Viash 0.2.0

Posted September 1, 2020 by Viash Team ‐ 4 min read

Version attribute added, automatic resolving of Docker paths, ...

Changes to functionality metadata

  • Added version attribute

Autoresolve docker paths

Arguments of type: file are processed to automatically create a mount in docker. More specifically, when you pass an argument value: --input /path/to/file, this will be processed such that the following parameters are passed to docker:

docker run -v /path/to:/viash_automount/path/to ... --input /viash_automount/path/to/file

If, for some reason, you need to manually specify a mount, you can do this with ---mount /path/to/mount:/mymount.

Argument multiplicity

For all parameter types (except for boolean_true and boolean_false), you can specify multiple: true in order to turn this argument into an array-based argument. What this does is allow you to pass multiple values for this argument, e.g. --input file1 --input file2 --input file3:file4:file5.

The default separator is : but this can be overridden by changing the separator by setting it to multiple_sep: "," (for example).

New format

Viash now supports placing the functionality.yaml, platform*.yaml(s) and script into a single file. For example, this could be a merged script.R:

#' functionality:
#'   name: r-estimate
#'   arguments: ...
#' platforms:
#' - type: native
#' - type: docker
#'   image: rocker/tidyverse
cat("Hello world!\n")

Instead of running:

viash run -f functionality.yaml -p platform_docker.yaml -- arg1

With this format, you can now run:

viash run script.R                     # run script.R with the first platform
viash run -P docker script.R           # run script.R with the platform called 'docker' with the large P argument
# use small p to override the platform with a custom yaml:
viash run -p ../common_resources/platform_docker.yaml script.R
# note that any arguments for the run command (e.g. -p or -P) should come before the script.R, as script.R is considered a trailing argument.

Full changelog:


  • Allow (optional) version attributes in functionality.yaml and platform.yaml.
  • Allow testing a component with the viash test functionality. Tests are executed in a temporary directory on the specified platform. The temporary directory contains all the resource and test files.
  • viash --version: Add flag for printing the version of viash.
  • Allow fetching resources from URL (http:// and https://)
  • Allow retrieving functionality and platform YAMLs from URL.
  • For docker containers, autoresolve path names of files. Use ---v path:path or ---volume path:path to manually mount a specific folder.
  • Implement parameter multiplicity. Set multiple: true to denote an argument to have higher multiplicity. Run ./cmd --foo one --foo two --foo three:four in order for multiple values to be added to the same parameter list.
  • Added a new format for defining functionality in which the user passes the script in which the functionality and platforms are listed as yaml headers.
  • ---chown flag has been added to Docker executables to automatically change the ownership of output files to the current user.
  • viash ns build: A command for building a whole namespace.
  • NXF: Join operations are now fully supported by means of multiple.
  • NXF: Modules that perform joins can take either arrays (multiple input files or the same type to be joined) or hashes (multiple input files passed using different options on the CLI). Please refer to the docs for more info.


  • Remove passthrough parameters.
  • Since CLI generation is now performed in the outer script, viash pimp has been deprecated.
  • Write out meta.yaml containing viash run information as well as the original functionality.yaml and platform.yaml content.
  • Renamed viash export to viash build.


  • viash run and viash test: Allow changing the temporary directory by defining VIASH_TEMP as a environment variable. Temporary directories are cleaned up after successful executions.
  • viash run and viash test: Exit(1) when execution or test fails.
  • viash build: Add -m flag for outputting metadata after build.
  • viash run: Required parameters can have a default value now. Produce error when a required parameter is not passed, even when a default is provided.
  • NXFModules are now stored under target/nextflow by default


  • NXF: Correctly escape path variable when running NXF command.
  • NXF: Surround parameters with quotes when running NXF command.


  • Move CLI from inner script to outer script.
  • Renamed Target to Platform
  • Renamed Environment to Requirements