[TEP-0076]Pipeline results support array

This is part of work in TEP-0076.
This commit update the PipelineResult and PipelineRunResult to uspport
array results, meanwhile support the whole array and array indexing
reference from PipelineResult to TaskResult. Before this commit the
pipeline level result only support string.

docs/pipelines.md

@@ -95,7 +95,7 @@ A `Pipeline` definition supports the following fields:
         a `Task` requires.
         - [`from`](#using-the-from-field) - Indicates the data for a [`PipelineResource`](resources.md)
           originates from the output of a previous `Task`.
-      - [`runAfter`](#using-the-runafter-field) - Indicates that a `Task` should execute after one or more other 
+      - [`runAfter`](#using-the-runafter-field) - Indicates that a `Task` should execute after one or more other
         `Tasks` without output linking.
       - [`retries`](#using-the-retries-field) - Specifies the number of times to retry the execution of a `Task` after
         a failure. Does not apply to execution cancellations.
@@ -109,7 +109,7 @@ A `Pipeline` definition supports the following fields:
   - [`results`](#emitting-results-from-a-pipeline) - Specifies the location to which the `Pipeline` emits its execution
     results.
   - [`description`](#adding-a-description) - Holds an informative description of the `Pipeline` object.
-  - [`finally`](#adding-finally-to-the-pipeline) - Specifies one or more `Tasks` to be executed in parallel after 
+  - [`finally`](#adding-finally-to-the-pipeline) - Specifies one or more `Tasks` to be executed in parallel after
     all other tasks have completed.
     - [`name`](#adding-finally-to-the-pipeline) - the name of this `Task` within the context of this `Pipeline`.
     - [`taskRef`](#adding-finally-to-the-pipeline) - a reference to a `Task` definition.
@@ -174,7 +174,7 @@ spec:
           workspace: pipeline-ws1
 ```
 
-For simplicity you can also map the name of the `Workspace` in `PipelineTask` to match with 
+For simplicity you can also map the name of the `Workspace` in `PipelineTask` to match with
 the `Workspace` from the `Pipeline`.
 For example:
 
@@ -191,12 +191,12 @@ spec:
       taskRef:
         name: gen-code # gen-code expects a Workspace named "source"
       workspaces:
-        - name: source # <- mapping workspace name 
+        - name: source # <- mapping workspace name
     - name: commit
       taskRef:
         name: commit # commit expects a Workspace named "source"
       workspaces:
-        - name: source # <- mapping workspace name 
+        - name: source # <- mapping workspace name
       runAfter:
         - gen-code
 ```
@@ -402,7 +402,7 @@ spec:
 `"true"` in the `feature-flags` configmap, see [`install.md`](./install.md#customizing-the-pipelines-controller-behavior)**
 
 You may also specify your `Task` reference using a `Tekton Bundle`. A `Tekton Bundle` is an OCI artifact that
-contains Tekton resources like `Tasks` which can be referenced within a `taskRef`.  
+contains Tekton resources like `Tasks` which can be referenced within a `taskRef`.
 
 There is currently a hard limit of 20 objects in a bundle.
 
@@ -628,7 +628,7 @@ To guard a `Task` and its dependent Tasks:
 
 ##### Cascade `when` expressions to the specific dependent `Tasks`
 
-Pick and choose which specific dependent `Tasks` to guard as well, and cascade the `when` expressions to those `Tasks`. 
+Pick and choose which specific dependent `Tasks` to guard as well, and cascade the `when` expressions to those `Tasks`.
 
 Taking the use case below, a user who wants to guard `manual-approval` and its dependent `Tasks`:
 
@@ -689,12 +689,12 @@ tasks:
       value: $(tasks.manual-approval.results.approver)
   taskRef:
     name: slack-msg
-```  
+```
 
 ##### Compose using Pipelines in Pipelines
 
-Compose a set of `Tasks` as a unit of execution using `Pipelines` in `Pipelines`, which allows for guarding a `Task` and 
-its dependent `Tasks` (as a sub-`Pipeline`) using `when` expressions. 
+Compose a set of `Tasks` as a unit of execution using `Pipelines` in `Pipelines`, which allows for guarding a `Task` and
+its dependent `Tasks` (as a sub-`Pipeline`) using `when` expressions.
 
 **Note:** `Pipelines` in `Pipelines` is an [experimental feature](https://github.com/tektoncd/experimental/tree/main/pipelines-in-pipelines)
 
@@ -742,7 +742,7 @@ tasks:
         value: $(tasks.manual-approval.results.approver)
     taskRef:
       name: slack-msg
-      
+
 ---
 ## main pipeline
 tasks:
@@ -765,12 +765,12 @@ tasks:
 
 When `when` expressions evaluate to `False`, the `Task` will be skipped and:
 - The ordering-dependent `Tasks` will be executed
-- The resource-dependent `Tasks` (and their dependencies) will be skipped because of missing `Results` from the skipped 
-  parent `Task`. When we add support for [default `Results`](https://github.com/tektoncd/community/pull/240), then the 
-  resource-dependent `Tasks` may be executed if the default `Results` from the skipped parent `Task` are specified. In 
+- The resource-dependent `Tasks` (and their dependencies) will be skipped because of missing `Results` from the skipped
+  parent `Task`. When we add support for [default `Results`](https://github.com/tektoncd/community/pull/240), then the
+  resource-dependent `Tasks` may be executed if the default `Results` from the skipped parent `Task` are specified. In
   addition, if a resource-dependent `Task` needs a file from a guarded parent `Task` in a shared `Workspace`, make sure
-  to handle the execution of the child `Task` in case the expected file is missing from the `Workspace` because the 
-  guarded parent `Task` is skipped. 
+  to handle the execution of the child `Task` in case the expected file is missing from the `Workspace` because the
+  guarded parent `Task` is skipped.
 
