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How to Use IronWord on AWS Lambda

Kye Stuart

Updated:August 20, 2025

This article provides a comprehensive guide to setting up an AWS Lambda function using IronWord. You will learn how to configure IronWord to create and manipulate Word documents within an AWS Lambda environment.

Installation

Since this example will read/write Word documents to an S3 bucket, the AWSSDK.S3 NuGet package is required.

Using IronWord ZIP Package on AWS Lambda

When using the IronWord ZIP package, it’s important to set a temporary deployment path because AWS Lambda has a read-only filesystem except for the /tmp/ folder. You must configure IronWord to use this folder for its runtime files:

var awsTmpPath = @"/tmp/";
IronSoftware.Word.Installation.DeploymentPath = awsTmpPath;

var awsTmpPath = @"/tmp/";
IronSoftware.Word.Installation.DeploymentPath = awsTmpPath;

Dim awsTmpPath = "/tmp/"
IronSoftware.Word.Installation.DeploymentPath = awsTmpPath

Integrating IronWord with AWS

Create an AWS Lambda Project

Use Visual Studio to create a containerized AWS Lambda project:

1. Install the AWS Toolkit for Visual Studio
2. Select AWS Lambda Project (.NET Core - C#)
3. Choose the .NET 8 (Container Image) blueprint and finish the setup
4. Select container image as the deployment type

Add Package Dependencies

Add IronWord and AWSSDK.S3 packages to your project via NuGet. The IronWord library works smoothly on AWS Lambda with the correct setup. Run the following command to install IronWord to your AWS project seamlessly:

Install-Package IronWord

Update your project's Dockerfile to use the .NET 8 Lambda base image and copy your build artifacts:

FROM public.ecr.aws/lambda/dotnet:8

RUN dnf update -y

WORKDIR /var/task

COPY "bin/Release/lambda-publish"  .

Modify the FunctionHandler Code

Below is an example Lambda function that creates a simple Word document, saves it as a .docx file, and uploads it to an S3 bucket.

using Amazon.Lambda.Core;
using Amazon.S3;
using Amazon.S3.Model;
using IronWord;
using IronWord.Models;
using System.Text;

// Assembly attribute to enable the Lambda function's JSON input to be converted into a .NET class.
[assembly: LambdaSerializer(typeof(Amazon.Lambda.Serialization.SystemTextJson.DefaultLambdaJsonSerializer))]

namespace IronWordAwsLambda;

public class Function
{
    private static readonly IAmazonS3 _s3Client = new AmazonS3Client(Amazon.RegionEndpoint.APSoutheast1);

    public async Task FunctionHandler(ILambdaContext context)
    {
        var awsTmpPath = @"/tmp/";
        License.LicenseKey = "YOUR-LICENSE-KEY"; // Replace if you have one

        string filename = Guid.NewGuid() + ".docx";
        string localPath = Path.Combine(awsTmpPath, filename);
        string bucketName = "your-s3-bucket-name";
        string objectKey = $"IronWordAwsLambda/{filename}";

        try
        {
            // Create Word Document
            var doc = new WordDocument();
            Paragraph paragraph = new Paragraph(new TextContent("Hello from IronWord on AWS Lambda!"));
            doc.AddParagraph(paragraph);
            doc.SaveAs(localPath);

            context.Logger.LogLine("Word document created.");

            // Upload to S3
            byte[] fileBytes = await File.ReadAllBytesAsync(localPath);
            await UploadToS3Async(bucketName, objectKey, fileBytes);

            context.Logger.LogLine($"Document uploaded to S3: {bucketName}/{objectKey}");
        }
        catch (Exception ex)
        {
            context.Logger.LogLine($"[ERROR] {ex.Message}");
        }
    }

    private async Task UploadToS3Async(string bucketName, string objectKey, byte[] fileBytes)
    {
        using var stream = new MemoryStream(fileBytes);
        var request = new PutObjectRequest
        {
            BucketName = bucketName,
            Key = objectKey,
            InputStream = stream,
            ContentType = "application/vnd.openxmlformats-officedocument.wordprocessingml.document"
        };
        await _s3Client.PutObjectAsync(request);
    }
}

using Amazon.Lambda.Core;
using Amazon.S3;
using Amazon.S3.Model;
using IronWord;
using IronWord.Models;
using System.Text;

