Viash

https://viash.io/
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### Start Docker Service (if needed)

Source: https://viash.io/installation

Starts the Docker daemon service if it is not already running. This is often necessary on Linux systems before running Docker commands.

```shell
sudo systemctl start docker --now
```

--------------------------------

### Configure Docker Engine with Image and Apt Setup

Source: https://viash.io/reference/config/engines/docker

This example shows how to configure the Docker engine with a base image and specifies apt packages to be installed during setup. This is useful for ensuring necessary tools like 'curl' are available in the Docker environment.

```yaml
engines:
  - type: docker
    image: "bash:4.0"
    setup:
      - type: apt
        packages: [ curl ]
```

--------------------------------

### Test Docker Installation via WSL2

Source: https://viash.io/installation

Runs a 'hello-world' container to verify that Docker is installed and functioning correctly within the WSL2 environment.

```shell
docker run hello-world
```

--------------------------------

### Install Viash using wget

Source: https://viash.io/installation

Downloads and executes the Viash installation script using wget. This method installs Viash to a directory on the system's PATH.

```shell
wget -qO- dl.viash.io | bash
sudo mv viash /usr/local/bin
```

--------------------------------

### Verify Viash Installation

Source: https://viash.io/installation

Checks if Viash has been installed correctly by displaying its help information. This command should be run after installation to confirm it's accessible.

```shell
viash --help
```

--------------------------------

### Install Viash using curl

Source: https://viash.io/installation

Downloads and executes the Viash installation script using curl. This method installs Viash to the current working directory.

```shell
curl -fsSL dl.viash.io | bash
mv viash $HOME/bin/viash
```

--------------------------------

### Build Docker Image Notification

Source: https://viash.io/guide/component/add-dependencies

Example log message indicating the start of building a container image for a Viash component.

```text
[notice] Building container 'example_bash_with_setup:latest' with Dockerfile
```

--------------------------------

### Viash Docker Engine: Ruby Dependencies with GitHub

Source: https://viash.io/guide/component/add-dependencies

Example of specifying Ruby package dependencies and GitHub repositories for installation within a Viash Docker engine setup.

```yaml
setup:
  - type: ruby
    packages: [ pry ]
    github: [ "pry/pry" ]
```

--------------------------------

### Viash Docker Engine: Ruby Dependencies

Source: https://viash.io/guide/component/add-dependencies

Example of specifying Ruby package dependencies for installation within a Viash Docker engine setup.

```yaml
setup:
  - type: ruby
    packages: [ pry ]
```

--------------------------------

### Viash Placeholder Code Block Examples

Source: https://viash.io/reference/viash_code_block

Demonstrates the Viash placeholder code block structure for various programming languages, showing how user-defined parameters are declared within the VIASH START and VIASH END comments.

```Bash
#!/bin/bash

## VIASH START
par_input=path/to/file.txt
par_output=output.txt
## VIASH END

# copy file
echo "Copying '$par_input' to '$par_output'."
cp -r "$par_input" "$par_output"
```

```C#
using System.IO;

// VIASH START
var par = new {
  input = "path/to/file.txt",
  output = "output.txt"
};
// VIASH END

// copy file
Console.WriteLine($"Copying '{par.input}' to '{par.output}'.");
File.Copy(par.input, par.output, true);
```

```JavaScript
const fs = require('fs');

// VIASH START
let par = {
  'input': 'path/to/file.txt',
  'output': 'output.txt'
};
// VIASH END

// copy file
console.log(`Copying '${par['input']}' to '${par['output']}'`)
fs.copyFile(par['input'], par['output'], (err) => {
  if (err) throw err;
});
```

```Python
import shutil

## VIASH START
par = {
  'input': 'file.txt',
  'output': 'output.txt'
}
## VIASH END

# copy file
print(f"Copying '{par['input']}' to '{par['output']}'.")
shutil.copyfile(par['input'], par['output'])
```

```R
## VIASH START
par <- list(
  "input" = 'file.txt',
  "output" = 'output.txt'
)
## VIASH END

# copy file
cat("Copying '", par$input, "' to '", par$output, "'.\n", sep = "")
file.copy(par$input, par$output)
```

```Scala
import java.nio.file.StandardCopyOption.REPLACE_EXISTING
import java.nio.file.Files
import java.nio.file.Paths

// VIASH START
case class ViashPar(input: String, output: String)
val par = ViashPar(
  "path/to/file.txt",
  "output.txt"
)
// VIASH END

// copy file
println(s"Copying '${par.input}' to '${par.output}'.")
val fileIn = Paths.get(par.input)
val fileOut = Paths.get(par.output)
Files.copy(fileIn, fileOut, REPLACE_EXISTING)
```

--------------------------------

### Build Docker Image Command (C#)

Source: https://viash.io/guide/component/add-dependencies

Command to build the Docker image for the 'example_csharp_with_setup' component, using the '--setup cachedbuild' flag.

```bash
target/example_csharp_with_setup ---setup cachedbuild
```

--------------------------------

### Build Docker Image Command (R)

Source: https://viash.io/guide/component/add-dependencies

Command to build the Docker image for the 'example_r_with_setup' component, using the '--setup cachedbuild' flag.

```bash
target/example_r_with_setup ---setup cachedbuild
```

