We encourage contributions from the community. To contribute:
1.**Fork the Repository**: Start by forking this repository to your account.
2.**Develop Your Component**: Create your Viash component, ensuring it aligns with our best practices (detailed below).
3.**Submit a Pull Request**: After testing your component, submit a pull request for review.
## Procedure of adding a component
### Step 1: Find a component to contribute
* Find a tool to contribute to this repo.
* Check whether it is already in the [Project board](https://github.com/orgs/viash-hub/projects/1).
* Check whether there is a corresponding [Snakemake wrapper](https://github.com/snakemake/snakemake-wrappers/blob/master/bio) or [nf-core module](https://github.com/nf-core/modules/tree/master/modules/nf-core) which we can use as inspiration.
* Create an issue to show that you are working on this component.
### Step 2: Add config template
Change all occurrences of `xxx` to the name of the component.
Create a file at `src/xxx/config.vsh.yaml` with contents:
```yaml
name: xxx
description: xxx
keywords: [tag1, tag2]
links:
homepage: yyy
documentation: yyy
issue_tracker: yyy
repository: yyy
references:
doi: 12345/12345678.yz
license: MIT/Apache-2.0/GPL-3.0/...
argument_groups:
- name: Inputs
arguments: <...>
- name: Outputs
arguments: <...>
- name: Arguments
arguments: <...>
resources:
- type: bash_script
path: script.sh
test_resources:
- type: bash_script
path: test.sh
- type: file
path: test_data
engines:
- <...>
runners:
- type: executable
- type: nextflow
```
### Step 3: Fill in the metadata
Fill in the relevant metadata fields in the config. Here is an example of the metadata of an existing component.
Google `biocontainer <name of component>` and find the container that is most suitable. Typically the link will be `https://quay.io/repository/biocontainers/xxx?tab=tags`.
If no such container is found, you can create a custom container in the next step.
### Step 5: Create help file
To help develop the component, we store the `--help` output of the tool in a file at `src/xxx/help.txt`.
````bash
cat <<EOF > src/xxx/help.txt
```sh
xxx --help
```
EOF
docker run quay.io/biocontainers/xxx:tag xxx --help >> src/xxx/help.txt
````
Notes:
* This help file has no functional purpose, but it is useful for the developer to see the help output of the tool.
* Some tools might not have a `--help` argument but instead have a `-h` argument. For example, for `arriba`, the help message is obtained by running `arriba -h`:
```bash
docker run quay.io/biocontainers/arriba:2.4.0--h0033a41_2 arriba -h
```
### Step 6: Create or fetch test data
To help develop the component, it's interesting to have some test data available. In most cases, we can use the test data from the Snakemake wrappers.
To make sure we can reproduce the test data in the future, we store the command to fetch the test data in a file at `src/xxx/test_data/script.sh`.
The test data should be suitable for testing this component. Ensure that the test data is small enough: ideally <1KB, preferably <10KB, if need be <100KB.
### Step 7: Add arguments for the input files
By looking at the help file, we add the input arguments to the config file. Here is an example of the input arguments of an existing component.
For instance, in the [arriba help file](src/arriba/help.txt), we see the following:
Check the [documentation](https://viash.io/reference/config/functionality/arguments) for more information on the format of input arguments.
Several notes:
* Argument names should be formatted in `--snake_case`. This means arguments like `--foo-bar` should be formatted as `--foo_bar`, and short arguments like `-f` should receive a longer name like `--foo`.
* Input arguments can have `multiple: true` to allow the user to specify multiple files.
* Preferably, these outputs should not be directories but files. For example, if a tool outputs a directory `foo/` containing files `foo/bar.txt` and `foo/baz.txt`, there should be two output arguments `--bar` and `--baz` (as opposed to one output argument which outputs the whole `foo/` directory).
Finally, add all other arguments to the config file. There are a few exceptions:
* Arguments related to specifying CPU and memory requirements are handled separately and should not be added to the config file.
* Arguments related to printing the information such as printing the version (`-v`, `--version`) or printing the help (`-h`, `--help`) should not be added to the config file.
* Prefer using `boolean_true` over `boolean_false`. This avoids confusion when specifying values for this argument in a Nextflow workflow.
For example, consider the CLI option `--no-indels` for `cutadapt`. If the config for `cutadapt` would specify an argument `no_indels` of type `boolean_false`,
the script of the component must pass a `--no-indels` argument to `cutadapt` when `par_no_indels` is set to `false`. This becomes problematic setting a value for this argument using `fromState` in a nextflow workflow: with `fromState: ["no_indels": true]`, the value that gets passed to the script is `true` and the `--no-indels` flag would *not* be added to the options for `cutadapt`. This is inconsitent to what one might expect when interpreting `["no_indels": true]`.
When using `boolean_true`, the reasoning becomes simpler because its value no longer represents the effect of the argument, but wether or not the flag is set.
To ensure reproducibility of components, we require that all components are run in a Docker container.
```yaml
engines:
- type: docker
image: quay.io/biocontainers/xxx:0.1.0--py_0
```
The container should have your tool installed, as well as `ps`.
If you didn't find a suitable container in the previous step, you can create a custom container. For example:
```yaml
engines:
- type: docker
image: python:3.10
setup:
- type: python
packages: numpy
```
For more information on how to do this, see the [documentation](https://viash.io/guide/component/add-dependencies.html#steps-for-creating-a-custom-docker-platform).
Here is a list of base containers we can recommend:
Next, we need to write a runner script that runs the tool with the input arguments. Create a Bash script named `src/xxx/script.sh` which runs the tool with the input arguments.
When building a Viash component, Viash will automatically replace the `## VIASH START` and `## VIASH END` lines (and anything in between) with environment variables based on the arguments specified in the config.
As an example, this is what the Bash script for the `arriba` component looks like:
* If your arguments can contain special variables (e.g. `$`), you can use quoting (need to find a documentation page for this) to make sure you can use the string as input. Example: `-x ${par_bam@Q}`.
* Optional arguments can be passed to the command conditionally using Bash [parameter expansion](https://www.gnu.org/software/bash/manual/html_node/Shell-Parameter-Expansion.html). For example: `${par_known_fusions:+-k ${par_known_fusions@Q}}`
* If your tool allows for multiple inputs using a separator other than `;` (which is the default Viash multiple separator), you can substitute these values with a command like: `par_disable_filters=$(echo $par_disable_filters | tr ';' ',')`.
* If you have a lot of boolean variables that you would like to unset when the value is `false`, you can avoid duplicate code by using the following syntax:
Create a test script at `src/xxx/test.sh` that runs the component with the test data. This script should run the component (available with `$meta_executable`) with the test data and check if the output is as expected. The script should exit with a non-zero exit code if the output is not as expected. For example:
