In order to execute a workflow on AWS, follow these instructions in order to create a Nextflow config file. We recommend creating this file in a location that will be easy to reference for multiple projects, since it will not contain any information that is specific to any particular workflow or dataset.

In case you end up using multiple configuration files to coordinate execution on other systems (e.g. SLURM), we recommend naming this configuration file something like nextflow.aws.config.

Setting up AWS Credentials

In order to run jobs on AWS Batch and access data in AWS S3, Nextflow can directly use the credentials set up for you by the Cloud and Data team.

You should have received an encrypted email containing your AWS credentials (if not contact helpdesk). Those credentials will be used by Nextflow when executing a workflow.

Expert Level: Multiple AWS Profiles

If you have multiple profiles in your AWS configuration, you can set the environment variable AWS_PROFILE to indicate which should be used for a particular workflow.

Work Directory

You need to select a work directory (or workDir), which will contain the temporary files produced during the course of workflow execution. This will not contain any of the final output files, and so it should be located in a path which is easy to clean up and delete on an as-needed basis. It is also possible to set up folders in AWS S3 which are automatically deleted after a set period of time (similar to the delete* folders in /fh/scratch/), which may be appropriate for your group.

A typical workDir may be s3://fh-pi-lastname-f-eco/nextflow/work/.

Nextflow Configuration - AWS

Below is a template configuration file which can be used as your nextflow.aws.config. Please make sure to replace every placeholder value (e.g. <WORK_DIR>), including the < and > characters.

workDir = "<WORK_DIR>"

aws {
    region = 'us-west-2'
    batch {
        maxTransferAttempts = 3
        cliPath = '/home/ec2-user/miniconda/bin/aws'
        volumes = ['/var/lib/docker:/tmp:rw']
        maxParallelTransfers = 3
    }
    client {
        maxConnections = 4
    }
}

process {
    queue = "default"
    executor = "awsbatch"
}

If you have any problems using this configuration, please don’t hesitate to get in touch.

Running the workflow

To run a workflow with this configuration, follow the guidance for formatting the appropriate run script.