--------------------------------

### Running VIASH Component (Bash Example)

Source: https://viash.io/guide/component/add-resources

Example command to run a VIASH component using Bash. This command executes a configuration file and specifies input and output parameters.

```bash
viash run config.vsh.yaml -- --input config.vsh.yaml --output foo.txt
```

--------------------------------

### Viash Docker Engine: Javascript Dependencies

Source: https://viash.io/guide/component/add-dependencies

Example of specifying Javascript package dependencies and optionally GitHub repositories for installation within a Viash Docker engine setup.

```yaml
setup:
  - type: javascript
    packages: [ express ]
    github: [ "expressjs/express" ]
```

--------------------------------

### Build Docker Image Command (JavaScript)

Source: https://viash.io/guide/component/add-dependencies

Command to build the Docker image for the 'example_js_with_setup' component, using the '--setup cachedbuild' flag.

```bash
target/example_js_with_setup ---setup cachedbuild
```

--------------------------------

### Viash Package Configuration Example

Source: https://viash.io/reference/packageConfig

Example of a _viash.yaml file demonstrating basic package configuration, including version, source, target, organization, and custom config modifications.

```yaml
viash_version: 0.9.0
source: src
target: target
version: 1.0
organization: viash-io
links:
  repository: 'https://github.com/viash-io/viash'
  docker_registry: 'ghcr.io'
config_mods: |
  .runners[.type == 'nextflow'].directives.tag := '$id'
  .runners[.type == 'nextflow'].config.script := 'includeConfig("configs/custom.config")'
```

--------------------------------

### Build Docker Image Command (Python)

Source: https://viash.io/guide/component/add-dependencies

Command to build the Docker image for the 'example_python_with_setup' component, using the '--setup cachedbuild' flag.

```bash
target/example_python_with_setup ---setup cachedbuild
```

--------------------------------

### Configure Docker Platform Base Image and Setup

Source: https://viash.io/reference/config/deprecated/platforms/docker

Defines a Docker platform for Viash components, specifying the base Docker image and the setup instructions for installing dependencies within the container. This allows for reproducible builds or pulling pre-built images.

```yaml
platforms:
  - type: docker
    image: "bash:4.0"
    setup:
      - type: apt
        packages: [ curl ]
```

--------------------------------

### Nextflow Platform Configuration Example

Source: https://viash.io/reference/config/deprecated/platforms/nextflow

Example of how to configure the Nextflow platform, specifying its type and associated directives like labels for resource allocation.

```yaml
platforms:
  - type: nextflow
    directives:
      label: [lowcpu, midmem]
```

--------------------------------

### Check Java Installation

Source: https://viash.io/installation

Verifies if Java is installed on the system. This is a prerequisite for Viash as it is developed in Scala.

```shell
java -version
```

--------------------------------

### Viash Docker Engine: Python Dependencies

Source: https://viash.io/guide/component/add-dependencies

Example of specifying Python package dependencies and optionally GitHub repositories for installation within a Viash Docker engine setup.

```yaml
setup:
  - type: python
    packages: [ anndata ]
  github: [ jkbr/httpie ]
```

--------------------------------

### Viash Docker Engine: Apt Dependencies

Source: https://viash.io/guide/component/add-dependencies

Example of specifying package dependencies to be installed using the 'apt' package manager within a Viash Docker engine setup.

```yaml
setup:
  - type: apt
    packages: [ curl ]
```

--------------------------------

### Install Python Packages from Generic URL

Source: https://viash.io/reference/config/engines/docker/setup/pythonRequirements

Installs Python packages from a generic URL, typically a zipball or tarball of the package source. The `setup` block also demonstrates this.

```yaml
url: [ https://github.com/some_org/some_pkg/zipball/master ]
```

--------------------------------

### Execute C# Component

Source: https://viash.io/guide/component/create-component

Example of executing a C# component named 'example_csharp'. Similar to the Bash example, it requires '--input' and '--output' parameters. The log output details the Docker image availability check, potential pull failures, and the container build process.

```csharp
viash run config.vsh.yaml -- --input config.vsh.yaml --output foo.txt
```

```text
[notice] Checking if Docker image is available at 'example_csharp:latest'
[warning] Could not pull from 'example_csharp:latest'. Docker image doesn't exist or is not accessible.
[notice] Building container 'example_csharp:latest' with Dockerfile
Copying '/viash_automount/tmp/Rtmp7GQqUa/create_new_component8d4e13c7eb41/csharp/config.vsh.yaml' to '/viash_automount/tmp/Rtmp7GQqUa/create_new_component8d4e13c7eb41/csharp/foo.txt'.
```

--------------------------------

### Build Docker Image Command (Bash)

Source: https://viash.io/guide/component/add-dependencies

Command to build the Docker image for the 'example_bash_with_setup' component, using the '--setup cachedbuild' flag.

```bash
target/example_bash_with_setup ---setup cachedbuild
```

--------------------------------

### R Unit Test Setup for Viash Component

Source: https://viash.io/guide/component/unit-testing

This R code snippet shows the setup for a unit test of a Viash component. It defines the meta information, which includes the executable path for the R component. Further testing logic would follow this setup.

```r
## VIASH START
meta <- list(
  "target/example_r"
)

```

--------------------------------

### Nextflow Example Directives

Source: https://viash.io/reference/config/runners/nextflow/directives

A basic example of Nextflow directives specifying container, label, CPU, and memory requirements for a process.

```yaml
directives:
    container: rocker/r-ver:4.1
    label: highcpu
    cpus: 4
    memory: 16 GB
```

