fix: Use dynamically generated placeholders

workflow/common/placeholder.go

@@ -0,0 +1,20 @@
+package common
+
+import "fmt"
+
+// placeholderGenerator is to generate dynamically-generated placeholder strings.
+type placeholderGenerator struct {
+	index int
+}
+
+// NewPlaceholderGenerator returns a placeholderGenerator.
+func NewPlaceholderGenerator() *placeholderGenerator {
+	return &placeholderGenerator{}
+}
+
+// NextPlaceholder returns an arbitrary string to perform mock substitution of variables
+func (p *placeholderGenerator) NextPlaceholder() string {
+	s := fmt.Sprintf("placeholder-%d", p.index)
+	p.index = p.index + 1
+	return s
+}

workflow/common/placeholder_test.go

@@ -0,0 +1,15 @@
+package common
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+// TestNextPlaceholder verifies dynamically-generated placeholder strings.
+func TestNextPlaceholder(t *testing.T) {
+	pg := NewPlaceholderGenerator()
+	assert.Equal(t, pg.NextPlaceholder(), "placeholder-0")
+	assert.Equal(t, pg.NextPlaceholder(), "placeholder-1")
+	assert.Equal(t, pg.NextPlaceholder(), "placeholder-2")
+}

workflow/validate/validate.go

@@ -49,9 +49,9 @@ type templateValidationCtx struct {
 
 func newTemplateValidationCtx(wf *wfv1.Workflow, opts ValidateOpts) *templateValidationCtx {
 	globalParams := make(map[string]string)
-	globalParams[common.GlobalVarWorkflowName] = placeholderValue
-	globalParams[common.GlobalVarWorkflowNamespace] = placeholderValue
-	globalParams[common.GlobalVarWorkflowUID] = placeholderValue
+	globalParams[common.GlobalVarWorkflowName] = placeholderGenerator.NextPlaceholder()
+	globalParams[common.GlobalVarWorkflowNamespace] = placeholderGenerator.NextPlaceholder()
+	globalParams[common.GlobalVarWorkflowUID] = placeholderGenerator.NextPlaceholder()
 	return &templateValidationCtx{
 		ValidateOpts: opts,
 		globalParams: globalParams,
@@ -61,19 +61,20 @@ func newTemplateValidationCtx(wf *wfv1.Workflow, opts ValidateOpts) *templateVal
 }
 
 const (
-	// placeholderValue is an arbitrary string to perform mock substitution of variables
-	placeholderValue = "placeholder"
-
 	// anyItemMagicValue is a magic value set in addItemsToScope() and checked in
 	// resolveAllVariables() to determine if any {{item.name}} can be accepted during
 	// variable resolution (to support withParam)
 	anyItemMagicValue = "item.*"
 )
 
+var (
+	placeholderGenerator = common.NewPlaceholderGenerator()
+)
+
 type FakeArguments struct{}
 
 func (args *FakeArguments) GetParameterByName(name string) *wfv1.Parameter {
-	s := placeholderValue
+	s := placeholderGenerator.NextPlaceholder()
 	return &wfv1.Parameter{Name: name, Value: &s}
 }
 
@@ -107,16 +108,16 @@ func ValidateWorkflow(wftmplGetter templateresolution.WorkflowTemplateNamespaced
 			if param.Value != nil {
 				ctx.globalParams["workflow.parameters."+param.Name] = *param.Value
 			} else {
-				ctx.globalParams["workflow.parameters."+param.Name] = placeholderValue
+				ctx.globalParams["workflow.parameters."+param.Name] = placeholderGenerator.NextPlaceholder()
 			}
 		}
 	}
 
 	for k := range wf.ObjectMeta.Annotations {
-		ctx.globalParams["workflow.annotations."+k] = placeholderValue
+		ctx.globalParams["workflow.annotations."+k] = placeholderGenerator.NextPlaceholder()
 	}
 	for k := range wf.ObjectMeta.Labels {
-		ctx.globalParams["workflow.labels."+k] = placeholderValue
+		ctx.globalParams["workflow.labels."+k] = placeholderGenerator.NextPlaceholder()
 	}
 
