How to convert HTML to PDF in Azure Functions with Azure Premium plan using Blink?

The Syncfusion® HTML to PDF converter is a .NET Core library for converting webpages, SVG, MHTML, and HTML files to PDF using C#. It uses the popular rendering engine Blink (Google Chrome). It is reliable and accurate. The result preserves all graphics, images, text, fonts, and the layout of the original HTML document or webpage.

Using this library, you can convert any HTML strings, URLs, or web pages to PDF in the Azure Functions with Azure Premium plan in Linux.

Steps to convert HTML to PDF in the Azure Premium plan Blink rendering engine:

1. Create the Azure function project.

2. In the project configuration window, name your project and select the Create option. Then Select the Azure Functions type and .NET Core version.

3. Install the Syncfusion.HtmlToPdfConverter.Net.Linux NuGet package as a reference to your .NET Core Azure function application from the NuGet.org.

4. Include the following namespaces in Function1.cs file.

   using Syncfusion.HtmlConverter;
   using Syncfusion.Pdf;
   using System.Runtime.InteropServices;
   

5. Add the following code sample in the Function1 class to convert HTML to PDF using the Blink rendering engine in the Azure Functions Linux Premium.

   [FunctionName("Function1")]
   public static async Task<IActionResult> Run([HttpTrigger(AuthorizationLevel.Function, "get", "post", Route = null)] HttpRequest req, ILogger log, ExecutionContext executionContext)
   {
   string blinkBinariesPath = string.Empty;
   MemoryStream ms = new MemoryStream();
   log.LogTrace(blinkBinariesPath);
    blinkBinariesPath = SetupBlinkBinaries(executionContext);
    InstallLinuxPackages(executionContext.FunctionAppDirectory);
    //string url = req.Query["url"];
    
   //Initialize the HTML to PDF converter with the Blink rendering engine.    HtmlToPdfConverter htmlConverter = new HtmlToPdfConverter(HtmlRenderingEngine.Blink);
    BlinkConverterSettings settings = new BlinkConverterSettings();
    
   //Set command line arguments to run without sandbox.
   settings.CommandLineArguments.Add("--no-sandbox");
   settings.CommandLineArguments.Add("--disable-setuid-sandbox");
    settings.BlinkPath = blinkBinariesPath;
   //Assign Blink converter settings to the HTML converter. 
   htmlConverter.ConverterSettings = settings;
    
   //Convert URL to PDF.
   PdfDocument document = htmlConverter.Convert("https://www.syncfusion.com");
    
   //Save and close the PDF document. 
   document.Save(ms);
   document.Close();
   ms.Position = 0;
   return new FileStreamResult(ms, "application/pdf");
    }
   

6. Add the following helper methods to copy and set permission to the BlinkBinariesLinux folder.

private static string SetupBlinkBinaries(ExecutionContext executionContext)
{            
string blinkAppDir = Path.Combine(executionContext.FunctionAppDirectory, "bin/runtimes/linux/native");
string tempBlinkDir = Path.GetTempPath();
string chromePath = Path.Combine(tempBlinkDir, "chrome");
            
if (!File.Exists(chromePath))
{
CopyFilesRecursively(blinkAppDir, tempBlinkDir);
 SetExecutablePermission(tempBlinkDir);
 }
return tempBlinkDir;
}
 
private static void CopyFilesRecursively(string sourcePath, string targetPath)
 {
//Create all the directories from the source to the destination path.
foreach (string dirPath in Directory.GetDirectories(sourcePath, "*", SearchOption.AllDirectories))
{
 Directory.CreateDirectory(dirPath.Replace(sourcePath, targetPath));
}
 
 //Copy all the files from the source path to the destination path.
 foreach (string newPath in Directory.GetFiles(sourcePath, "*.*", SearchOption.AllDirectories))
{
 File.Copy(newPath, newPath.Replace(sourcePath, targetPath), true);
}
}
 
