[TEP-0144] Add enum API field

Part of [#7270][#7270]. In [TEP-0144][tep-0144] we proposed a new `enum` field to support built-in param input validation.

This commit adds the `Enum` api field, validation and conversion logic.

/kind feature

[#7270]: #7270
[tep-0144]: https://github.com/tektoncd/community/blob/main/teps/0144-param-enum.md

docs/pipeline-api.md

@@ -1691,6 +1691,19 @@ default is set, a Task may be executed without a supplied value for the
 parameter.</p>
 </td>
 </tr>
+<tr>
+<td>
+<code>enum</code><br/>
+<em>
+[]string
+</em>
+</td>
+<td>
+<em>(Optional)</em>
+<p>Enum declares a set of allowed param input values for tasks/pipelines that can be validated.
+If Enum is not set, no input validation is performed for the param.</p>
+</td>
+</tr>
 </tbody>
 </table>
 <h3 id="tekton.dev/v1.ParamSpecs">ParamSpecs
@@ -9963,6 +9976,19 @@ default is set, a Task may be executed without a supplied value for the
 parameter.</p>
 </td>
 </tr>
+<tr>
+<td>
+<code>enum</code><br/>
+<em>
+[]string
+</em>
+</td>
+<td>
+<em>(Optional)</em>
+<p>Enum declares a set of allowed param input values for tasks/pipelines that can be validated.
+If Enum is not set, no input validation is performed for the param.</p>
+</td>
+</tr>
 </tbody>
 </table>
 <h3 id="tekton.dev/v1beta1.ParamSpecs">ParamSpecs

hack/ignored-openapi-violations.list

@@ -41,3 +41,5 @@ API rule violation: names_match,github.com/tektoncd/pipeline/pkg/apis/resolution
 API rule violation: list_type_missing,github.com/tektoncd/pipeline/pkg/apis/pipeline/v1alpha1,RunSpec,Workspaces
 API rule violation: list_type_missing,github.com/tektoncd/pipeline/pkg/apis/pipeline/v1alpha1,VerificationPolicySpec,Authorities
 API rule violation: list_type_missing,github.com/tektoncd/pipeline/pkg/apis/pipeline/v1alpha1,VerificationPolicySpec,Resources
+API rule violation: list_type_missing,github.com/tektoncd/pipeline/pkg/apis/pipeline/v1beta1,ParamSpec,Enum
+API rule violation: list_type_missing,github.com/tektoncd/pipeline/pkg/apis/pipeline/v1,ParamSpec,Enum

pkg/apis/pipeline/v1/param_types.go

@@ -22,6 +22,7 @@ import (
 	"fmt"
 	"strings"
 
+	"github.com/tektoncd/pipeline/pkg/apis/config"
 	"github.com/tektoncd/pipeline/pkg/substitution"
 	corev1 "k8s.io/api/core/v1"
 	"k8s.io/apimachinery/pkg/util/sets"
@@ -53,6 +54,10 @@ type ParamSpec struct {
 	// parameter.
 	// +optional
 	Default *ParamValue `json:"default,omitempty"`
+	// Enum declares a set of allowed param input values for tasks/pipelines that can be validated.
+	// If Enum is not set, no input validation is performed for the param.
+	// +optional
+	Enum []string `json:"enum,omitempty"`
 }
 
 // ParamSpecs is a list of ParamSpec
@@ -132,22 +137,47 @@ func (ps ParamSpecs) sortByType() (ParamSpecs, ParamSpecs, ParamSpecs) {
 
