-* When migrating from crunch v1 API (--api=jobs) to the crunch v2 API (--api=containers) there are a few differences in behavior:
-** The tool is limited to accessing only collections which are explicitly listed in the input, and further limited to only the subdirectories of collections listed in input. For example, given an explicit file input @/dir/subdir/file1.txt@, a tool will not be able to implicitly access the file @/dir/file2.txt@. Use @secondaryFiles@ or a @Directory@ input to describe trees of files.
-** Files listed in @InitialWorkDirRequirement@ appear in the output directory as normal files (not symlinks) but cannot be moved, renamed or deleted. These files will be added to the output collection but without any additional copies of the underlying data.
-** Tools are disallowed network access by default. Tools which require network access must include @arv:APIRequirement: {}@ in their @requirements@ section.
+To write workflows that are easy to modify and portable across CWL runners (in the event you need to share your workflow with others), there are several best practices to follow:
+
+Workflows should always provide @DockerRequirement@ in the @hints@ or @requirements@ section.
+
+Build a reusable library of components. Share tool wrappers and subworkflows between projects. Make use of and contribute to "community maintained workflows and tools":https://github.com/common-workflow-language/workflows and tool registries such as "Dockstore":http://dockstore.org .
+
+CommandLineTools wrapping custom scripts should represent the script as an input parameter with the script file as a default value. Use @secondaryFiles@ for scripts that consist of multiple files. For example:
+
+{% codeblock as yaml %}
+cwlVersion: v1.0
+class: CommandLineTool
+baseCommand: python
+inputs:
+ script:
+ type: File
+ inputBinding: {position: 1}
+ default:
+ class: File
+ location: bclfastq.py
+ secondaryFiles:
+ - class: File
+ location: helper1.py
+ - class: File
+ location: helper2.py
+ inputfile:
+ type: File
+ inputBinding: {position: 2}
+outputs:
+ out:
+ type: File
+ outputBinding:
+ glob: "*.fastq"
+{% endcodeblock %}
+
+You can get the designated temporary directory using @$(runtime.tmpdir)@ in your CWL file, or from the @$TMPDIR@ environment variable in your script.
+
+Similarly, you can get the designated output directory using $(runtime.outdir), or from the @HOME@ environment variable in your script.
+
+Avoid specifying resource requirements in CommandLineTool. Prefer to specify them in the workflow. You can provide a default resource requirement in the top level @hints@ section, and individual steps can override it with their own resource requirement.
+
+{% codeblock as yaml %}
+cwlVersion: v1.0
+class: Workflow
+inputs:
+ inp: File
+hints:
+ ResourceRequirement:
+ ramMin: 1000
+ coresMin: 1
+ tmpdirMin: 45000
+steps:
+ step1:
+ in: {inp: inp}
+ out: [out]
+ run: tool1.cwl
+ step2:
+ in: {inp: step1/inp}
+ out: [out]
+ run: tool2.cwl
+ hints:
+ ResourceRequirement:
+ ramMin: 2000
+ coresMin: 2
+ tmpdirMin: 90000
+{% endcodeblock %}