myhtml2pdf Project

This project provides a REST API for processing PDF files, offering two main endpoints: /html2pdf and /merge. It acts as a wrapper for two powerful command-line utilities: wkhtmltopdf for converting HTML to PDF, and pdftk for merging PDF documents.

The primary goal is to offer a minimalist and straightforward implementation for specific use cases, but the codebase can be easily adapted for more generic purposes.

Features

• /html2pdf: Converts an HTML file (along with its assets like images and CSS) into a PDF.
• /merge: Merges multiple PDF files into a single document, sorted alphabetically by filename.

Both endpoints expect a .zip file containing all the necessary input files.

Prerequisites

Before you begin, ensure you have the following installed on your system:

• Go: Version 1.18 or higher.
• wkhtmltopdf: A command-line tool to render HTML into PDF.
• pdftk: A command-line tool for manipulating PDF documents.

Getting Started

Below are the instructions to get the project up and running on different platforms.

Windows (10 & 11)

1. Install Dependencies:

   • Download and install wkhtmltopdf from the official site.
   • Download and install pdftk from the official site.
   • Ensure the installation directories for both tools are added to your system's PATH environment variable.

2. Build the Application: Open a command prompt or PowerShell and run the following command from the project root to build the executable:

   go build -o mypdfservice.exe ./cmd/webapi/main.go

3. Run the Service: Execute the compiled binary:

   ./mypdfservice.exe

   The server will start listening on the default port 8080. To use a different port, pass it as an argument:

   ./mypdfservice.exe 9999

Linux (Debian/Ubuntu & openSUSE)

1. Install Dependencies:

   • For Debian/Ubuntu:

     sudo apt-get update
     sudo apt-get install -y wkhtmltopdf pdftk

   • For openSUSE:

     sudo zypper refresh
     sudo zypper install -y wkhtmltopdf pdftk

2. Build the Application: Open a terminal and run the following command from the project root:

   go build -o mypdfservice ./cmd/webapi/main.go

3. Run the Service: Execute the compiled binary:

   ./mypdfservice

   The server will start on port 8080. To specify a different port:

   ./mypdfservice 9999

Docker

A docker-compose setup is provided for easy local deployment.

1. Prerequisite: Ensure you have Docker and Docker Compose installed.

2. Build and Run: Navigate to the cmd/docker directory and run:

   cd cmd/docker
   docker-compose up --build

   This command will build the Docker image and start the service. The API will be accessible at http://localhost:8080.

Google Cloud Run

You can deploy the application as a serverless container to Google Cloud Run.

1. Prerequisites:

   • Install the Google Cloud CLI.
   • Authenticate and configure the CLI with your GCP project: gcloud auth login and gcloud config set project YOUR_PROJECT_ID.
   • Enable the Cloud Build and Cloud Run APIs for your project.

2. Deploy: From the project root directory, run the following command:

   gcloud builds submit --config cloudbuild.yaml .

   This command uses Cloud Build to build the container image, push it to the Google Container Registry, and deploy it as a new service on Cloud Run.

API Usage

/html2pdf Endpoint

• Method: POST
• Description: Converts an HTML file to a PDF.
• Input: A multipart/form-data request containing a single .zip file. The zip file must include:
  • One .html file.
  • All image files (.jpg, .jpeg, .png, .gif) referenced by <img> tags in the HTML. Image paths in the src attribute must match the filenames in the zip archive.

/merge Endpoint

• Method: POST
• Description: Merges multiple PDF files into one.
• Input: A multipart/form-data request containing a single .zip file with all the .pdf files to be merged. The files will be merged in alphabetical order of their filenames.

Testing with cURL

Here are examples of how to test the endpoints using cURL.

• Merge PDFs:

  curl -X POST http://localhost:8080/merge \
    -F "files=@/path/to/your/merge-example.zip" \
    -H "Content-Type: multipart/form-data" \
    -o merged_output.pdf

• Convert HTML to PDF:

  curl -X POST http://localhost:8080/html2pdf \
    -F "files=@/path/to/your/html-example.zip" \
    -H "Content-Type: multipart/form-data" \
    -o converted_output.pdf

Logging

The application maintains a detailed debug log in mypdfservice_debug.log, created in the same directory as the executable. This log is rotated automatically to manage disk space:

• The log file is limited to 10 MB.
• When the limit is reached, the file is compressed (e.g., mypdfservice_debug-TIMESTAMP.log.gz).
• A maximum of 20 old log files are kept.
• Logs older than 90 days are automatically deleted.

You can also capture a summary log of console output by redirecting the standard output:

# Windows
./mypdfservice.exe > summary.log

# Linux
./mypdfservice > summary.log

Acknowledgements

• Many thanks to the developers of the wkhtmltopdf and pdftk projects. This application would not be possible without their excellent work.
• This project was developed entirely using the Gitpod cloud development environment.

License

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