Nextstrain build for novel coronavirus SARS-CoV-2
Source code
Contributors
Latest commits
Pages

Developer guide

Contents

  1. Setup
  2. Data
  3. Running
  4. Releasing new workflow versions

Setup

Please see the main Nextstrain docs for instructions for installing the Nextstrain bioinformatics pipeline (Augur) and visualization tools (Auspice).

Data

In order to run the Nextstrain build you must provision ./data/sequences.fasta and ./data/metadata.tsv. We’ve included a test set of sequences that are publicly available via Genbank as ./example_data/sequences.fasta.

Running

Please see these docs for instructions on how to run this build yourself.

The resulting output JSON at auspice/ncov.json can be visualized by running auspice view --datasetDir auspice or nextstrain view auspice/ depending on local vs containerized installation.

Finalizing automated builds

To run a regional build, be sure to update the list of regions in nextstrain_profiles/nextstrain-gisaid/builds.yaml. You can run all builds in parallel with the following command.

snakemake --profile nextstrain_profiles/nextstrain-gisaid all_regions

Or you can specify final or intermediate output files like so:

# subsampled regional focal
snakemake --profile nextstrain_profiles/nextstrain-gisaid auspice/ncov_europe.json

# subsampled global
snakemake --profile nextstrain_profiles/nextstrain-gisaid auspice/ncov_global.json

To update ordering/lat_longs after AWS download:

snakemake --touch --forceall --profile nextstrain_profiles/nextstrain-gisaid
snakemake --profile nextstrain_profiles/nextstrain-gisaid clean_export_regions
snakemake --profile nextstrain_profiles/nextstrain-gisaid export_all_regions

When done adjusting lat-longs & orders, remember to run the following command to produce the final Auspice files.

snakemake --profile nextstrain_profiles/nextstrain-gisaid all_regions

Releasing new workflow versions

We use semantic versioning of the ncov workflow, denoting backward incompatible changes with major versions. Prior to merging a pull request that introduces a new backward incompatible change (e.g., requirement of a new version of Augur), take the following steps to document these changes:

  1. Determine the new version number by incrementing the current version (e.g., “v2” from “v1”).
  2. As part of the pull request, document the change(s) from the pull request in docs/src/reference/change_log.md with the current date and new version number.
  3. Merge the pull request
  4. Create a new GitHub release using the new version as the tag (e.g., “v2”) and release title. Leave the release description empty.

We do not release new minor versions for new features, but you should document new features in the change log as part of the corresponding pull request under a heading for the date those features are merged.

Triggering routine builds

Typically, everything’s triggered from the ncov-ingest pipeline’s trigger command. After updating the intermediate files, that command will run this ncov pipeline force-requiring the rules deploy and upload.

Triggering trial builds

This repository contains a GitHub Action trial-build which is manually run via github.com. This will ask for a “trial name” and upload intermediate files to nextstrain-ncov-private/trial/$TRIAL_NAME and nextstrain-staging/files/ncov/open/trial/$TRIAL_NAME. Auspice datasets for visualisation will be available at https://nextstrain.org/staging/ncov/gisaid/trial/$TRIAL_NAME/$BUILD_NAME and https://nextstrain.org/staging/ncov/open/trial/$TRIAL_NAME/$BUILD_NAME.