// Assembly attribute to enable the Lambda function's JSON input to be converted into a .NET class.
[assembly: LambdaSerializer(typeof(Amazon.Lambda.Serialization.SystemTextJson.DefaultLambdaJsonSerializer))]

namespace IronWordAwsLambda;

public class Function
{
    private static readonly IAmazonS3 _s3Client = new AmazonS3Client(Amazon.RegionEndpoint.APSoutheast1);

    public async Task FunctionHandler(ILambdaContext context)
    {
        var awsTmpPath = @"/tmp/";
        License.LicenseKey = "YOUR-LICENSE-KEY"; // Replace if you have one

        string filename = Guid.NewGuid() + ".docx";
        string localPath = Path.Combine(awsTmpPath, filename);
        string bucketName = "your-s3-bucket-name";
        string objectKey = $"IronWordAwsLambda/{filename}";

        try
        {
            // Create Word Document
            var doc = new WordDocument();
            Paragraph paragraph = new Paragraph(new TextContent("Hello from IronWord on AWS Lambda!"));
            doc.AddParagraph(paragraph);
            doc.SaveAs(localPath);

            context.Logger.LogLine("Word document created.");

            // Upload to S3
            byte[] fileBytes = await File.ReadAllBytesAsync(localPath);
            await UploadToS3Async(bucketName, objectKey, fileBytes);

            context.Logger.LogLine($"Document uploaded to S3: {bucketName}/{objectKey}");
        }
        catch (Exception ex)
        {
            context.Logger.LogLine($"[ERROR] {ex.Message}");
        }
    }

    private async Task UploadToS3Async(string bucketName, string objectKey, byte[] fileBytes)
    {
        using var stream = new MemoryStream(fileBytes);
        var request = new PutObjectRequest
        {
            BucketName = bucketName,
            Key = objectKey,
            InputStream = stream,
            ContentType = "application/vnd.openxmlformats-officedocument.wordprocessingml.document"
        };
        await _s3Client.PutObjectAsync(request);
    }
}

Imports Amazon.Lambda.Core
Imports Amazon.S3
Imports Amazon.S3.Model
Imports IronWord
Imports IronWord.Models
Imports System.Text

' Assembly attribute to enable the Lambda function's JSON input to be converted into a .NET class.
<Assembly: LambdaSerializer(GetType(Amazon.Lambda.Serialization.SystemTextJson.DefaultLambdaJsonSerializer))>

Namespace IronWordAwsLambda

	Public Class [Function]
		Private Shared ReadOnly _s3Client As IAmazonS3 = New AmazonS3Client(Amazon.RegionEndpoint.APSoutheast1)

		Public Async Function FunctionHandler(ByVal context As ILambdaContext) As Task
			Dim awsTmpPath = "/tmp/"
			License.LicenseKey = "YOUR-LICENSE-KEY" ' Replace if you have one

			Dim filename As String = Guid.NewGuid().ToString() & ".docx"
			Dim localPath As String = Path.Combine(awsTmpPath, filename)
			Dim bucketName As String = "your-s3-bucket-name"
			Dim objectKey As String = $"IronWordAwsLambda/{filename}"

			Try
				' Create Word Document
				Dim doc = New WordDocument()
				Dim paragraph As New Paragraph(New TextContent("Hello from IronWord on AWS Lambda!"))
				doc.AddParagraph(paragraph)
				doc.SaveAs(localPath)

				context.Logger.LogLine("Word document created.")

				' Upload to S3
				Dim fileBytes() As Byte = Await File.ReadAllBytesAsync(localPath)
				Await UploadToS3Async(bucketName, objectKey, fileBytes)

				context.Logger.LogLine($"Document uploaded to S3: {bucketName}/{objectKey}")
			Catch ex As Exception
				context.Logger.LogLine($"[ERROR] {ex.Message}")
			End Try
		End Function

		Private Async Function UploadToS3Async(ByVal bucketName As String, ByVal objectKey As String, ByVal fileBytes() As Byte) As Task
			Dim stream = New MemoryStream(fileBytes)
			Dim request = New PutObjectRequest With {
				.BucketName = bucketName,
				.Key = objectKey,
				.InputStream = stream,
				.ContentType = "application/vnd.openxmlformats-officedocument.wordprocessingml.document"
			}
			Await _s3Client.PutObjectAsync(request)
		End Function
	End Class
End Namespace

Increase Memory and Timeout

Since document processing can be memory-intensive, increase your Lambda function memory to at least 512 MB and timeout to 300 seconds in aws-lambda-tools-defaults.json:

{
  "function-memory-size": 512,
  "function-timeout": 300
}

If you encounter errors like Runtime exited with error: signal: killed, increase memory or optimize your code.

Publish

To publish your Lambda function:

• Right-click your project in Visual Studio
• Select Publish to AWS Lambda...
• Follow the wizard and configure settings as needed

Try It Out!

Invoke the Lambda function through the AWS Lambda Console or Visual Studio. After execution, check your S3 bucket for the newly created Word document.

Kye Stuart

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Technical Writer

Kye Stuart merges coding passion and writing skill at Iron Software. Educated at Yoobee College in software deployment, they now transform complex tech concepts into clear educational content. Kye values lifelong learning and embraces new tech challenges.

Outside work, they enjoy PC gaming, streaming on Twitch, and ...Read More