--------------------------------

### Configure Executable Runner with Port

Source: https://viash.io/reference/config/runners/executable

Example configuration for the executable runner, specifying the runner type and the port to be exposed. This is a basic setup for running code as an executable.

```yaml
runners:
  - type: executable
    port: 8080
```

--------------------------------

### Example Summary Configuration

Source: https://viash.io/reference/config

Illustrates how to set a one-sentence summary for a Viash component, used in documentation generation.

```yaml
summary: "A component for performing XYZ"
```

--------------------------------

### Update and Upgrade Ubuntu Packages via WSL2

Source: https://viash.io/installation

Updates the package list and upgrades all installed packages on Ubuntu running within WSL2. This ensures the system is up-to-date before further installations.

```shell
sudo apt-get update && sudo apt-get upgrade -y
```

--------------------------------

### Install Homebrew and Java 17 on macOS

Source: https://viash.io/installation

Installs Homebrew package manager and then OpenJDK 17 on macOS. Homebrew simplifies the installation of software on macOS.

```shell
/bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh)"
brew install openjdk@17
```

--------------------------------

### Install R Packages from Generic URL

Source: https://viash.io/reference/config/engines/docker/setup/rRequirements

Installs R packages from a generic URL, which can point to zip archives or other package distributions. Useful for installing specific versions or packages not hosted on standard repositories.

```yaml
url: [ https://github.com/hadley/stringr/archive/HEAD.zip ]
```

--------------------------------

### Install R Packages from Bitbucket

Source: https://viash.io/reference/config/engines/docker/setup/rRequirements

Installs R packages from Bitbucket repositories. Accepts package names in 'user/repo' format or full Git URIs.

```yaml
bitbucket: [ org/package ]
```

--------------------------------

### Install R Packages from GitHub

Source: https://viash.io/reference/config/engines/docker/setup/rRequirements

Installs R packages directly from GitHub repositories. Accepts package names in 'user/repo' format or full Git URIs. Useful for development versions or private repositories.

```yaml
github: [ rcannood/SCORPIUS ]
```

--------------------------------

### Specify Target Image Name for Setup

Source: https://viash.io/reference/config/engines/docker

Configures a specific name ('myfoo') for the Docker image that will be built when setup instructions are provided. If no setup is defined, the 'image' field is used.

```yaml
target_image: myfoo
```

--------------------------------

### Install R Packages from GitLab

Source: https://viash.io/reference/config/engines/docker/setup/rRequirements

Installs R packages from GitLab repositories. Similar to GitHub, it accepts 'user/repo' format or full Git URIs.

```yaml
gitlab: [ org/package ]
```

--------------------------------

### View Dockerfile for JavaScript Component

Source: https://viash.io/guide/component/add-dependencies

Displays the Dockerfile for the JavaScript component. It uses a Node.js slim image and installs curl and wget.

```Bash
target/example_js_with_setup ---dockerfile
```

```Dockerfile
FROM node:19-bullseye-slim
ENTRYPOINT []
RUN apt-get update && \
  DEBIAN_FRONTEND=noninteractive apt-get install -y curl wget && \
  rm -rf /var/lib/apt/lists/*

LABEL org.opencontainers.image.description="Companion container for running component example_js_with_setup"
LABEL org.opencontainers.image.created="2025-10-10T13:50:31Z"
```

--------------------------------

### C# Docker Image with Setup

Source: https://viash.io/guide/component/add-dependencies

Defines a Viash component using a C# script, extending a .NET Docker image with 'curl' and 'wget' via package manager setup. Supports native and Docker engines, with executable and Nextflow runners.

```yaml
name: example_csharp_with_setup
description: A minimal example component.
arguments:
  - type: file
    name: --input
    example: file.txt
    required: true
  - type: file
    name: --output
    direction: output
    example: output.txt
    required: true
resources:
  - type: csharp_script
    path: script.csx
engines:
  - type: docker
    image: ghcr.io/data-intuitive/dotnet-script:1.3.1
    setup:
      - type: apk
        packages:
          - curl
          - wget
  - type: native
runners:
  - type: executable
  - type: nextflow
```

--------------------------------

### View Dockerfile for Scala Component

Source: https://viash.io/guide/component/add-dependencies

Displays the Dockerfile for the Scala component. It uses an sbt-based Scala image and installs curl and wget.

```Bash
target/example_scala_with_setup ---dockerfile
```

```Dockerfile
FROM sbtscala/scala-sbt:eclipse-temurin-19_36_1.7.2_2.13.10
ENTRYPOINT []
RUN apt-get update && \
  DEBIAN_FRONTEND=noninteractive apt-get install -y curl wget && \
  rm -rf /var/lib/apt/lists/*

LABEL org.opencontainers.image.description="Companion container for running component example_scala_with_setup"
LABEL org.opencontainers.image.created="2025-10-10T13:51:53Z"
```

--------------------------------

### Specify Apt Packages in Viash IO Setup

Source: https://viash.io/reference/config/engines/docker/setup/aptRequirements

This snippet demonstrates how to declare apt package requirements within the 'setup' section of a Viash IO component configuration. It specifies that the 'sl' package should be available. Dependencies include the Viash IO framework.

```yaml
setup:
  - type: apt
    packages: [ sl ]
```

--------------------------------

### String Argument with Example Value

Source: https://viash.io/reference/config/arguments/string

Specifies an example value for a string argument. This can serve as the default if no 'default' property is set.

```yaml
- name: --my_string
  type: string
  example: "Hello World"
```