 On the other hand, the rest of the `Pipeline` will continue executing.
 
@@ -823,12 +823,12 @@ tasks:
     name: slack-msg
 ```
 
-If `manual-approval` is skipped, execution of its dependent `Tasks` (`slack-msg`, `build-image` and `deploy-image`) 
+If `manual-approval` is skipped, execution of its dependent `Tasks` (`slack-msg`, `build-image` and `deploy-image`)
 would be unblocked regardless:
 - `build-image` and `deploy-image` should be executed successfully
 - `slack-msg` will be skipped because it is missing the `approver` `Result` from `manual-approval`
   - dependents of `slack-msg` would have been skipped too if it had any of them
-  - if `manual-approval` specifies a default `approver` `Result`, such as "None", then `slack-msg` would be executed 
+  - if `manual-approval` specifies a default `approver` `Result`, such as "None", then `slack-msg` would be executed
     ([supporting default `Results` is in progress](https://github.com/tektoncd/community/pull/240))
 
 ### Configuring the failure timeout
@@ -944,7 +944,7 @@ when:
 
 For an end-to-end example, see [`Task` `Results` in a `PipelineRun`](../examples/v1beta1/pipelineruns/task_results_example.yaml).
 
-Note that `when` expressions are whitespace-sensitive.  In particular, when producing results intended for inputs to `when` 
+Note that `when` expressions are whitespace-sensitive.  In particular, when producing results intended for inputs to `when`
 expressions that may include newlines at their close (e.g. `cat`, `jq`), you may wish to truncate them.
 
 ```yaml
@@ -985,6 +985,8 @@ results:
 
 For an end-to-end example, see [`Results` in a `PipelineRun`](../examples/v1beta1/pipelineruns/pipelinerun-results.yaml).
 
+Array results is supported as alpha feature, see [`Array Results` in a `PipelineRun`](../examples/v1beta1/pipelineruns/alpha/pipelinerun-array-results.yaml).
+
 A `Pipeline Result` is not emitted if any of the following are true:
 - A `PipelineTask` referenced by the `Pipeline Result` failed. The `PipelineRun` will also
 have failed.
@@ -1009,9 +1011,9 @@ without getting stuck in an infinite loop.
 This is done using:
 - _resource dependencies_:
   - [`from`](#using-the-from-field) clauses on the [`PipelineResources`](resources.md) used by each `Task`
-  - [`results`](#emitting-results-from-a-pipeline) of one `Task` being passed into `params` or `when` expressions of 
+  - [`results`](#emitting-results-from-a-pipeline) of one `Task` being passed into `params` or `when` expressions of
     another
-    
+
 - _ordering dependencies_:
   - [`runAfter`](#using-the-runafter-field) clauses on the corresponding `Tasks`
 
