 1

Since I can deploy code to Azure App Service. I am able to get font list and output on web page. Example code below is ASP.NET Core using SixLabors.ImageSharp.Drawing package.

    var fonts = SystemFonts.Collection.Families;

<h5>System Fonts</h5>
    @foreach (var item in fonts)


Now I am able to fix the captcha library on Azure App Service for Linux using either one of the system fonts.

Solution 2

This is a much simpler way if you don't want to write code and deploy to App Service. Just enter "SSH" in your App Service's blade.

Then run

cd /usr/share/fonts

We can get the same result.