[TEP-0133]: Configure Default resolver

This commit introduces a new `default-resolver-type` field to the `config-defaults` ConfigMap, which configures the default resolver type to be used when the `resolver` is not explicitly provided in the input.
Supporting the default resolver type improves simplicity at the authoring time. More details can be found in [TEP-0113: Conifgure Default Resolver].

/kind feature

[TEP-0113: Conifgure Default Resolver]: https://github.com/tektoncd/community/blob/main/teps/0133-configure-default-resolver.md

config/config-defaults.yaml

@@ -82,3 +82,7 @@ data:
     # default-forbidden-env contains comma seperated environment variables that cannot be
     # overridden by podTemplate.
     default-forbidden-env:
+
+    # default-resolver-type contains the default resolver type to be used in the cluster,
+    # no default-resolver-type is specified by default
+    default-resolver-type:

docs/additional-configs.md

@@ -270,7 +270,7 @@ _In the above example the environment variable `TEST_TEKTON` will not be overrid
 
 ## Customizing basic execution parameters
 
-You can specify your own values that replace the default service account (`ServiceAccount`), timeout (`Timeout`), and Pod template (`PodTemplate`) values used by Tekton Pipelines in `TaskRun` and `PipelineRun` definitions. To do so, modify the ConfigMap `config-defaults` with your desired values.
+You can specify your own values that replace the default service account (`ServiceAccount`), timeout (`Timeout`), resolver (`Resolver`), and Pod template (`PodTemplate`) values used by Tekton Pipelines in `TaskRun` and `PipelineRun` definitions. To do so, modify the ConfigMap `config-defaults` with your desired values.
 
 The example below customizes the following:
 
@@ -279,9 +279,10 @@ The example below customizes the following:
 - the default `app.kubernetes.io/managed-by` label is applied to all Pods created to execute `TaskRuns`.
 - the default Pod template to include a node selector to select the node where the Pod will be scheduled by default. A list of supported fields is available [here](https://github.com/tektoncd/pipeline/blob/main/docs/podtemplates.md#supported-fields).
   For more information, see [`PodTemplate` in `TaskRuns`](./taskruns.md#specifying-a-pod-template) or [`PodTemplate` in `PipelineRuns`](./pipelineruns.md#specifying-a-pod-template).
-- the default `Workspace` configuration can be set for any `Workspaces` that a Task declares but that a TaskRun does not explicitly provide
+- the default `Workspace` configuration can be set for any `Workspaces` that a Task declares but that a TaskRun does not explicitly provide.
 - the default maximum combinations of `Parameters` in a `Matrix` that can be used to fan out a `PipelineTask`. For
 more information, see [`Matrix`](matrix.md).
+- the default resolver type to `git`.
 
 ```yaml
 apiVersion: v1
@@ -298,6 +299,7 @@ data:
   default-task-run-workspace-binding: |
     emptyDir: {}
   default-max-matrix-combinations-count: "1024"
+  default-resolver-type: "git"
 ```
 
 **Note:** The `_example` key in the provided [config-defaults.yaml](./../config/config-defaults.yaml)
@@ -411,6 +413,7 @@ Features currently in "alpha" are:
 | [Trusted Resources](./trusted-resources.md)                                                         | [TEP-0091](https://github.com/tektoncd/community/blob/main/teps/0091-trusted-resources.md)                                 | N/A                                                                  | `resource-verification-mode`  |
 | [`Provenance` field in Status](pipeline-api.md#provenance)                                          | [issue#5550](https://github.com/tektoncd/pipeline/issues/5550)                                                             | N/A                                                                  | `enable-provenance-in-status` |
 | [Larger Results via Sidecar Logs](#enabling-larger-results-using-sidecar-logs)                      | [TEP-0127](https://github.com/tektoncd/community/blob/main/teps/0127-larger-results-via-sidecar-logs.md)                   | [v0.43.0](https://github.com/tektoncd/pipeline/releases/tag/v0.43.0) | `results-from`                |
+| [Configure Default Resolver](./resolution.md#configuring-built-in-resolvers)                        | [TEP-0133](https://github.com/tektoncd/community/blob/main/teps/0133-configure-default-resolver.md)                        | N/A                                 |                                |
 
 ### Beta Features
 

docs/resolution.md

@@ -21,6 +21,8 @@ For new users getting started with Tekton Pipeline remote resolution, check out
 These resolvers are enabled by setting the appropriate feature flag in the `resolvers-feature-flags`
 ConfigMap in the `tekton-pipelines-resolvers` namespace. See the [section in install.md](install.md#configuring-built-in-remote-task-and-pipeline-resolution) for details.
 