--------------------------------

### YAML Example: Component References

Source: https://viash.io/reference/config/references

An example demonstrating how to define both DOI and BibTeX references for a component in YAML format. This is crucial for attribution and scientific reproducibility.

```yaml
references:
  doi: 10.1000/xx.123456.789
  bibtex: |
    @article{foo,
      title={Foo},
      author={Bar},
      journal={Baz},
      year={2024}
    }
```

--------------------------------

### VDSL3 Module Interface Example

Source: https://viash.io/reference/nextflow_vdsl3/import_module

Illustrates the expected input and output channel interface for VDSL3 modules. The module takes a channel of [id, state] tuples and emits a channel of [id, new_state] tuples, where state is a Map.

```nextflow
workflow {
  Channel.fromList([
    ["myid", [input: file("in.txt")]]
  ])
    | mymodule
}

```

--------------------------------

### View Dockerfile for Python Component

Source: https://viash.io/guide/component/add-dependencies

Displays the Dockerfile for the Python component. It utilizes a slim Python image and installs anndata.

```Bash
target/example_python_with_setup ---dockerfile
```

```Dockerfile
FROM python:3.10-slim
ENTRYPOINT []
RUN apt-get update && \
  DEBIAN_FRONTEND=noninteractive apt-get install -y curl wget && \
  rm -rf /var/lib/apt/lists/*

RUN pip install --upgrade pip && \
  pip install --upgrade --no-cache-dir "anndata"

LABEL org.opencontainers.image.description="Companion container for running component example_python_with_setup"
LABEL org.opencontainers.image.created="2025-10-10T13:50:44Z"
```

--------------------------------

### Define a file argument with an example value

Source: https://viash.io/reference/config/arguments/file

Provides an example value for a file argument. If no default value is specified, this example value will be used as the default.

```yaml
- name: --my_file
  type: file
  example: data.csv
```

--------------------------------

### Git Repository URI Example (YAML)

Source: https://viash.io/reference/config/repositories/gitRepository

An example demonstrating the format for specifying the Uniform Resource Identifier (URI) of a Git repository. This URI is used to locate the remote repository where dependency components are hosted.

```yaml
uri: "git+https://github.com/openpipelines-bio/openpipeline.git"
```

--------------------------------

### Scala Docker Image with Setup

Source: https://viash.io/guide/component/add-dependencies

Defines a Viash component using a Scala script, extending a Scala Docker image with 'curl' and 'wget' via package manager setup. Supports native and Docker engines, with executable and Nextflow runners.

```yaml
name: example_scala_with_setup
description: A minimal example component.
arguments:
  - type: file
    name: --input
    example: file.txt
    required: true
  - type: file
    name: --output
    direction: output
    example: output.txt
    required: true
resources:
  - type: scala_script
    path: script.scala
engines:
  - type: docker
    image: sbtscala/scala-sbt:eclipse-temurin-19_36_1.7.2_2.13.10
    setup:
      - type: apt
        packages:
          - curl
          - wget
  - type: native
runners:
  - type: executable
  - type: nextflow
```

--------------------------------

### Install JavaScript Packages from Generic URI

Source: https://viash.io/reference/config/engines/docker/setup/javascriptRequirements

This section details how to specify JavaScript packages to be installed from a generic Uniform Resource Identifier (URI), such as a zip archive. Provide the full URI for the package source. This can be a single URI or a list of URIs.

```yaml
url: [ https://github.com/org/repo/archive/HEAD.zip ]
```

--------------------------------

### Viash Version Output

Source: https://viash.io/guide/project/package-config

Example output showing the currently active Viash version after configuration.

```text
viash 0.9.0 (c) 2020 Data Intuitive

```

--------------------------------

### Install JavaScript Packages from GitHub

Source: https://viash.io/reference/config/engines/docker/setup/javascriptRequirements

This section details how to specify JavaScript packages to be installed directly from a GitHub repository. Provide the repository in the format 'owner/repository'. This can be a single repository or a list of repositories.

```yaml
github: [ owner/repository ]
```

--------------------------------

### Install JavaScript Packages from Git URI

Source: https://viash.io/reference/config/engines/docker/setup/javascriptRequirements

This section details how to specify JavaScript packages to be installed directly from a Git Uniform Resource Identifier (URI). Provide the full Git URI for the repository. This can be a single URI or a list of URIs.

```yaml
git: [ https://some.git.repository/org/repo ]
```

--------------------------------

### Bash Docker Image with Setup

Source: https://viash.io/guide/component/add-dependencies

Defines a Viash component using a Bash script, extending a Bash Docker image with 'curl' and 'wget' via package manager setup. Supports native and Docker engines, with executable and Nextflow runners.

```yaml
name: example_bash_with_setup
description: A minimal example component.
arguments:
  - type: file
    name: --input
    example: file.txt
    required: true
  - type: file
    name: --output
    direction: output
    example: output.txt
    required: true
resources:
  - type: bash_script
    path: script.sh
engines:
  - type: docker
    image: bash:4.0
    setup:
      - type: apk
        packages:
          - curl
          - wget
  - type: native
runners:
  - type: executable
  - type: nextflow
```

