[TEP-0104] Update Pod with Task-level Requirements

The task-level compute resource requirements will be applied on the containers created
by the Pod.

docs/compute-resources.md

@@ -45,7 +45,7 @@ Therefore, the pod will have no effective CPU limit.
 ## Task-level Compute Resources Configuration
 
 **([alpha only](https://github.com/tektoncd/pipeline/blob/main/docs/install.md#alpha-features))**
-(This feature is under development and not functional yet. Stay tuned!)
+(This alpha feature is implemented)
 
 Tekton allows users to specify resource requirements of [`Steps`](./tasks.md#defining-steps),
 which run sequentially. However, the pod's effective resource requirements are still the
@@ -63,7 +63,9 @@ Each of these details is explained in more depth below.
 Some points to note:
 
 - Task-level resource requests and limits do not apply to sidecars which can be configured separately.
-- Users may not configure the Task-level and Step-level resource requirements (requests/limits)  simultaneously.
+- If only limits are configured in task-level, it will be applied as the task-level requests.
+- Resource requirements configured in `Step` or `StepTemplate` of the referenced `Task` will be overridden by the task-level requirements.
+- `TaskRun` configured with both `StepOverrides` and task-level requirements will be rejected.
 
 ### Configure Task-level Compute Resources
 
@@ -84,7 +86,7 @@ spec:
       cpu: 2
 ```
 
-The following TaskRun will be rejected, because it configures both step-level and task-level compute resource requirements:
+The following TaskRun will be rejected, because it configures both stepOverrides and task-level compute resource requirements:
 
 ```yaml
 kind: TaskRun

pkg/internal/computeresources/tasklevel/tasklevel.go

@@ -0,0 +1,57 @@
+/*
+Copyright 2020 The Tekton Authors
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package tasklevel
+
+import (
+	"github.com/tektoncd/pipeline/pkg/apis/pipeline/v1beta1"
+	corev1 "k8s.io/api/core/v1"
+	"k8s.io/apimachinery/pkg/api/resource"
+)
+
+// ApplyTaskLevelComputeResources applies the task-level compute resource requirements to each Step.
+func ApplyTaskLevelComputeResources(steps []v1beta1.Step, computeResources *corev1.ResourceRequirements) {
+	if computeResources == nil {
+		return
+	}
+	if computeResources.Requests == nil && computeResources.Limits == nil {
+		return
+	}
+	averageRequests := computeAverageRequests(computeResources.Requests, len(steps))
+	averageLimits := computeAverageRequests(computeResources.Limits, len(steps))
+	for i := range steps {
+		// if no requests are specified in step or task level, the limits are used to avoid
+		// unnecessary higher requests by Kubernetes default behavior.
+		if steps[i].Resources.Requests == nil && computeResources.Requests == nil {
+			steps[i].Resources.Requests = averageLimits
+		} else {
+			steps[i].Resources.Requests = averageRequests
+		}
+		steps[i].Resources.Limits = computeResources.Limits
+	}
+}
+
+// computeAverageRequests computes the average of the requests of all the steps.
+func computeAverageRequests(requests corev1.ResourceList, steps int) corev1.ResourceList {
+	if len(requests) == 0 || steps == 0 {
+		return nil
+	}
+	averageRequests := corev1.ResourceList{}
+	for k, v := range requests {
+		averageRequests[k] = *resource.NewMilliQuantity(v.MilliValue()/int64(steps), requests[k].Format)
+	}
+	return averageRequests
+}

