OCRmyPDF Docker image¶
OCRmyPDF is also available in a Docker image that packages recent versions of all dependencies.
For users who already have Docker installed this may be an easy and convenient option. However, it is less performant than a system installation and may require Docker engine configuration.
OCRmyPDF needs a generous amount of RAM, CPU cores, temporary storage space, whether running in a Docker container or on its own. It may be necessary to ensure the container is provisioned with additional resources.
Installing the Docker image¶
If you have Docker installed on your system, you can install a Docker image of the latest release.
If you can run this command successfully, your system is ready to download and execute the image:
docker run hello-world
The recommended OCRmyPDF Docker image is currently named
docker pull jbarlow83/ocrmypdf
OCRmyPDF will use all available CPU cores. By default, the VirtualBox machine instance on Windows and macOS has only a single CPU core enabled. Use the VirtualBox Manager to determine the name of your Docker engine host, and then follow these optional steps to enable multiple CPUs:
# Optional step for Mac OS X users docker-machine stop "yourVM" VBoxManage modifyvm "yourVM" --cpus 2 # or whatever number of core is desired docker-machine start "yourVM" eval $(docker-machine env "yourVM")
See the Docker documentation for adjusting memory and CPU on other platforms.
Using the Docker image on the command line¶
Unlike typical Docker containers, in this section the OCRmyPDF Docker container is emphemeral – it runs for one OCR job and terminates, just like a command line program. We are using Docker to deliver an application (as opposed to the more conventional case, where a Docker container runs as a server).
To start a Docker container (instance of the image):
docker tag jbarlow83/ocrmypdf ocrmypdf docker run --rm -i ocrmypdf (... all other arguments here...) - -
For convenience, create a shell alias to hide the Docker command. It is easier to send the input file as stdin and read the output from stdout – this avoids the messy permission issues with Docker entirely.
alias docker_ocrmypdf='docker run --rm -i ocrmypdf' docker_ocrmypdf --version # runs docker version docker_ocrmypdf - - <input.pdf >output.pdf
Or in the wonderful fish shell:
alias docker_ocrmypdf 'docker run --rm ocrmypdf' funcsave docker_ocrmypdf
Alternately, you could mount the local current working directory as a Docker volume:
alias docker_ocrmypdf='docker run --rm -i --user "$(id -u):$(id -g)" --workdir /data -v "$PWD:/data" ocrmypdf' docker_ocrmypdf /data/input.pdf /data/output.pdf
Adding languages to the Docker image¶
By default the Docker image includes English, German, Simplified Chinese, French, Portuguese and Spanish, the most popular languages for OCRmyPDF users based on feedback. You may add other languages by creating a new Dockerfile based on the public one:
FROM jbarlow83/ocrmypdf # Add French RUN apt install tesseract-ocr-fra
You can also copy training data to
Executing the test suite¶
The OCRmyPDF test suite is installed with image. To run it:
docker run --entrypoint python3 jbarlow83/ocrmypdf -m pytest
Accessing the shell¶
To use the bash shell in the Docker image:
docker run -it --entrypoint bash jbarlow83/ocrmypdf
Using the OCRmyPDF web service wrapper¶
The OCRmyPDF Docker image includes an example, barebones HTTP web service. The webservice may be launched as follows:
docker run --entrypoint python3 -p 5000:5000 jbarlow83/ocrmypdf webservice.py
This will configure the machine to listen on port 5000. On Linux machines
this is port 5000 of localhost. On macOS or Windows machines running
Docker, this is port 5000 of the virtual machine that runs your Docker
images. You can find its IP address using the command
Unlike command line usage this program will open a socket and wait for connections.
The OCRmyPDF web service wrapper is intended for demonstration or development. It provides no security, no authentication, no protection against denial of service attacks, and no load balancing. The default Flask WSGI server is used, which is intended for development only. The server is single-threaded and so can respond to only one client at a time. While running OCR, it cannot respond to any other clients.
Clients must keep their open connection while waiting for OCR to complete. This may entail setting a long timeout; this interface is more useful for internal HTTP API calls.
Unlike the rest of OCRmyPDF, this web service is licensed under the Affero GPLv3 (AGPLv3) since Ghostscript is also licensed in this way.
In addition to the above, please read our general remarks on using OCRmyPDF as a service.