......

defaults

+{
+    "docker": "registry.cn-shanghai.aliyuncs.com/pgx-docker-registry/r-base:4.0.2",
+    "disk_size": "200",
+    "cluster_config": "OnDemand bcs.a2.large img-ubuntu-vpc"
+}

inputs

+{
+  "{{ project_name }}.docker": "{{ docker }}",
+  "{{ project_name }}.file": "{{ file }}",
+  "{{ project_name }}.disk_size": "{{ disk_size }}",
+  "{{ project_name }}.cluster_config": "{{ cluster_config }}",
+  "{{ project_name }}.sample_id": "{{ sample_id }}",
+  "{{ project_name }}.number": "{{ number }}"
+}
+

tasks/Downsampling.wdl

+task Downsampling {
+
+	File file
+	String sample_id
+	Int number
+	String docker
+	String cluster_config
+	String disk_size
+
+	command <<<
+		number = expr $number \* 4 
+		zcat ${file}|head -n ${number} |gzip > ${sample_id}.gz
+	>>>
+
+	runtime {
+		docker: docker
+		cluster: cluster_config
+		systemDisk: "cloud_ssd 40"
+		dataDisk: "cloud_ssd " + disk_size + " /cromwell_root/"
+	}
+
+	output {
+		File Downsampling = "${sample_id}.gz"
+	}
+}

workflow.wdl

+import "./tasks/Downsampling.wdl" as Downsampling
+
+workflow {{ project_name }} {
+	File file
+	String sample_id
+	String docker
+	String cluster_config
+	String disk_size
+	Int number
+
+	call Downsampling.Downsampling as Downsampling {
+		input:
+		file = file,
+		docker = docker,
+		disk_size = disk_size,
+		cluster_config=cluster_config,
+		sample_id=sample_id,
+		number=number
+	}
+}