 	if wf.Spec.Priority != nil {
@@ -132,7 +133,7 @@ func ValidateWorkflow(wftmplGetter templateresolution.WorkflowTemplateNamespaced
 	}
 	if wf.Spec.OnExit != "" {
 		// now when validating onExit, {{workflow.status}} is now available as a global
-		ctx.globalParams[common.GlobalVarWorkflowStatus] = placeholderValue
+		ctx.globalParams[common.GlobalVarWorkflowStatus] = placeholderGenerator.NextPlaceholder()
 		_, err = ctx.validateTemplateHolder(&wfv1.Template{Template: wf.Spec.OnExit}, tmplCtx, &wf.Spec.Arguments, map[string]interface{}{})
 		if err != nil {
 			return err
@@ -195,8 +196,8 @@ func (ctx *templateValidationCtx) validateTemplate(tmpl *wfv1.Template, tmplCtx
 	}
 	localParams := make(map[string]string)
 	if tmpl.IsPodType() {
-		localParams[common.LocalVarPodName] = placeholderValue
-		scope[common.LocalVarPodName] = placeholderValue
+		localParams[common.LocalVarPodName] = placeholderGenerator.NextPlaceholder()
+		scope[common.LocalVarPodName] = placeholderGenerator.NextPlaceholder()
 	}
 	if tmpl.IsLeaf() {
 		for _, art := range tmpl.Outputs.Artifacts {
@@ -651,15 +652,15 @@ func (ctx *templateValidationCtx) addOutputsToScope(tmpl *wfv1.Template, prefix
 		if param.GlobalName != "" && !isParameter(param.GlobalName) {
 			globalParamName := fmt.Sprintf("workflow.outputs.parameters.%s", param.GlobalName)
 			scope[globalParamName] = true
-			ctx.globalParams[globalParamName] = placeholderValue
+			ctx.globalParams[globalParamName] = placeholderGenerator.NextPlaceholder()
 		}
 	}
 	for _, art := range tmpl.Outputs.Artifacts {
 		scope[fmt.Sprintf("%s.outputs.artifacts.%s", prefix, art.Name)] = true
 		if art.GlobalName != "" && !isParameter(art.GlobalName) {
 			globalArtName := fmt.Sprintf("workflow.outputs.artifacts.%s", art.GlobalName)
 			scope[globalArtName] = true
-			ctx.globalParams[globalArtName] = placeholderValue
+			ctx.globalParams[globalArtName] = placeholderGenerator.NextPlaceholder()
 		}
 	}
 	if aggregate {

workflow/validate/validate_test.go

@@ -1908,3 +1908,45 @@ func TestAutomountServiceAccountTokenUse(t *testing.T) {
 		assert.EqualError(t, err, "templates.whalesay.executor.serviceAccountName must not be empty if automountServiceAccountToken is false")
 	}
 }
+
+var templateResolutionWithPlaceholderWorkflow = `
+apiVersion: argoproj.io/v1alpha1
+kind: Workflow
+metadata:
+  generateName: template-resolution-with-placeholder-
+spec:
+  entrypoint: template-resolution
+  arguments:
+    parameters:
+    - name: foo
+      value: /mnt/foo
+    - name: bar
+      value: /mnt/bar
+  volumes:
+  - name: workdir
+    emptyDir: {}
+  templates:
+  - name: template-resolution
+    template: multi-volume-mounts
+  - name: multi-volume-mounts
+    inputs:
+      parameters:
+      - name: foo
+      - name: bar
+    container:
+      image: debian:latest
+      volumeMounts:
+      - name: workdir
+        mountPath: "{{inputs.parameters.foo}}"
+      - name: workdir
+        mountPath: "{{inputs.parameters.bar}}"
+`
+
+// TestTemplateResolutionWithPlaceholderWorkflow verifies the placeholder use during a validation process.
+func TestTemplateResolutionWithPlaceholderWorkflow(t *testing.T) {
+	{
+		wf := unmarshalWf(templateResolutionWithPlaceholderWorkflow)
+		err := ValidateWorkflow(wftmplGetter, wf, ValidateOpts{})
+		assert.NoError(t, err)
+	}
+}