 // validateNoDuplicateNames returns an error if any of the params have the same name
 func (ps ParamSpecs) validateNoDuplicateNames() *apis.FieldError {
+	var errs *apis.FieldError
 	names := ps.getNames()
-	seen := sets.String{}
-	dups := sets.String{}
+	for dup := range findDups(names) {
+		errs = errs.Also(apis.ErrGeneric("parameter appears more than once", "").ViaFieldKey("params", dup))
+	}
+	return errs
+}
+
+// validateParamEnum validates feature flag, duplication and allowed types for Param Enum
+func (ps ParamSpecs) validateParamEnums(ctx context.Context) *apis.FieldError {
 	var errs *apis.FieldError
-	for _, n := range names {
-		if seen.Has(n) {
-			dups.Insert(n)
+	for _, p := range ps {
+		if len(p.Enum) == 0 {
+			continue
+		}
+		if !config.FromContextOrDefaults(ctx).FeatureFlags.EnableParamEnum {
+			errs = errs.Also(errs, apis.ErrGeneric(fmt.Sprintf("feature flag `%s` should be set to true to use Enum", config.EnableParamEnum), "").ViaFieldKey("params", p.Name))
+		}
+		if p.Type != ParamTypeString {
+			errs = errs.Also(apis.ErrGeneric("enum can only be set with string type param", "").ViaFieldKey("params", p.Name))
+		}
+		for dup := range findDups(p.Enum) {
+			errs = errs.Also(apis.ErrGeneric(fmt.Sprintf("parameter enum value %v appears more than once", dup), "").ViaFieldKey("params", p.Name))
 		}
-		seen.Insert(n)
-	}
-	for n := range dups {
-		errs = errs.Also(apis.ErrGeneric("parameter appears more than once", "").ViaFieldKey("params", n))
 	}
 	return errs
 }
 
+// findDups returns the duplicate element in the given slice
+func findDups(vals []string) sets.String {
+	seen := sets.String{}
+	dups := sets.String{}
+	for _, val := range vals {
+		if seen.Has(val) {
+			dups.Insert(val)
+		}
+		seen.Insert(val)
+	}
+	return dups
+}
+
 // Param declares an ParamValues to use for the parameter called name.
 type Param struct {
 	Name  string     `json:"name"`

pkg/apis/pipeline/v1/pipeline_types_test.go

@@ -508,10 +508,9 @@ func TestPipelineTask_ValidateCustomTask(t *testing.T) {
 
 func TestPipelineTask_ValidateRegularTask_Success(t *testing.T) {
 	tests := []struct {
-		name                 string
-		tasks                PipelineTask
-		enableAlphaAPIFields bool
-		enableBetaAPIFields  bool
+		name      string
+		tasks     PipelineTask
+		configMap map[string]string
 	}{{
 		name: "pipeline task - valid taskRef name",
 		tasks: PipelineTask{
@@ -524,37 +523,51 @@ func TestPipelineTask_ValidateRegularTask_Success(t *testing.T) {
 			Name:     "foo",
 			TaskSpec: &EmbeddedTask{TaskSpec: getTaskSpec()},
 		},
+	}, {
+		name: "pipeline task - valid taskSpec with param enum",
+		tasks: PipelineTask{
+			Name: "foo",
+			TaskSpec: &EmbeddedTask{
+				TaskSpec: TaskSpec{
+					Steps: []Step{
+						{
+							Name:  "foo",
+							Image: "bar",
+						},
+					},
+					Params: []ParamSpec{
+						{
+							Name: "param1",
+							Type: ParamTypeString,
+							Enum: []string{"v1", "v2"},
+						},
+					},
+				},
+			},
+		},
+		configMap: map[string]string{"enable-param-enum": "true"},
 	}, {
 		name: "pipeline task - use of resolver with the feature flag set",
 		tasks: PipelineTask{
 			TaskRef: &TaskRef{ResolverRef: ResolverRef{Resolver: "bar"}},
 		},
-		enableBetaAPIFields: true,
+		configMap: map[string]string{"enable-api-field": "beta"},
 	}, {
 		name: "pipeline task - use of resolver with the feature flag set to alpha",
 		tasks: PipelineTask{
 			TaskRef: &TaskRef{ResolverRef: ResolverRef{Resolver: "bar"}},
 		},
-		enableAlphaAPIFields: true,
+		configMap: map[string]string{"enable-api-field": "alpha"},
 	}, {
 		name: "pipeline task - use of resolver params with the feature flag set",
 		tasks: PipelineTask{
 			TaskRef: &TaskRef{ResolverRef: ResolverRef{Resolver: "bar", Params: Params{{}}}},
 		},
-		enableBetaAPIFields: true,
+		configMap: map[string]string{"enable-api-field": "beta"},
 	}}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
-			ctx := context.Background()
-			cfg := &config.Config{
-				FeatureFlags: &config.FeatureFlags{},
-			}
-			if tt.enableAlphaAPIFields {
-				cfg.FeatureFlags.EnableAPIFields = config.AlphaAPIFields
-			} else if tt.enableBetaAPIFields {
-				cfg.FeatureFlags.EnableAPIFields = config.BetaAPIFields
-			}
-			ctx = config.ToContext(ctx, cfg)
+			ctx := cfgtesting.SetFeatureFlags(context.Background(), t, tt.configMap)
 			err := tt.tasks.validateTask(ctx)
 			if err != nil {
 				t.Errorf("PipelineTask.validateTask() returned error for valid pipeline task: %v", err)

pkg/apis/pipeline/v1/pipeline_validation.go

@@ -433,11 +433,12 @@ func validatePipelineTasksWorkspacesUsage(wss []PipelineWorkspaceDeclaration, pt
 