pkg/internal/computeresources/tasklevel/tasklevel_test.go

@@ -0,0 +1,206 @@
+/*
+Copyright 2019 The Tekton Authors
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package tasklevel_test
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/google/go-cmp/cmp"
+	"github.com/tektoncd/pipeline/pkg/apis/pipeline/v1beta1"
+	"github.com/tektoncd/pipeline/pkg/internal/computeresources/tasklevel"
+	"github.com/tektoncd/pipeline/test/diff"
+	corev1 "k8s.io/api/core/v1"
+	"k8s.io/apimachinery/pkg/api/resource"
+)
+
+func TestApplyTaskLevelResourceRequirements(t *testing.T) {
+	testcases := []struct {
+		desc                     string
+		Steps                    []v1beta1.Step
+		ComputeResources         corev1.ResourceRequirements
+		expectedComputeResources []corev1.ResourceRequirements
+	}{{
+		desc: "only with requests",
+		Steps: []v1beta1.Step{{
+			Name:    "1st-step",
+			Image:   "image",
+			Command: []string{"cmd"},
+		}, {
+			Name:    "2nd-step",
+			Image:   "image",
+			Command: []string{"cmd"},
+		}},
+		ComputeResources: corev1.ResourceRequirements{
+			Requests: corev1.ResourceList{corev1.ResourceCPU: resource.MustParse("2")},
+		},
+		expectedComputeResources: []corev1.ResourceRequirements{{
+			Requests: corev1.ResourceList{corev1.ResourceCPU: resource.MustParse("1")},
+		}, {
+			Requests: corev1.ResourceList{corev1.ResourceCPU: resource.MustParse("1")},
+		}},
+	}, {
+		desc: "only with limits",
+		Steps: []v1beta1.Step{{
+			Name:    "1st-step",
+			Image:   "image",
+			Command: []string{"cmd"},
+		}, {
+			Name:    "2nd-step",
+			Image:   "image",
+			Command: []string{"cmd"},
+		}},
+		ComputeResources: corev1.ResourceRequirements{
+			Limits: corev1.ResourceList{corev1.ResourceCPU: resource.MustParse("500m")},
+		},
+		expectedComputeResources: []corev1.ResourceRequirements{{
+			Requests: corev1.ResourceList{corev1.ResourceCPU: resource.MustParse("250m")},
+			Limits:   corev1.ResourceList{corev1.ResourceCPU: resource.MustParse("500m")},
+		}, {
+			Requests: corev1.ResourceList{corev1.ResourceCPU: resource.MustParse("250m")},
+			Limits:   corev1.ResourceList{corev1.ResourceCPU: resource.MustParse("500m")},
+		}},
+	}, {
+		desc: "both with requests and limits",
+		Steps: []v1beta1.Step{{
+			Name:    "1st-step",
+			Image:   "image",
+			Command: []string{"cmd"},
+		}, {
+			Name:    "2nd-step",
+			Image:   "image",
+			Command: []string{"cmd"},
+		}},
+		ComputeResources: corev1.ResourceRequirements{
+			Requests: corev1.ResourceList{corev1.ResourceCPU: resource.MustParse("1")},
+			Limits:   corev1.ResourceList{corev1.ResourceCPU: resource.MustParse("2")},
+		},
+		expectedComputeResources: []corev1.ResourceRequirements{{
+			Requests: corev1.ResourceList{corev1.ResourceCPU: resource.MustParse("500m")},
+			Limits:   corev1.ResourceList{corev1.ResourceCPU: resource.MustParse("2")},
+		}, {
+			Requests: corev1.ResourceList{corev1.ResourceCPU: resource.MustParse("500m")},
+			Limits:   corev1.ResourceList{corev1.ResourceCPU: resource.MustParse("2")},
+		}},
+	}, {
+		desc: "steps with compute resources are overridden by task-level compute resources",
+		Steps: []v1beta1.Step{{
+			Name:    "1st-step",
+			Image:   "image",
+			Command: []string{"cmd"},
+			Resources: corev1.ResourceRequirements{
+				Requests: corev1.ResourceList{corev1.ResourceCPU: resource.MustParse("100m")},
+				Limits:   corev1.ResourceList{corev1.ResourceCPU: resource.MustParse("1")},
+			},
+		}, {
+			Name:    "2nd-step",
+			Image:   "image",
+			Command: []string{"cmd"},
+			Resources: corev1.ResourceRequirements{
+				Requests: corev1.ResourceList{corev1.ResourceCPU: resource.MustParse("200m")},
+				Limits:   corev1.ResourceList{corev1.ResourceCPU: resource.MustParse("1")},
+			},
+		}},
+		ComputeResources: corev1.ResourceRequirements{
+			Requests: corev1.ResourceList{corev1.ResourceCPU: resource.MustParse("1")},
+			Limits:   corev1.ResourceList{corev1.ResourceCPU: resource.MustParse("2")},
+		},
+		expectedComputeResources: []corev1.ResourceRequirements{{
+			Requests: corev1.ResourceList{corev1.ResourceCPU: resource.MustParse("500m")},
+			Limits:   corev1.ResourceList{corev1.ResourceCPU: resource.MustParse("2")},
+		}, {
+			Requests: corev1.ResourceList{corev1.ResourceCPU: resource.MustParse("500m")},
