Running in Docker Leave feedback

This guide shows how to run GroupDocs.Viewer for Node.js via Java inside a Docker container using a minimal example.

• Linux containers are recommended and fully supported.
• Ensure adequate fonts are installed in the container for accurate text layout.
• For Metered licensing, outbound internet access is required to report consumption. File-license mode works fully offline.

We are going to build the Docker image in two stages to minimize the final image size. In the first stage we build the application, and in the second stage we run it.

The key dependencies for the build stage are Node.js, JDK (Java Development Kit), and build tools. The final runtime stage requires only Node.js and JRE (Java Runtime).

This is a practical example showing how to render a document in a Docker container using the sample code. The final Docker image can be run as an application by passing the source file for rendering, the output file name, and an optional license file. See the Temporary License page for more details.

Note

You can download this sample application from here.

📂 basic-example/
├── 📂 work/                           
│   ├── 📄 sample.pdf                  # Input document to render
│   └── 📄 GroupDocs.Viewer.lic        # The license file (optional)
├── 📄 .dockerignore                   # Files to exclude from Docker build context
├── 📄 Dockerfile                      # Docker container definition
├── 📄 package.json                    # Node.js project file
├── 📄 render-file.js                  # Main application code
└── 📄 README.md                       # App readme

Let’s look at the most essential parts of the application:

import { Viewer, License, HtmlViewOptions } from '@groupdocs/groupdocs.viewer';

// Get the input file, output path, and license paths from the command line arguments
const [inputPath, outputPath, licensePathArg] = process.argv.slice(2);

// Get the license path from the command line arguments or the environment variable
const licensePath = licensePathArg || process.env.GROUPDOCS_LICENSE_PATH;
if (licensePath) {
	const license = new License();
	license.setLicense(licensePath);
}

// Create a new viewer instance
const viewerInstance = new Viewer(inputPath);

// Render the file to HTML
const viewOptions = HtmlViewOptions.forEmbeddedResources(outputPath + '/page_{0}.html');
viewerInstance.view(viewOptions);

{
  "name": "GroupDocs.Viewer for Node.js via Java Example",
  "version": "1.0.0",
  "type": "module",
  "private": true,
  "main": "render-file.js",
  "license": "MIT",
  "scripts": {
    "start": "node render-file.js",
    "dev": "node render-file.js"
  },
  "engines": {
    "node": ">=20"
  },
  "dependencies": {
    "@groupdocs/groupdocs.viewer": "^25.12.0"
  }
}

# Build stage – compiles native module and installs dependencies
FROM node:20-bullseye AS build
RUN apt-get update && apt-get install -y \
    openjdk-17-jdk-headless \
    build-essential

# Clean up cache
RUN rm -rf /var/lib/apt/lists/*

# Set JAVA_HOME and update PATH
ENV JAVA_HOME=/usr/lib/jvm/java-17-openjdk-amd64
ENV PATH=$JAVA_HOME/bin:$PATH

# Set working directory
WORKDIR /app

# Copy package files
COPY package*.json ./

# Install dependencies
RUN npm install --omit=dev

# Copy the rest of the app
COPY . .

# Final stage – slim runtime image
FROM node:20-bullseye-slim AS final

# Install Java runtime
RUN apt-get update && apt-get install -y \
    openjdk-17-jre-headless  
    
# Clean up cache
RUN rm -rf /var/lib/apt/lists/*

# Set JAVA_HOME and update PATH
ENV JAVA_HOME=/usr/lib/jvm/java-17-openjdk-amd64
ENV PATH=$JAVA_HOME/bin:$PATH

# Set working directory
WORKDIR /app

# Copy built application and node_modules from the build stage
COPY --from=build /app .

# Set the entry point and default command
ENTRYPOINT ["node", "/app/render-file.js"]
CMD ["--help"]

To create the Docker image, run the following command in the directory containing the Dockerfile:

docker build -t groupdocs-viewer-sample:latest .

In this example we mount the work directory and use it both to pass source files into the container and to store the rendered output.

If you do not have a license file, you can use the following command that omits the last parameter. GroupDocs.Viewer will work in trial mode.

docker run --rm -v "${pwd}/work:/work" -w /work groupdocs-viewer-sample:latest sample.pdf 

You can add a license parameter if you have a trial or full license file:

docker run --rm -v "${pwd}/work:/work" -w /work groupdocs-viewer-sample:latest sample.pdf work GroupDocs.Viewer.lic

• --rm: Automatically removes the container when it exits
• -v: Mounts the host directory to the container directory for file output
• -w: Sets the working directory inside container

The app renders a PDF file and outputs HTML files in the work folder. The output contains rendered pages in HTML format.

If you encounter missing glyphs or layout differences, install additional fonts:

RUN apt-get update && apt-get install -y fonts-liberation fonts-dejavu-core && rm -rf /var/lib/apt/lists/*

• Ensure build-essential and python3 are installed.
• Rebuild if needed: npm rebuild.

• Confirm OpenJDK is installed and JAVA_HOME/PATH are set in the image.

• Verify the mounted directories exist and are writable by the container user.

For general setup details, see System Requirements and Installation.