 // ValidatePipelineParameterVariables validates parameters with those specified by each pipeline task,
 // (1) it validates the type of parameter is either string or array (2) parameter default value matches
-// with the type of that param
+// with the type of that param (3) no duplicateion, feature flag and allowed param type when using param enum
 func ValidatePipelineParameterVariables(ctx context.Context, tasks []PipelineTask, params ParamSpecs) (errs *apis.FieldError) {
 	// validates all the types within a slice of ParamSpecs
 	errs = errs.Also(ValidateParameterTypes(ctx, params).ViaField("params"))
 	errs = errs.Also(params.validateNoDuplicateNames())
+	errs = errs.Also(params.validateParamEnums(ctx))
 	for i, task := range tasks {
 		errs = errs.Also(task.Params.validateDuplicateParameters().ViaField("params").ViaIndex(i))
 	}

pkg/apis/pipeline/v1/pipeline_validation_test.go

@@ -1295,9 +1295,10 @@ func TestFinallyTaskResultsToPipelineResults_Failure(t *testing.T) {
 
 func TestValidatePipelineParameterVariables_Success(t *testing.T) {
 	tests := []struct {
-		name   string
-		params []ParamSpec
-		tasks  []PipelineTask
+		name      string
+		params    []ParamSpec
+		tasks     []PipelineTask
+		configMap map[string]string
 	}{{
 		name: "valid string parameter variables",
 		params: []ParamSpec{{
@@ -1312,6 +1313,21 @@ func TestValidatePipelineParameterVariables_Success(t *testing.T) {
 				Name: "a-param", Value: ParamValue{Type: ParamTypeString, StringVal: "$(params.baz) and $(params.foo-is-baz)"},
 			}},
 		}},
+	}, {
+		name: "valid string parameter variables with enum",
+		params: []ParamSpec{{
+			Name: "baz", Type: ParamTypeString, Enum: []string{"v1", "v2"},
+		}, {
+			Name: "foo-is-baz", Type: ParamTypeString,
+		}},
+		tasks: []PipelineTask{{
+			Name:    "bar",
+			TaskRef: &TaskRef{Name: "bar-task"},
+			Params: Params{{
+				Name: "a-param", Value: ParamValue{Type: ParamTypeString, StringVal: "$(params.baz) and $(params.foo-is-baz)"},
+			}},
+		}},
+		configMap: map[string]string{"enable-param-enum": "true"},
 	}, {
 		name: "valid string parameter variables in when expression",
 		params: []ParamSpec{{
@@ -1580,6 +1596,9 @@ func TestValidatePipelineParameterVariables_Success(t *testing.T) {
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
 			ctx := cfgtesting.EnableAlphaAPIFields(context.Background())
+			if tt.configMap != nil {
+				ctx = cfgtesting.SetFeatureFlags(ctx, t, tt.configMap)
+			}
 			err := ValidatePipelineParameterVariables(ctx, tt.tasks, tt.params)
 			if err != nil {
 				t.Errorf("Pipeline.ValidatePipelineParameterVariables() returned error for valid pipeline parameters: %v", err)
@@ -1921,7 +1940,7 @@ func TestValidatePipelineDeclaredParameterUsage_Failure(t *testing.T) {
 		t.Run(tt.name, func(t *testing.T) {
 			err := validatePipelineTaskParameterUsage(tt.tasks, tt.params)
 			if err == nil {
-				t.Errorf("Pipeline.ValidatePipelineParameterVariables() did not return error for invalid pipeline parameters")
+				t.Errorf("Pipeline.validatePipelineTaskParameterUsage() did not return error for invalid pipeline parameters")
 			}
 			if d := cmp.Diff(tt.expectedError.Error(), err.Error(), cmpopts.IgnoreUnexported(apis.FieldError{})); d != "" {
 				t.Errorf("PipelineSpec.Validate() errors diff %s", diff.PrintWantGot(d))
@@ -1936,7 +1955,69 @@ func TestValidatePipelineParameterVariables_Failure(t *testing.T) {
 		params        []ParamSpec
 		tasks         []PipelineTask
 		expectedError apis.FieldError
+		configMap     map[string]string
