Viash 0.5.0

We’re proud to announce that we have released Viash 0.5.0. This new version has some improvements to the way components with a Docker backend can be ran and the Nextflow platform has some argument changes.

New Release

Viash Team


July 12, 2021

Viash 0.5.0 has some improvements to the way components with a Docker backend can be ran and the Nextflow platform has some argument changes.

Improvements to Docker backend

In the past, you needed to perform --setup on your Docker-based components and executables in order for the image to be built before you could run the component or executable. Now you can simply run your component or executable and Viash will do the image building automatically by default if it detects an image isn’t present yet. This behaviour can be changed by using a Docker setup strategy. For example:

viash build config.vsh.yaml -p docker --setup alwayscachedbuild

Nextflow gets some argument changes

Arguments for the Nextflow platform now have optional required and default values, just like their native and Docker counterparts. For example:

    - name: --name
      type: string
      description: Input name
      required: true
    - name: --repeat
      type: integer
      description: Times to repeat the name
      default: 100

Take a look at the Functionality page for more information on arguments and their properties.
As long as you use long-option arguments (e.g. --my-option) in the config file for required arguments, the way of specifying argument values for the Nextflow platform is identical to the Docker platform. You still access non-required arguments via this syntax: --<component_name>__<argument_name> <value>. For example:

my_component -- --my_component__input Hello!

Verbosity levels for viash run

Executables now have 8 levels of verbosity:

  1. emergency
  2. alert
  3. critical
  4. error
  5. warning
  6. notice
  7. info
  8. debug

The default verbosity level is notice. You can pass the -v or --verbose option to bump up the verbosity by one level. By passing -vv the verbosity goes up by two levels. You can manually set the verbosity by using the --verbosity <int_level> option. For example, if you wanted to only show errors or worse:

viash run config.vsh.yaml -- --verbosity 3

Full changelog:


  • DockerPlatform: A Docker setup will be performed by default. Default strategy has been changed to ifneedbepullelsecachedbuild (#57). ---setup strategy has been removed and ---docker_setup_strategy has been renamed to ---setup. This change allows running a component for the first time. During first time setup, the Docker container will be pulled or built automatically.

  • NativePlatform: Deprecated the native setup field.


  • NXF: This version changes the handling logic for arguments. An argument can be either required or not and can have a default: ... value or not. Checks are implemented to verify that required arguments are effectively provided during pipeline running.

  • NXF: If one sticks to long-option argments in the viash config, for all arguments that are required, the way of specifying the arguments on the CLI is identical for the Docker and NextFlow platforms. Non-required arguments can still be accessed from CLI using --<component_name>__<argument_name> ....

  • NXF: Running a module as a standalone pipeline has become easier.

  • viash run: Implement verbosity levels (#58). viash executables now have 7 levels of verbosity: emergency, alert, critical, error, warning, notice, info, debug. The default verbosity level is ‘notice’. Passing -v or --verbose bumps up the verbosity level by one, -vv by two. The verbosity level can be set manually by passing --verbosity x.


  • Docker Platform: Added privileged argument, allowing to run docker with the --privileged flag.

  • Docker Requirements: Allow specifying environment variables in the Dockerfile.

  • Config modding: Added a +0= operator to prepend items to a list.

  • viash run: Added a --version flag to viash executables for viewing the version of the component.

  • Functionality: Added checks on the functionality and argument names.

  • viash run: Added examples to functionality and arguments. Reworked --help formatting to include more information and be more consistent (#56).


  • Docker R Requirements: Install remotes when using { type: r, packages: [ foo ] }.

  • config: Throw error when user made a typo in the viash config (#62).


  • NXF: Add an end-to-end test for running a nextflow pipeline using viash components.

  • Docker: Reorganized viash docker build testbench into a main testbench with smaller auxiliary testbenches to keep them more manageable and clear what happens where.

  • viash ns: Added a basic testbench for namespace tests.