@@ -1197,7 +1199,7 @@ spec:
           value: "someURL"
       matrix:
         - name: slack-channel
-          value: 
+          value:
           - "foo"
           - "bar"
 ```

examples/v1beta1/pipelineruns/alpha/pipeline-array-results.yaml

@@ -0,0 +1,40 @@
+apiVersion: tekton.dev/v1beta1
+kind: PipelineRun
+metadata:
+  name: pipelinerun-array-indexing-results
+spec:
+  pipelineSpec:
+    tasks:
+      - name: task1
+        taskSpec:
+          results:
+            - name: array-results
+              type: array
+              description: The array results
+          steps:
+            - name: write-array
+              image: bash:latest
+              script: |
+                #!/usr/bin/env bash
+                echo -n "[\"1\",\"2\",\"3\"]" | tee $(results.array-results.path)
+      - name: task2
+        taskSpec:
+          results:
+            - name: array-results
+              type: array
+              description: The array results
+          steps:
+            - name: write-array
+              image: bash:latest
+              script: |
+                #!/usr/bin/env bash
+                echo -n "[\"4\",\"5\",\"6\"]" | tee $(results.array-results.path)
+    results:
+      - name: echo-indexing-array-results
+        type: string
+        description: array element
+        value: $(tasks.task1.results.array-results[1])
+      - name: echo-array-results
+        type: array
+        description: whole array
+        value: $(tasks.task2.results.array-results[*])

pkg/apis/pipeline/v1beta1/param_types.go

@@ -228,7 +228,7 @@ func (arrayOrString *ArrayOrString) applyOrCorrect(stringReplacements map[string
 
 	// trim the head "$(" and the tail ")" or "[*])"
 	// i.e. get "params.name" from "$(params.name)" or "$(params.name[*])"
-	trimedStringVal := strings.TrimSuffix(strings.TrimSuffix(strings.TrimPrefix(stringVal, "$("), ")"), "[*]")
+	trimedStringVal := StripStarVarSubExpression(stringVal)
 
 	// if the stringVal is a reference to a string param
 	if _, ok := stringReplacements[trimedStringVal]; ok {
@@ -250,6 +250,11 @@ func (arrayOrString *ArrayOrString) applyOrCorrect(stringReplacements map[string
 	}
 }
 
+// StripStarVarSubExpression strips "$(target[*])"" to get "target"
+func StripStarVarSubExpression(s string) string {
+	return strings.TrimSuffix(strings.TrimSuffix(strings.TrimPrefix(s, "$("), ")"), "[*]")
+}
+
 // NewArrayOrString creates an ArrayOrString of type ParamTypeString or ParamTypeArray, based on
 // how many inputs are given (>1 input will create an array, not string).
 func NewArrayOrString(value string, values ...string) *ArrayOrString {

pkg/apis/pipeline/v1beta1/pipeline_types.go

@@ -123,12 +123,17 @@ type PipelineResult struct {
 	// Name the given name
 	Name string `json:"name"`
 
+	// Type is the user-specified type of the result.
+	// The possible types are 'string', 'array', and 'object', with 'string' as the default.
+	// 'array' and 'object' types are alpha features.
+	Type ResultsType `json:"type,omitempty"`
+
 	// Description is a human-readable description of the result
 	// +optional
 	Description string `json:"description"`
 
 	// Value the expression used to retrieve the value
-	Value string `json:"value"`
+	Value ArrayOrString `json:"value"`
 }
 
 // PipelineTaskMetadata contains the labels or annotations for an EmbeddedTask

pkg/apis/pipeline/v1beta1/pipeline_validation_test.go

@@ -129,7 +129,7 @@ func TestPipeline_Validate_Success(t *testing.T) {
 				Results: []PipelineResult{{
 					Name:        "pipeline-result",
 					Description: "this is my pipeline result",
-					Value:       "$(tasks.my-task.results.my-result)",
+					Value:       *NewArrayOrString("$(tasks.my-task.results.my-result)"),
 				}},
 			},
 		},
@@ -1143,11 +1143,11 @@ func TestValidatePipelineResults_Success(t *testing.T) {
 	results := []PipelineResult{{
 		Name:        "my-pipeline-result",
 		Description: "this is my pipeline result",
-		Value:       "$(tasks.a-task.results.output)",
+		Value:       *NewArrayOrString("$(tasks.a-task.results.output)"),
 	}, {
 		Name:        "my-pipeline-object-result",
 		Description: "this is my pipeline result",
-		Value:       "$(tasks.a-task.results.gitrepo.commit)",
+		Value:       *NewArrayOrString("$(tasks.a-task.results.gitrepo.commit)"),
 	}}
 	if err := validatePipelineResults(results); err != nil {
 		t.Errorf("Pipeline.validatePipelineResults() returned error for valid pipeline: %s: %v", desc, err)
@@ -1164,7 +1164,7 @@ func TestValidatePipelineResults_Failure(t *testing.T) {
 		results: []PipelineResult{{
 			Name:        "my-pipeline-result",
 			Description: "this is my pipeline result",
-			Value:       "$(tasks.a-task.results.output.key1.extra)",
+			Value:       *NewArrayOrString("$(tasks.a-task.results.output.key1.extra)"),
 		}},
 		expectedError: apis.FieldError{
 			Message: `invalid value: expected all of the expressions [tasks.a-task.results.output.key1.extra] to be result expressions but only [] were`,
@@ -1175,7 +1175,7 @@ func TestValidatePipelineResults_Failure(t *testing.T) {
 		results: []PipelineResult{{
 			Name:        "my-pipeline-result",
 			Description: "this is my pipeline result",
-			Value:       "foo.bar",
+			Value:       *NewArrayOrString("foo.bar"),
 		}},
 		expectedError: apis.FieldError{
 			Message: `invalid value: expected pipeline results to be task result expressions but no expressions were found`,
@@ -1186,7 +1186,7 @@ func TestValidatePipelineResults_Failure(t *testing.T) {
 		results: []PipelineResult{{
 			Name:        "my-pipeline-result",
 			Description: "this is my pipeline result",
-			Value:       "$(foo.bar)",
+			Value:       *NewArrayOrString("$(foo.bar)"),
 		}},
 		expectedError: apis.FieldError{
 			Message: `invalid value: expected pipeline results to be task result expressions but an invalid expressions was found`,

pkg/apis/pipeline/v1beta1/pipelinerun_types.go

@@ -478,7 +478,7 @@ type PipelineRunResult struct {
 	Name string `json:"name"`
 
 	// Value is the result returned from the execution of this PipelineRun
-	Value string `json:"value"`
+	Value ArrayOrString `json:"value"`
 }
 
 // PipelineRunTaskRunStatus contains the name of the PipelineTask for this TaskRun and the TaskRun's Status