+			Limits:   corev1.ResourceList{corev1.ResourceCPU: resource.MustParse("2")},
+		}},
+	}, {
+		desc: "steps with partial compute resources are overridden by task-level compute resources",
+		Steps: []v1beta1.Step{{
+			Name:    "1st-step",
+			Image:   "image",
+			Command: []string{"cmd"},
+			Resources: corev1.ResourceRequirements{
+				Requests: corev1.ResourceList{corev1.ResourceCPU: resource.MustParse("100m")},
+				Limits:   corev1.ResourceList{corev1.ResourceCPU: resource.MustParse("1")},
+			},
+		}, {
+			Name:    "2nd-step",
+			Image:   "image",
+			Command: []string{"cmd"},
+		}},
+		ComputeResources: corev1.ResourceRequirements{
+			Requests: corev1.ResourceList{corev1.ResourceCPU: resource.MustParse("1")},
+			Limits:   corev1.ResourceList{corev1.ResourceCPU: resource.MustParse("2")},
+		},
+		expectedComputeResources: []corev1.ResourceRequirements{{
+			Requests: corev1.ResourceList{corev1.ResourceCPU: resource.MustParse("500m")},
+			Limits:   corev1.ResourceList{corev1.ResourceCPU: resource.MustParse("2")},
+		}, {
+			Requests: corev1.ResourceList{corev1.ResourceCPU: resource.MustParse("500m")},
+			Limits:   corev1.ResourceList{corev1.ResourceCPU: resource.MustParse("2")},
+		}},
+	}, {
+		desc: "steps with compute resources are preserved, if there are no task-level compute resources",
+		Steps: []v1beta1.Step{{
+			Name:    "1st-step",
+			Image:   "image",
+			Command: []string{"cmd"},
+			Resources: corev1.ResourceRequirements{
+				Requests: corev1.ResourceList{corev1.ResourceCPU: resource.MustParse("100m")},
+				Limits:   corev1.ResourceList{corev1.ResourceCPU: resource.MustParse("1")},
+			},
+		}, {
+			Name:    "2nd-step",
+			Image:   "image",
+			Command: []string{"cmd"},
+			Resources: corev1.ResourceRequirements{
+				Requests: corev1.ResourceList{corev1.ResourceCPU: resource.MustParse("200m")},
+				Limits:   corev1.ResourceList{corev1.ResourceCPU: resource.MustParse("1")},
+			},
+		}},
+		ComputeResources: corev1.ResourceRequirements{},
+		expectedComputeResources: []corev1.ResourceRequirements{{
+			Requests: corev1.ResourceList{corev1.ResourceCPU: resource.MustParse("100m")},
+			Limits:   corev1.ResourceList{corev1.ResourceCPU: resource.MustParse("1")},
+		}, {
+			Requests: corev1.ResourceList{corev1.ResourceCPU: resource.MustParse("200m")},
+			Limits:   corev1.ResourceList{corev1.ResourceCPU: resource.MustParse("1")},
+		}},
+	}}
+
+	for _, tc := range testcases {
+		t.Run(tc.desc, func(t *testing.T) {
+			tasklevel.ApplyTaskLevelComputeResources(tc.Steps, &tc.ComputeResources)
+
+			if err := verifyTaskLevelComputeResources(tc.Steps, tc.expectedComputeResources); err != nil {
+				t.Errorf("verifyTaskLevelComputeResources: %v", err)
+			}
+		})
+	}
+}
+
+// verifyTaskLevelComputeResources verifies that the given TaskRun's containers have the expected compute resources.
+func verifyTaskLevelComputeResources(steps []v1beta1.Step, expectedComputeResources []corev1.ResourceRequirements) error {
+	if len(expectedComputeResources) != len(steps) {
+		return fmt.Errorf("expected %d compute resource requirements, got %d", len(expectedComputeResources), len(steps))
+	}
+	for id, step := range steps {
+		if d := cmp.Diff(expectedComputeResources[id], step.Resources); d != "" {
+			return fmt.Errorf("container \"#%d\" resource requirements don't match %s", id, diff.PrintWantGot(d))
+		}
+	}
+	return nil
+}

pkg/pod/pod.go

@@ -28,6 +28,7 @@ import (
 	"github.com/tektoncd/pipeline/pkg/apis/pipeline"
 	"github.com/tektoncd/pipeline/pkg/apis/pipeline/pod"
 	"github.com/tektoncd/pipeline/pkg/apis/pipeline/v1beta1"
+	"github.com/tektoncd/pipeline/pkg/internal/computeresources/tasklevel"
 	"github.com/tektoncd/pipeline/pkg/names"
 	corev1 "k8s.io/api/core/v1"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
@@ -143,6 +144,9 @@ func (b *Builder) Build(ctx context.Context, taskRun *v1beta1.TaskRun, taskSpec
 	if err != nil {
 		return nil, err
 	}
+	if alphaAPIEnabled && taskRun.Spec.ComputeResources != nil {
+		tasklevel.ApplyTaskLevelComputeResources(steps, taskRun.Spec.ComputeResources)
+	}
 	sidecars, err := v1beta1.MergeSidecarsWithOverrides(taskSpec.Sidecars, taskRun.Spec.SidecarOverrides)
 	if err != nil {
 		return nil, err