--------------------------------

### Docker Setup Strategy Configuration

Source: https://viash.io/reference/config/deprecated/platforms/docker

Configures the Docker setup strategy for building container images. Options range from always building, using cached builds, pulling from registries, or doing nothing. This setting determines how the Docker image is obtained or created.

```yaml
setup_strategy: alwaysbuild
```

--------------------------------

### Example Requirements Configuration (YAML)

Source: https://viash.io/reference/config/computationalRequirements

An example of how to specify computational requirements for a component in YAML format. This includes the number of CPUs and the amount of memory the component needs.

```yaml
requirements:
  cpus: 5
  memory: 10GB
```

--------------------------------

### Viash Docker Engine: Apk Dependencies

Source: https://viash.io/guide/component/add-dependencies

Example of specifying package dependencies to be installed using the 'apk' package manager within a Viash Docker engine setup.

```yaml
setup:
  - type: apk
    packages: [ curl ]
```

--------------------------------

### Docker Setup with Custom Commands

Source: https://viash.io/reference/config/engines/docker/setup/dockerRequirements

Defines a Docker setup step that executes custom shell commands during the build process. It allows specifying build arguments and multi-line commands to be run.

```yaml
setup:
  - type: docker
    build_args: "R_VERSION=hello_world"
    run: |
      echo 'Run a custom command'
      echo 'Foo' > /path/to/file.txt
```

--------------------------------

### View Dockerfile for R Component

Source: https://viash.io/guide/component/add-dependencies

Displays the Dockerfile for the R component. It uses an R2U base image and installs the tidyverse package.

```Bash
target/example_r_with_setup ---dockerfile
```

```Dockerfile
FROM eddelbuettel/r2u:22.04
ENTRYPOINT []
RUN apt-get update && \
  DEBIAN_FRONTEND=noninteractive apt-get install -y curl wget && \
  rm -rf /var/lib/apt/lists/*

RUN Rscript -e 'options(warn = 2); if (!requireNamespace("remotes", quietly = TRUE)) install.packages("remotes")' && \
  Rscript -e 'options(warn = 2); remotes::install_cran(c("tidyverse"), repos = "https://cran.rstudio.com")'

LABEL org.opencontainers.image.description="Companion container for running component example_r_with_setup"
LABEL org.opencontainers.image.created="2025-10-10T13:51:10Z"
```

--------------------------------

### Viash Docker Engine: R Dependencies

Source: https://viash.io/guide/component/add-dependencies

Example of specifying R package dependencies, Bioconductor packages, and GitHub repositories for installation within a Viash Docker engine setup.

```yaml
setup:
  - type: r
    packages: [ anndata ]
    bioc: [ AnnotationDbi, SingleCellExperiment ]
    github: rcannood/SCORPIUS
```

--------------------------------

### Nextflow Directives Configuration Example

Source: https://viash.io/reference/config/deprecated/platforms/nextflow

Shows how to set Nextflow directives for container image, CPU, memory, and labels to manage process execution.

```yaml
directives:
  container: rocker/r-ver:4.1
  label: highcpu
  cpus: 4
  memory: 16 GB
```

--------------------------------

### Execute Bash Component

Source: https://viash.io/guide/component/create-component

Example of executing a Bash component named 'example_bash'. It shows how to provide required file parameters like '--input' and '--output' to the component. The output log indicates the status of the Docker image check and build process.

```bash
viash run config.vsh.yaml -- --input config.vsh.yaml --output foo.txt
```

```text
[notice] Checking if Docker image is available at 'example_bash:latest'
[warning] Could not pull from 'example_bash:latest'. Docker image doesn't exist or is not accessible.
[notice] Building container 'example_bash:latest' with Dockerfile
Copying '/viash_automount/tmp/Rtmp7GQqUa/create_new_component8d4e13c7eb41/bash/config.vsh.yaml' to '/viash_automount/tmp/Rtmp7GQqUa/create_new_component8d4e13c7eb41/bash/foo.txt'.
```

--------------------------------

### Viash Package Description Configuration

Source: https://viash.io/reference/packageConfig

Example of how to provide a multiline description for a Viash package, used for documentation purposes.

```yaml
description: |
  A (multiline) description of the purpose of this package
  and the components it contains.
```

--------------------------------

### Run Viash Component with Help

Source: https://viash.io/guide/component/create-component

This command demonstrates how to access the help information for a Viash component, providing an overview of its parameters and descriptions. It's useful for understanding the expected inputs and outputs.

```bash
viash run config.vsh.yaml -- --help
```

--------------------------------

### Install Viash Dependencies on WSL2 Ubuntu

Source: https://viash.io/installation

Installs OpenJDK 17, unzip, and zip packages on Ubuntu within WSL2. These are essential dependencies for Viash.

```shell
sudo apt-get install -y openjdk-17-jdk unzip zip
```

--------------------------------

### Install Java 17 on RHEL/Fedora

Source: https://viash.io/installation

Installs OpenJDK 17, unzip, and curl on RHEL or Fedora systems using the yum package manager. These are required dependencies for Viash.

```shell
sudo yum install java-17-openjdk-devel unzip curl
```

--------------------------------

### Argument Group Summary Example (YAML)

Source: https://viash.io/reference/config/argumentGroup

This YAML snippet demonstrates how to provide a concise one-sentence summary for an argument group, used for documentation.

```yaml
summary: "Arguments related to functionality XYZ"
```

