Pipeline Developer Guide

Prerequisites

To deploy a bioinformatic pipeline in SP3,

  1. Pipeline code has to be version controlled in a Git repo (github, gitlab or gitea etc.).

  2. Pipeline is written in Nextflow, calling scripting language like shell, python or R etc.

  3. Pipeline has a container with all 3rd party dependencies using either docker or singularity.

A sample of such pipeline is here.

Nextflow Checklist

  • Have an input directory as a parameter (e.g. –input_dir)

  • Have an output directory as a parameter (e.g. –output_dir)

  • Have a file pattern for the input files (e.g. –readpat)

  • Have different profiles for different environment in nextflow.config

  • Have output data explicitly in output channel, do not use *.*

  • Have publishDir in process to explicitly claim final output files

  • Have tag to identify individual sample identifier

  • Have memory usage set for process that has high memory usage, e.g. memory ‘10 G’ for centrifuge

Nextflow Do NOT

  • Do Not write to input directory

  • Do Not write to reference/database directory

  • Do Not write to /tmp, use scratch true instead

  • Do Not write anywhere except nextflow work directory

  • Do Not change work directory

  • Do Not access files outside of channel except reference files

  • Do Not create files outside of channel

  • Do Not have a list of scripts in one process if they do not have to run together.

Docker Checklist

  • Have a folder called Docker for Docker build context, including Docker file and files that needed to be copied into Docker.

  • Build FROM an official and small size image

  • Have LABEL with version, description, maintainer, dockerhub link etc.

  • Split RUN command in lines for better readability

  • Use WORKDIR instead of profiferating instructions like RUN cd && do-something-

Best Docker Practice can be found at Docker Docs.