+The default resolver type can be configured by the `default-resolver-type` field in the `config-defaults` ConfigMap (`alpha` feature). See [additional-configs.md](./additional-configs.md) for details.
+
 ## Developer Howto: Writing a Resolver From Scratch
 
 For a developer getting started with writing a new Resolver, see

pkg/apis/config/default.go

@@ -44,6 +44,8 @@ const (
 	DefaultCloudEventSinkValue = ""
 	// DefaultMaxMatrixCombinationsCount is used when no max matrix combinations count is specified.
 	DefaultMaxMatrixCombinationsCount = 256
+	// DefaultResolverTypeValue is used when no default resolver type is specified
+	DefaultResolverTypeValue = ""
 
 	defaultTimeoutMinutesKey             = "default-timeout-minutes"
 	defaultServiceAccountKey             = "default-service-account"
@@ -54,6 +56,7 @@ const (
 	defaultTaskRunWorkspaceBinding       = "default-task-run-workspace-binding"
 	defaultMaxMatrixCombinationsCountKey = "default-max-matrix-combinations-count"
 	defaultForbiddenEnv                  = "default-forbidden-env"
+	defaultResolverTypeKey               = "default-resolver-type"
 )
 
 // Defaults holds the default configurations
@@ -68,6 +71,7 @@ type Defaults struct {
 	DefaultTaskRunWorkspaceBinding    string
 	DefaultMaxMatrixCombinationsCount int
 	DefaultForbiddenEnv               []string
+	DefaultResolverType               string
 }
 
 // GetDefaultsConfigName returns the name of the configmap containing all
@@ -97,6 +101,7 @@ func (cfg *Defaults) Equals(other *Defaults) bool {
 		other.DefaultCloudEventsSink == cfg.DefaultCloudEventsSink &&
 		other.DefaultTaskRunWorkspaceBinding == cfg.DefaultTaskRunWorkspaceBinding &&
 		other.DefaultMaxMatrixCombinationsCount == cfg.DefaultMaxMatrixCombinationsCount &&
+		other.DefaultResolverType == cfg.DefaultResolverType &&
 		reflect.DeepEqual(other.DefaultForbiddenEnv, cfg.DefaultForbiddenEnv)
 }
 
@@ -108,6 +113,7 @@ func NewDefaultsFromMap(cfgMap map[string]string) (*Defaults, error) {
 		DefaultManagedByLabelValue:        DefaultManagedByLabelValue,
 		DefaultCloudEventsSink:            DefaultCloudEventSinkValue,
 		DefaultMaxMatrixCombinationsCount: DefaultMaxMatrixCombinationsCount,
+		DefaultResolverType:               DefaultResolverTypeValue,
 	}
 
 	if defaultTimeoutMin, ok := cfgMap[defaultTimeoutMinutesKey]; ok {
@@ -166,6 +172,10 @@ func NewDefaultsFromMap(cfgMap map[string]string) (*Defaults, error) {
 		tc.DefaultForbiddenEnv = tmpString.List()
 	}
 
+	if defaultResolverType, ok := cfgMap[defaultResolverTypeKey]; ok {
+		tc.DefaultResolverType = defaultResolverType
+	}
+
 	return &tc, nil
 }
 

pkg/apis/config/testing/defaults.go

@@ -0,0 +1,23 @@
+package testing
+
+import (
+	"context"
+	"testing"
+
+	"github.com/tektoncd/pipeline/pkg/apis/config"
+	corev1 "k8s.io/api/core/v1"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	logtesting "knative.dev/pkg/logging/testing"
+)
+
+// SetDefaults sets the default ConfigMap values in an existing context (for use in testing)
+func SetDefaults(ctx context.Context, data map[string]string, t *testing.T) context.Context {
+	s := config.NewStore(logtesting.TestLogger(t))
+	s.OnConfigChanged(&corev1.ConfigMap{
+		ObjectMeta: metav1.ObjectMeta{
+			Name: config.GetDefaultsConfigName(),
+		},
+		Data: data,
+	})
+	return s.ToContext(ctx)
+}

pkg/apis/pipeline/v1/pipeline_defaults.go

@@ -19,6 +19,7 @@ package v1
 import (
 	"context"
 
+	"github.com/tektoncd/pipeline/pkg/apis/config"
 	"knative.dev/pkg/apis"
 )
 
@@ -31,6 +32,7 @@ func (p *Pipeline) SetDefaults(ctx context.Context) {
 
 // SetDefaults sets default values for the PipelineSpec's Params, Tasks, and Finally
 func (ps *PipelineSpec) SetDefaults(ctx context.Context) {
+	cfg := config.FromContextOrDefaults(ctx)
 	for i := range ps.Params {
 		ps.Params[i].SetDefaults(ctx)
 	}
@@ -40,6 +42,9 @@ func (ps *PipelineSpec) SetDefaults(ctx context.Context) {
 			if pt.TaskRef.Kind == "" {
 				pt.TaskRef.Kind = NamespacedTaskKind
 			}
+			if pt.TaskRef.Name == "" && pt.TaskRef.Resolver == "" {
+				pt.TaskRef.Resolver = ResolverName(cfg.Defaults.DefaultResolverType)
+			}
 		}
 		if pt.TaskSpec != nil {
 			pt.TaskSpec.SetDefaults(ctx)

pkg/apis/pipeline/v1/pipeline_defaults_test.go

@@ -21,6 +21,7 @@ import (
 	"testing"
 