[DllImport("libc", SetLastError = true, EntryPoint = "chmod")]
internal static extern int Chmod(string path, FileAccessPermissions mode);
 
private static void SetExecutablePermission(string tempBlinkDir)
{
FileAccessPermissions ExecutableFilePermissions = FileAccessPermissions.UserRead | FileAccessPermissions.UserWrite | FileAccessPermissions.UserExecute |
FileAccessPermissions.GroupRead | FileAccessPermissions.GroupExecute | FileAccessPermissions.OtherRead | FileAccessPermissions.OtherExecute;
 
string[] executableFiles = new string[] { "chrome", "chrome_sandbox" };
foreach (string executable in executableFiles)
{
var execPath = Path.Combine(tempBlinkDir, executable);
 
if (File.Exists(execPath))
{
var code = Function1.Chmod(execPath, ExecutableFilePermissions);
if (code != 0)
{
throw new Exception("Chmod operation failed");
}
}
}
}

7. Include the below Enum in the Function1.cs file.

   [Flags]
   internal enum FileAccessPermissions : uint
   {
   OtherExecute = 1,
   OtherWrite = 2,
   OtherRead = 4,
    
   GroupExecute = 8,
   GroupWrite = 16,
   GroupRead = 32,
    
   UserExecute = 64,
   UserWrite = 128,
   UserRead = 256
   }
   

8. The Azure Function app is currently in read-only mode, and the external files do not have the authorization to execute while the function app is being deployed. To get around this limitation, we moved the requirements shell file to a temporary directory and then granted sufficient execute access to install the Linux package.

   private static void InstallLinuxPackages(string functionAppDirectory)
   {
   if (!RuntimeInformation.IsOSPlatform(OSPlatform.Linux))
   {
    return;
   }
    FileAccessPermissions ExecutableFilePermissions = FileAccessPermissions.UserRead | FileAccessPermissions.UserWrite | FileAccessPermissions.UserExecute |
   FileAccessPermissions.GroupRead | FileAccessPermissions.GroupExecute | FileAccessPermissions.OtherRead | FileAccessPermissions.OtherExecute;
    
   //Install the dependencies packages for HTML to PDF conversion in Linux
   string shellFilePath = Path.Combine(functionAppDirectory, "data");
   string tempBlinkDir = Path.GetTempPath();
   string dependenciesPath = Path.Combine(tempBlinkDir, "dependenciesInstall.sh");
   if (!File.Exists(dependenciesPath))
   {
   CopyFilesRecursively(shellFilePath, tempBlinkDir);
   var execPath = Path.Combine(tempBlinkDir, "dependenciesInstall.sh");
    
   if (File.Exists(execPath))
   {
   var code = Function1.Chmod(execPath, ExecutableFilePermissions);
   if (code != 0)
   {
   throw new Exception("Chmod operation failed");
   }
   }
   Process process = new Process
   {
   StartInfo = new ProcessStartInfo
   {
   FileName = "/bin/bash",
   Arguments = "-c " + execPath,
   CreateNoWindow = true,
    UseShellExecute = false,
   }
   };
   process.Start();
   process.WaitForExit();
   }
   }
   

9. Set Copy to Output Directory as “Copy if newer” to the dependenciesInstall.sh file.

Publish to Azure Functions Linux

Follow the given steps to publish to Azure Functions Linux:

1. Right-click the project and select Publish. Then, create a new profile in the Publish Window and you can create the Azure Function App service with a Premium plan.

2. Select existing or create a new Azure function.

3. After creating the profile, click the Publish button.

4. Now, go to the Azure portal and select the App Services. After running the service, click Get function URL > Copy.

   Then, paste it into the new browser tab. You will get the PDF document as follows:

A complete working sample can be downloaded from the HTML to PDF Azure Premium.

Take a moment to peruse the documentation where you can find converting HTML pages to PDF documents along with respective customization options and features. Click here to explore the rich set of Syncfusion Essential® PDF features.

An online sample link to convert HTML to PDF.