--------------------------------

### Filtering Components with Query

Source: https://viash.io/reference/cli/ns_exec

This example shows how to filter which Viash components the command is applied to using the `--query` option with a regular expression.

```shell
viash ns exec --query "^my_namespace/component_.*" --cmd 'echo Found component {path}'
```

--------------------------------

### Install Java 17 on Debian/Ubuntu

Source: https://viash.io/installation

Installs OpenJDK 17, unzip, and curl on Debian or Ubuntu systems using the apt package manager. These are required dependencies for Viash.

```shell
sudo apt-get update
sudo apt-get install openjdk-17-jdk unzip curl
```

--------------------------------

### Run R Executable with Input/Output

Source: https://viash.io/guide/component/create-component

Demonstrates running a Viash-generated R script by providing input and output file paths. This example shows the command-line invocation and the resulting output, including a confirmation message and file listing.

```r
target/example_r --input config.vsh.yaml --output output.txt
```

```text
Copying '/viash_automount/tmp/Rtmp7GQqUa/create_new_component8d4e13c7eb41/r/config.vsh.yaml' to '/viash_automount/tmp/Rtmp7GQqUa/create_new_component8d4e13c7eb41/r/output.txt'.
[1] TRUE
```

```text
ls -l
total 20
-rw-r--r-- 1 runner runner  418 Oct 10 13:47 config.vsh.yaml
-rw-r--r-- 1 runner runner  418 Oct 10 13:48 foo.txt
-rw-r--r-- 1 runner runner  418 Oct 10 13:49 output.txt
-rwxr-xr-x 1 runner runner  207 Oct 10 13:47 script.R
drwxr-xr-x 2 runner runner 4096 Oct 10 13:49 target
```

--------------------------------

### Run Scala Executable with Input/Output

Source: https://viash.io/guide/component/create-component

Shows how to execute a Viash-generated Scala script, requiring input and output file specifications. This example includes the command to run the script and the resulting file system information, noting any compilation warnings.

```scala
target/example_scala --input config.vsh.yaml --output output.txt
```

```text
warning: 1 deprecation; re-run with -deprecation for details
Copying '/viash_automount/tmp/Rtmp7GQqUa/create_new_component8d4e13c7eb41/scala/config.vsh.yaml' to '/viash_automount/tmp/Rtmp7GQqUa/create_new_component8d4e13c7eb41/scala/output.txt'.
```

```text
ls -l
total 20
-rw-r--r-- 1 runner runner  462 Oct 10 13:47 config.vsh.yaml
-rw-r--r-- 1 runner runner  462 Oct 10 13:48 foo.txt
-rw-r--r-- 1 runner runner  462 Oct 10 13:49 output.txt
-rw-r--r-- 1 runner runner  435 Oct 10 13:47 script.scala
drwxr-xr-x 2 runner runner 4096 Oct 10 13:49 target
```

--------------------------------

### Install Java 17 on Arch Linux

Source: https://viash.io/installation

Installs OpenJDK 17, unzip, and curl on Arch Linux systems using the pacman package manager. These are required dependencies for Viash.

```shell
sudo pacman -Syy jdk17-openjdk unzip curl
```

--------------------------------

### Viash `.run()`: State Management with `fromState` and `toState`

Source: https://viash.io/reference/nextflow_vdsl3/import_module

Illustrates how to manage component state using `fromState` and `toState` arguments in the `.run()` method. `fromState` fetches data into the module, while `toState` determines how the module's output updates the pipeline state.

```Groovy
def component = Viash.loadComponent('my-component.nf')
component.run(
    key: 'my-run',
    fromState: [
        fastq_file: 'reads.fq'
    ],
    toState: { id, output, state -> state + [counts: output.counts] }
)
```

--------------------------------

### View Dockerfile for Bash Component

Source: https://viash.io/guide/component/add-dependencies

Displays the Dockerfile used for the Bash component. This file defines the base image, entrypoint, and system dependencies required for the component.

```Bash
target/example_bash_with_setup ---dockerfile
```

```Dockerfile
FROM bash:4.0
ENTRYPOINT []
RUN apk add --no-cache curl wget

LABEL org.opencontainers.image.description="Companion container for running component example_bash_with_setup"
LABEL org.opencontainers.image.created="2025-10-10T13:50:15Z"
```

--------------------------------

### Example Bash Script for Text Processing

Source: https://viash.io/quickstart

An example Bash script for the 'remove_comments' Viash component. This script is designed to read an input file, remove lines starting with '#', and write the result to an output file. It demonstrates basic file processing in Bash.

```bash
#!/bin/bash

# Input and output file paths are expected as arguments
INPUT_FILE=$1
OUTPUT_FILE=$2

# Remove lines starting with '#' and save to output file
grep -v '^#' "$INPUT_FILE" > "$OUTPUT_FILE"

# Exit with success status
exit 0

```

--------------------------------

### Add User to Docker Group

Source: https://viash.io/installation

Adds the current user to the 'docker' group, allowing them to run Docker commands without sudo. A re-login is required for the changes to take effect.

```shell
sudo usermod -aG docker $USER
```

--------------------------------

### Apply Engine to Viash Components

Source: https://viash.io/reference/cli/ns_exec

This example shows how to use the `--apply_engine` option to execute a command for each Viash component, specifically targeting and applying each engine found in the config files. The `{engine}` and `{output}` placeholders are automatically filled.

```shell
viash ns exec --apply_engine --engine "^python$" 'echo "Engine: {engine}, Output: {output}" \;'
```

