About Domino
Domino Data LabKnowledge BaseData Science BlogTraining

Add, modify, and share file handlers

Note

What is a file handler?

When you run a Job, Domino automatically handles the execution of the file. To do that, Domino already has the list of commands to be run based on the file extension. See Supported file types for the list of commands.

To execute a file extension that is not in the list, or to run a different command for a file extension that is in the list, you can use a file handler.

A file handler is a bash script with the name of the file extension (without the .sh extension), located in /opt/domino/handlers/{extension}.

File handler examples

  • The file handler /opt/domino/handlers/jpeg targets files with the .jpeg extension.

  • The file handler /opt/domino/handlers/py overrides the default behavior for .py files.

The file handler lives in the Environment’s file system, so the execution of the Job depends on the Environment in which you run the Job.

Tip

Add a file handler through the Domino UI

To add a file handler through the Domino UI, you must edit an Environment definition.

  1. Click Environments in the Domino sidebar.

  2. In the Dockerfile instructions field, create a directory for the custom file handler:

    RUN mkdir -p /opt/domino/bin/file-handlers

  3. Add the commands you want to execute when you invoke the file. Save the custom commands to a file with the same name as the file extension you want to target:

    RUN echo "#\!/bin/bash" >> /opt/domino/bin/file-handlers/<target-file-extension>
RUN echo "<Line 1 of bash script>" >> /opt/domino/bin/file-handlers/<target-file-extension>
RUN echo "<Line 2 of bash script>" >> /opt/domino/bin/file-handlers/<target-file-extension>
...

Add a file handler through the terminal

To add a file handler through the terminal, you must build a Docker image and upload it to an external repository. You can use the Docker image to create an Environment that contains your file handler.

  1. Create a directory for the custom file handler:

    mkdir -p /opt/domino/bin/file-handlers

  2. Add the commands you want to execute when you invoke the file. Save the custom commands to a file with the same name as the file extension you want to target:

    RUN echo "#\!/bin/bash" >> /opt/domino/bin/file-handlers/<target-file-extension>
RUN echo "<Line 1 of bash script>" >> /opt/domino/bin/file-handlers/<target-file-extension>
RUN echo "<Line 2 of bash script>" >> /opt/domino/bin/file-handlers/<target-file-extension>
...

  3. Save a copy of this file to a Docker image:

    FROM {DOCKER_BASE_IMAGE}
RUN mkdir -p /opt/domino/bin/file-handlers
COPY <target-file-extension> /opt/domino/bin/file-handlers/

  4. Build the Docker image and upload it to an external repository associated with your project.

    docker build -t "repository/domino-env-with-executable-target" .
docker push "repository/domino-env-with-executable-target"

Share a custom file handler

When you add custom file handlers to an Environment, the file handlers are associated with that Environment’s Docker image. Each Environment has its own Docker image. You can only have one Docker image per Environment.

If you must use your custom file handler in another Environment, you have several alternatives:

  1. If the file handler is in the Dockerfile instructions field, you can copy and paste the handler’s commands into the same field in a different Environment.

  2. If the file handler is in a Docker image in an external repository:

    1. Use the Docker image as a base to build Docker images for any Environment that needs your custom file handler.

    2. Upload the file handler itself to an external repository. You can reference this file from multiple Docker images.