---
layout: default
navsection: userguide
title: "CWL Resources"
...
{% comment %}
Copyright (C) The Arvados Authors. All rights reserved.

SPDX-License-Identifier: CC-BY-SA-3.0
{% endcomment %}

{% include 'what_is_cwl' %}

{% include 'tutorial_expectations' %}

h2. Developing workflows

For an introduction and and detailed documentation about writing CWL, see the "CWL User Guide":https://www.commonwl.org/user_guide and the "CWL Specification":http://commonwl.org/v1.2 .

See "Writing Portable High-Performance Workflows":{{site.baseurl}}/user/cwl/cwl-style.html and "Arvados CWL Extensions":{{site.baseurl}}/user/cwl/cwl-extensions.html for additional information about using CWL on Arvados.

See "Repositories of CWL Tools and Workflows":https://www.commonwl.org/#Repositories_of_CWL_Tools_and_Workflows for links to repositories of existing tools for reuse.

See "Software for working with CWL":https://www.commonwl.org/#Software_for_working_with_CWL for links to software tools to help create CWL documents.

h2. Using cwltool

When developing a workflow, it is often helpful to run it on the local host to avoid the overhead of submitting to the cluster.  To execute a workflow only on the local host (without submitting jobs to an Arvados cluster) you can use the @cwltool@ command.  Note that when using @cwltool@ you must have the input data accessible on the local file system using either @arv-mount@ or @arv-get@ to fetch the data from Keep.

<notextile>
<pre><code>~/arvados/doc/user/cwl/bwa-mem$ <span class="userinput">arv-get 2463fa9efeb75e099685528b3b9071e0+438/ .</span>
156 MiB / 156 MiB 100.0%
~/arvados/doc/user/cwl/bwa-mem$ <span class="userinput">arv-get ae480c5099b81e17267b7445e35b4bc7+180/ .</span>
23 MiB / 23 MiB 100.0%
~/arvados/doc/user/cwl/bwa-mem$ <span class="userinput">cwltool bwa-mem-input.yml bwa-mem-input-local.yml</span>
cwltool 1.0.20160629140624
[job bwa-mem.cwl] /home/example/arvados/doc/user/cwl/bwa-mem$ docker \
    run \
    -i \
    --volume=/home/example/arvados/doc/user/cwl/bwa-mem/19.fasta.ann:/var/lib/cwl/job979368791_bwa-mem/19.fasta.ann:ro \
    --volume=/home/example/arvados/doc/user/cwl/bwa-mem/HWI-ST1027_129_D0THKACXX.1_1.fastq:/var/lib/cwl/job979368791_bwa-mem/HWI-ST1027_129_D0THKACXX.1_1.fastq:ro \
    --volume=/home/example/arvados/doc/user/cwl/bwa-mem/19.fasta.sa:/var/lib/cwl/job979368791_bwa-mem/19.fasta.sa:ro \
    --volume=/home/example/arvados/doc/user/cwl/bwa-mem/19.fasta.amb:/var/lib/cwl/job979368791_bwa-mem/19.fasta.amb:ro \
    --volume=/home/example/arvados/doc/user/cwl/bwa-mem/19.fasta.pac:/var/lib/cwl/job979368791_bwa-mem/19.fasta.pac:ro \
    --volume=/home/example/arvados/doc/user/cwl/bwa-mem/HWI-ST1027_129_D0THKACXX.1_2.fastq:/var/lib/cwl/job979368791_bwa-mem/HWI-ST1027_129_D0THKACXX.1_2.fastq:ro \
    --volume=/home/example/arvados/doc/user/cwl/bwa-mem/19.fasta.bwt:/var/lib/cwl/job979368791_bwa-mem/19.fasta.bwt:ro \
    --volume=/home/example/arvados/doc/user/cwl/bwa-mem:/var/spool/cwl:rw \
    --volume=/tmp/tmpgzyou9:/tmp:rw \
    --workdir=/var/spool/cwl \
    --read-only=true \
    --log-driver=none \
    --user=1001 \
    --rm \
    --env=TMPDIR=/tmp \
    --env=HOME=/var/spool/cwl \
    biodckr/bwa \
    bwa \
    mem \
    -t \
    1 \
    -R \
    '@RG	ID:arvados_tutorial	PL:illumina	SM:HWI-ST1027_129' \
    /var/lib/cwl/job979368791_bwa-mem/19.fasta \
    /var/lib/cwl/job979368791_bwa-mem/HWI-ST1027_129_D0THKACXX.1_1.fastq \
    /var/lib/cwl/job979368791_bwa-mem/HWI-ST1027_129_D0THKACXX.1_2.fastq > /home/example/arvados/doc/user/cwl/bwa-mem/HWI-ST1027_129_D0THKACXX.1_1.sam
[M::bwa_idx_load_from_disk] read 0 ALT contigs
[M::process] read 100000 sequences (10000000 bp)...
[M::mem_pestat] # candidate unique pairs for (FF, FR, RF, RR): (0, 4745, 1, 0)
[M::mem_pestat] skip orientation FF as there are not enough pairs
[M::mem_pestat] analyzing insert size distribution for orientation FR...
[M::mem_pestat] (25, 50, 75) percentile: (154, 181, 214)
[M::mem_pestat] low and high boundaries for computing mean and std.dev: (34, 334)
[M::mem_pestat] mean and std.dev: (185.63, 44.88)
[M::mem_pestat] low and high boundaries for proper pairs: (1, 394)
[M::mem_pestat] skip orientation RF as there are not enough pairs
[M::mem_pestat] skip orientation RR as there are not enough pairs
[M::mem_process_seqs] Processed 100000 reads in 9.848 CPU sec, 9.864 real sec
[main] Version: 0.7.12-r1039
[main] CMD: bwa mem -t 1 -R @RG	ID:arvados_tutorial	PL:illumina	SM:HWI-ST1027_129 /var/lib/cwl/job979368791_bwa-mem/19.fasta /var/lib/cwl/job979368791_bwa-mem/HWI-ST1027_129_D0THKACXX.1_1.fastq /var/lib/cwl/job979368791_bwa-mem/HWI-ST1027_129_D0THKACXX.1_2.fastq
[main] Real time: 10.061 sec; CPU: 10.032 sec
Final process status is success
{
    "aligned_sam": {
        "size": 30738959,
        "path": "/home/example/arvados/doc/user/cwl/bwa-mem/HWI-ST1027_129_D0THKACXX.1_1.sam",
        "checksum": "sha1$0c668cca45fef02397bb5302880526d300ee4dac",
        "class": "File"
    }
}
</code></pre>
</notextile>

If you get the error @JavascriptException: Long-running script killed after 20 seconds.@ this may be due to the Dockerized Node.js engine taking too long to start.  You may address this by installing Node.js locally (run @apt-get install nodejs@ on Debian or Ubuntu) or by specifying a longer timeout with the @--eval-timeout@ option.  For example, run the workflow with @cwltool --eval-timeout=40@ for a 40-second timeout.