 	"github.com/google/go-cmp/cmp"
+	dfttesting "github.com/tektoncd/pipeline/pkg/apis/config/testing"
 	v1 "github.com/tektoncd/pipeline/pkg/apis/pipeline/v1"
 	"github.com/tektoncd/pipeline/test/diff"
 )
@@ -37,9 +38,10 @@ func TestPipeline_SetDefaults(t *testing.T) {
 
 func TestPipelineSpec_SetDefaults(t *testing.T) {
 	cases := []struct {
-		desc string
-		ps   *v1.PipelineSpec
-		want *v1.PipelineSpec
+		desc     string
+		ps       *v1.PipelineSpec
+		want     *v1.PipelineSpec
+		defaults map[string]string
 	}{{
 		desc: "empty pipelineSpec must not change after setting defaults",
 		ps:   &v1.PipelineSpec{},
@@ -120,6 +122,54 @@ func TestPipelineSpec_SetDefaults(t *testing.T) {
 				},
 			}},
 		},
+	}, {
+		desc: "pipeline task with taskRef - with default resolver",
+		ps: &v1.PipelineSpec{
+			Tasks: []v1.PipelineTask{{
+				Name:    "foo",
+				TaskRef: &v1.TaskRef{},
+			}},
+		},
+		want: &v1.PipelineSpec{
+			Tasks: []v1.PipelineTask{{
+				Name: "foo",
+				TaskRef: &v1.TaskRef{
+					Kind: v1.NamespacedTaskKind,
+					ResolverRef: v1.ResolverRef{
+						Resolver: "git",
+					},
+				},
+			}},
+		},
+		defaults: map[string]string{
+			"default-resolver-type": "git",
+		},
+	}, {
+		desc: "pipeline task with taskRef - user-provided resolver overwrites default resolver",
+		ps: &v1.PipelineSpec{
+			Tasks: []v1.PipelineTask{{
+				Name: "foo",
+				TaskRef: &v1.TaskRef{
+					ResolverRef: v1.ResolverRef{
+						Resolver: "custom resolver",
+					},
+				},
+			}},
+		},
+		want: &v1.PipelineSpec{
+			Tasks: []v1.PipelineTask{{
+				Name: "foo",
+				TaskRef: &v1.TaskRef{
+					Kind: v1.NamespacedTaskKind,
+					ResolverRef: v1.ResolverRef{
+						Resolver: "custom resolver",
+					},
+				},
+			}},
+		},
+		defaults: map[string]string{
+			"default-resolver-type": "git",
+		},
 	}, {
 		desc: "final pipeline task with taskSpec - default param type must be " + string(v1.ParamTypeString),
 		ps: &v1.PipelineSpec{
@@ -149,6 +199,9 @@ func TestPipelineSpec_SetDefaults(t *testing.T) {
 	for _, tc := range cases {
 		t.Run(tc.desc, func(t *testing.T) {
 			ctx := context.Background()
+			if len(tc.defaults) > 0 {
+				ctx = dfttesting.SetDefaults(context.Background(), tc.defaults, t)
+			}
 			tc.ps.SetDefaults(ctx)
 			if d := cmp.Diff(tc.want, tc.ps); d != "" {
 				t.Errorf("Mismatch of pipelineSpec after setting defaults: %s", diff.PrintWantGot(d))

pkg/apis/pipeline/v1/taskrun_defaults.go

@@ -50,8 +50,13 @@ func (tr *TaskRun) SetDefaults(ctx context.Context) {
 // SetDefaults implements apis.Defaultable
 func (trs *TaskRunSpec) SetDefaults(ctx context.Context) {
 	cfg := config.FromContextOrDefaults(ctx)
-	if trs.TaskRef != nil && trs.TaskRef.Kind == "" {
-		trs.TaskRef.Kind = NamespacedTaskKind
+	if trs.TaskRef != nil {
+		if trs.TaskRef.Kind == "" {
+			trs.TaskRef.Kind = NamespacedTaskKind
+		}
+		if trs.TaskRef.Name == "" && trs.TaskRef.Resolver == "" {
+			trs.TaskRef.Resolver = ResolverName(cfg.Defaults.DefaultResolverType)
+		}
 	}
 
 	if trs.Timeout == nil {