--------------------------------

### Run Commands in Dockerfile

Source: https://viash.io/reference/config/engines/docker/setup/dockerRequirements

Defines `RUN` instructions to be executed during the Docker image build. This is useful for installing packages or performing other setup tasks. Accepts a string or a list of strings, supporting multi-line commands.

```yaml
run: |
  echo 'Run a custom command'
  echo 'Foo' > /path/to/file.txt
```

--------------------------------

### Run Unit Tests with Viash (Bash Example)

Source: https://viash.io/guide/component/unit-testing

This snippet demonstrates how to run unit tests for a Viash project using the `viash test` command with a configuration file. It shows a typical output when tests are executed in a temporary directory, including Docker build processes and file operations.

```bash
viash test config.vsh.yaml
```

--------------------------------

### Execute Custom R Script

Source: https://viash.io/reference/config/engines/docker/setup/rRequirements

Allows execution of custom R code during the build process. This can be used for complex setup tasks or running specific R commands. The code block is executed directly.

```yaml
script: |
  cat("Running custom code\n")
  install.packages("anndata")
```

--------------------------------

### Viash Docker Setup Strategies

Source: https://viash.io/guide/component/create-component

Lists the available strategies for setting up Docker containers within Viash. These options control how the Docker image is built or pulled.

```plaintext
---setup=STRATEGY
        Setup the docker container. Options are: alwaysbuild, alwayscachedbuild, ifneedbebuild, ifneedbecachedbuild, alwayspull, alwayspullelsebuild, alwayspullelsecachedbuild, ifneedbepull, ifneedbepullelsebuild, ifneedbepullelsecachedbuild, push, pushifnotpresent, donothing.
        Default: ifneedbepullelsecachedbuild
```

--------------------------------

### Set Docker Entrypoint (Shell Format)

Source: https://viash.io/reference/config/engines/docker

Demonstrates setting the Docker container's entrypoint using the shell format. This is a string-based alternative to the exec format.

```yaml
entrypoint: "top -b"
```

--------------------------------

### Set Example Value for Boolean Argument

Source: https://viash.io/reference/config/arguments/boolean

This example shows how to specify an example value for a boolean argument. If no 'default' property is defined, this 'example' value will be used as the default.

```yaml
- name: --my_boolean
  type: boolean
  example: true
```

--------------------------------

### Set Example Value for Double Argument

Source: https://viash.io/reference/config/arguments/double

This example shows how to specify an example value for a 'double' type argument. If no default value is provided, this example value will be used.

```yaml
- name: --my_double
  type: double
  example: 5.8
```

--------------------------------

### Viash `.run()`: Automatic Processing and Debugging Options

Source: https://viash.io/reference/nextflow_vdsl3/import_module

Details the use of `auto` options (like `simplifyInput`, `simplifyOutput`, `publish`, `transcript`) and the `debug` flag in the `.run()` method for controlling automated tasks and verbosity. These simplify common pipeline operations.

```Groovy
def component = Viash.loadComponent('my-component.nf')
component.run(
    key: 'my-run',
    auto: [
        simplifyInput: true,
        simplifyOutput: true,
        publish: true,
        transcript: true
    ],
    debug: true
)
```

--------------------------------

### Import and Use Python Helper Functions

Source: https://viash.io/guide/component/use-helper-functions

This Python example illustrates importing helper functions within a Viash environment. It sets up input and output parameters and appends the resource directory to the system path to import and use a 'copy_file' function from a helper module.

```python
import sys

## VIASH START
par = {
  'input': 'file.txt',
  'output': 'output.txt'
}
## VIASH END

# import helper function
sys.path.append(meta['resources_dir'])
from helper import copy_file

# copy file
copy_file(par['input'], par['output'])

```

--------------------------------

### Install R Packages from CRAN

Source: https://viash.io/reference/config/engines/docker/setup/rRequirements

Specifies R packages to install from the Comprehensive R Archive Network (CRAN). Supports single package names or lists of packages. This is a common method for installing stable R package versions.

```yaml
cran: [ anndata, ggplot2 ]
```

```yaml
packages: [ anndata, ggplot2 ]
```

--------------------------------

### Run Python Executable with Input/Output

Source: https://viash.io/guide/component/create-component

This example shows how to execute a Viash-generated Python script, specifying input and output files via command-line arguments. It includes the command to run the script and the subsequent file listing, indicating successful execution.

```python
target/example_python --input config.vsh.yaml --output output.txt
```

```text
Copying '/viash_automount/tmp/Rtmp7GQqUa/create_new_component8d4e13c7eb41/python/config.vsh.yaml' to '/viash_automount/tmp/Rtmp7GQqUa/create_new_component8d4e13c7eb41/python/output.txt'.
```

```text
ls -l
total 20
-rw-r--r-- 1 runner runner  423 Oct 10 13:47 config.vsh.yaml
-rw-r--r-- 1 runner runner  423 Oct 10 13:48 foo.txt
-rw-r--r-- 1 runner runner  423 Oct 10 13:49 output.txt
-rwxr-xr-x 1 runner runner  216 Oct 10 13:47 script.py
drwxr-xr-x 2 runner runner 4096 Oct 10 13:49 target
```

