WDL Task Runtime Style Guide Overview

This style guide provides formatting guidelines and best practices for the runtime block of a WDL workflow task. For more information about scripting in WDL, see the WDL 1.0 Specification.

Variables and suggested configurations

• Disk
  • Set in GiB
  • Variable type is Int
  • Use local-disk and HDD
  • Default should be dynamically set based on task inputs
  • Variable name should be disk_size_gb
• Memory
  • Set in MiB
  • Variable type is Int
  • Default should be dynamically set based on task inputs
  • Variable name should be memory_mb
• CPU
  • Default set to 1
  • Variable name should be cpu
• Docker
  • Variable name should be docker

Example task input

Include runtime variables in the task inputs. Always provide a default value. Separate runtime variables from task inputs with one blank line.

    input {
        File example_file

        String docker = "us.gcr.io/path/to/docker"
        Int cpu = 1
        Int memory_mb = ceil(size(example_file, "MiB"))
        Int disk_size_db = ceil(size(example_file, "GiB"))
    }

Example task runtime

Runtime block should be positioned between the command and output blocks of the task.

    runtime {
        docker: docker
        cpu: cpu
        memory: "${memory_mb} MiB"
        disks: "local-disk ${disk_size_gb} HDD"
    }