 	}{{
+		name: "param enum with array type - failure",
+		params: []ParamSpec{{
+			Name: "param1",
+			Type: ParamTypeArray,
+			Enum: []string{"v1", "v2"},
+		}},
+		tasks: []PipelineTask{{
+			Name:    "foo",
+			TaskRef: &TaskRef{Name: "foo-task"},
+		}},
+		configMap: map[string]string{
+			"enable-param-enum": "true",
+		},
+		expectedError: apis.FieldError{
+			Message: `enum can only be set with string type param`,
+			Paths:   []string{"params[param1]"},
+		},
+	}, {
+		name: "param enum with object type - failure",
+		params: []ParamSpec{{
+			Name: "param1",
+			Type: ParamTypeObject,
+			Enum: []string{"v1", "v2"},
+		}},
+		tasks: []PipelineTask{{
+			Name:    "foo",
+			TaskRef: &TaskRef{Name: "foo-task"},
+		}},
+		configMap: map[string]string{
+			"enable-param-enum": "true",
+		},
+		expectedError: apis.FieldError{
+			Message: `enum can only be set with string type param`,
+			Paths:   []string{"params[param1]"},
+		},
+	}, {
+		name: "param enum with duplicate values - failure",
+		params: []ParamSpec{{
+			Name: "param1",
+			Type: ParamTypeString,
+			Enum: []string{"v1", "v1", "v2"},
+		}},
+		configMap: map[string]string{
+			"enable-param-enum": "true",
+		},
+		expectedError: apis.FieldError{
+			Message: `parameter enum value v1 appears more than once`,
+			Paths:   []string{"params[param1]"},
+		},
+	}, {
+		name: "param enum with feature flag disabled - failure",
+		params: []ParamSpec{{
+			Name: "param1",
+			Type: ParamTypeString,
+			Enum: []string{"v1", "v2"},
+		}},
+		expectedError: apis.FieldError{
+			Message: "feature flag `enable-param-enum` should be set to true to use Enum",
+			Paths:   []string{"params[param1]"},
+		},
+	}, {
 		name: "invalid parameter type",
 		params: []ParamSpec{{
 			Name: "foo", Type: "invalidtype",
@@ -2105,6 +2186,10 @@ func TestValidatePipelineParameterVariables_Failure(t *testing.T) {
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
 			ctx := context.Background()
+			if tt.configMap != nil {
+				ctx = cfgtesting.SetFeatureFlags(ctx, t, tt.configMap)
+			}
+
 			err := ValidatePipelineParameterVariables(ctx, tt.tasks, tt.params)
 			if err == nil {
 				t.Errorf("Pipeline.ValidatePipelineParameterVariables() did not return error for invalid pipeline parameters")

pkg/apis/pipeline/v1/swagger.json

@@ -343,6 +343,14 @@
           "description": "Description is a user-facing description of the parameter that may be used to populate a UI.",
           "type": "string"
         },
+        "enum": {
+          "description": "Enum declares a set of allowed param input values for tasks/pipelines that can be validated. If Enum is not set, no input validation is performed for the param.",
+          "type": "array",
+          "items": {
+            "type": "string",
+            "default": ""
+          }
+        },
         "name": {
           "description": "Name declares the name by which a parameter is referenced.",
           "type": "string",

pkg/apis/pipeline/v1/task_validation.go

@@ -435,6 +435,7 @@ func (p ParamSpec) ValidateObjectType(ctx context.Context) *apis.FieldError {
 func ValidateParameterVariables(ctx context.Context, steps []Step, params ParamSpecs) *apis.FieldError {
 	var errs *apis.FieldError
 	errs = errs.Also(params.validateNoDuplicateNames())
+	errs = errs.Also(params.validateParamEnums(ctx))
 	stringParams, arrayParams, objectParams := params.sortByType()
 	stringParameterNames := sets.NewString(stringParams.getNames()...)
 	arrayParameterNames := sets.NewString(arrayParams.getNames()...)