--------------------------------

### Example Nextflow Configuration for Viash Workflow

Source: https://viash.io/quickstart

A Nextflow configuration file (`nextflow.config`) used within a Viash project. This file typically defines process configurations, plugin management, and other pipeline-level settings for Nextflow.

```groovy
plugins {
    id "nf-tower" version "2.+'"
}

process.container = 'docker.io/library/ubuntu:latest' // Example default container
workDir = "work"

// Example process configuration
params.output_dir = "results"

process.executor = 'local'

```

--------------------------------

### Install R Packages from SVN URI

Source: https://viash.io/reference/config/engines/docker/setup/rRequirements

Installs R packages using a Subversion (SVN) URI. This is less common but provides compatibility with SVN repositories.

```yaml
svn: [ https://path.to.svn/group/repo ]
```

--------------------------------

### Install Python Packages from GitLab

Source: https://viash.io/reference/config/engines/docker/setup/pythonRequirements

Specifies Python packages to be installed directly from GitLab repositories. Similar to GitHub, this enables installation from specific project paths.

```yaml
gitlab: [ foo/bar ]
```

--------------------------------

### Install R Packages from Bioconductor

Source: https://viash.io/reference/config/engines/docker/setup/rRequirements

Installs R packages from Bioconductor, a repository for bioinformatics software. Accepts single package names or lists. Includes an option to force reinstallation.

```yaml
bioc: [ AnnotationDbi, SingleCellExperiment ]
```

```yaml
bioc_force_install: false
```

--------------------------------

### View Dockerfile for C# Component

Source: https://viash.io/guide/component/add-dependencies

Displays the Dockerfile used for the C# component. This file specifies the .NET script base image and necessary system packages.

```Bash
target/example_csharp_with_setup ---dockerfile
```

```Dockerfile
FROM ghcr.io/data-intuitive/dotnet-script:1.3.1
ENTRYPOINT []
RUN apk add --no-cache curl wget

LABEL org.opencontainers.image.description="Companion container for running component example_csharp_with_setup"
LABEL org.opencontainers.image.created="2025-10-10T13:50:20Z"
```

--------------------------------

### Define Apt Packages List in Viash IO

Source: https://viash.io/reference/config/engines/docker/setup/aptRequirements

This snippet shows how to list apt packages that need to be installed for a Viash IO component. It can accept a single package name or a list of package names. Dependencies include the Viash IO framework.

```yaml
packages: [ sl ]
```

--------------------------------

### Define Long Argument with an Example Value

Source: https://viash.io/reference/config/arguments/long

This example shows how to provide an example value for a 'long' argument. This serves as a hint for users and can be used as a default if no explicit 'default' property is set.

```yaml
- name: --my_long
  type: long
  example: 100
```

--------------------------------

### Clone Viash Template Project

Source: https://viash.io/quickstart

Clones the Viash template repository from GitHub and changes the directory to the newly cloned project. This is the initial step for setting up a new Viash project.

```bash
git clone https://github.com/youruser/my_first_pipeline.git && cd my_first_pipeline
```

--------------------------------

### List Project Files

Source: https://viash.io/quickstart

Lists the files and directories in the current project directory using 'ls -l'. This command shows the contents of the project after the Viash build process, including the newly created 'target' directory.

```bash
ls -l
```

--------------------------------

### Example Viash Package Configuration (_viash.yaml)

Source: https://viash.io/guide/project/package-config

Defines project-wide settings for a Viash package, including name, organization, version, metadata, and Viash-specific configurations like viash_version.

```yaml
# project settings
name: project_template
organization: viash-io
version: 0.3.1
# metadata
description: |
  This is a project template for viash projects.
summary: |
  A project template for viash projects.
keywords: [viash, template]
license: GPL-3.0
links:
  repository: https://github.com/viash-io/viash_project_template
  issue_tracker: https://github.com/viash-io/viash_project_template/issues
  docker_registry: ghcr.io
authors:
  - name: Alice
    roles: [author, maintainer]
  - name: Bob
    roles: [author]
# settings
viash_version: 0.9.4

```

--------------------------------

### Install Python Packages from SVN URI

Source: https://viash.io/reference/config/engines/docker/setup/pythonRequirements

Installs Python packages using an SVN URI. This is for packages hosted in Subversion repositories.

```yaml
svn: [ http://svn.repo/some_pkg/trunk/#egg=SomePackage ]
```

--------------------------------

### Nextflow Runner Configuration Example

Source: https://viash.io/reference/config/runners/nextflow

An example of how to configure the Nextflow runner within a Viash component. This specifies the runner type and associated directives.

```yaml
runners:
  - type: nextflow
    directives:
      label: [lowcpu, midmem]
```

--------------------------------

### Display VDSL3 Module Help Information

Source: https://viash.io/guide/nextflow_vdsl3/create-and-use-a-module

Show the available help information for a VDSL3 module when run as a standalone pipeline. This is useful for understanding the module's parameters and options.

```bash
nextflow run target/main.nf --help
```

--------------------------------

### Install Python Packages from Mercurial URI

Source: https://viash.io/reference/config/engines/docker/setup/pythonRequirements

Installs Python packages using a Mercurial URI. This is for projects managed with Mercurial version control.

```yaml
mercurial: [ https://hg.myproject.org/MyProject/#egg=MyProject ]
```

--------------------------------

### Install Python Packages from GitHub

Source: https://viash.io/reference/config/engines/docker/setup/pythonRequirements

Specifies Python packages to be installed directly from GitHub repositories. This allows for the use of unreleased or specific commits.

```yaml
github: [ jkbr/httpie ]
```
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