taskref.go

/*
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 resources

import (
	"context"
	"errors"
	"fmt"
	"strings"

	"github.com/google/go-containerregistry/pkg/authn/k8schain"
	"github.com/tektoncd/pipeline/pkg/apis/config"
	"github.com/tektoncd/pipeline/pkg/apis/pipeline/v1alpha1"
	"github.com/tektoncd/pipeline/pkg/apis/pipeline/v1beta1"
	clientset "github.com/tektoncd/pipeline/pkg/client/clientset/versioned"
	"github.com/tektoncd/pipeline/pkg/remote"
	"github.com/tektoncd/pipeline/pkg/remote/oci"
	"github.com/tektoncd/pipeline/pkg/remote/resolution"
	remoteresource "github.com/tektoncd/pipeline/pkg/resolution/resource"
	"github.com/tektoncd/pipeline/pkg/trustedresources"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/apimachinery/pkg/runtime"
	"k8s.io/client-go/kubernetes"
	"knative.dev/pkg/kmeta"
	"knative.dev/pkg/logging"
)

// This error is defined in etcd at
// https://github.com/etcd-io/etcd/blob/5b226e0abf4100253c94bb71f47d6815877ed5a2/server/etcdserver/errors.go#L30
// TODO: If/when https://github.com/kubernetes/kubernetes/issues/106491 is addressed,
// we should stop relying on a hardcoded string.
var errEtcdLeaderChange = "etcdserver: leader changed"

// GetTaskKind returns the referenced Task kind (Task, ClusterTask, ...) if the TaskRun is using TaskRef.
func GetTaskKind(taskrun *v1beta1.TaskRun) v1beta1.TaskKind {
	kind := v1beta1.NamespacedTaskKind
	if taskrun.Spec.TaskRef != nil && taskrun.Spec.TaskRef.Kind != "" {
		kind = taskrun.Spec.TaskRef.Kind
	}
	return kind
}

// GetTaskFuncFromTaskRun is a factory function that will use the given TaskRef as context to return a valid GetTask function. It
// also requires a kubeclient, tektonclient, namespace, and service account in case it needs to find that task in
// cluster or authorize against an external repositroy. It will figure out whether it needs to look in the cluster or in
// a remote image to fetch the  reference. It will also return the "kind" of the task being referenced.
func GetTaskFuncFromTaskRun(ctx context.Context, k8s kubernetes.Interface, tekton clientset.Interface, requester remoteresource.Requester, taskrun *v1beta1.TaskRun, verificationpolicies []*v1alpha1.VerificationPolicy) GetTask {
	// if the spec is already in the status, do not try to fetch it again, just use it as source of truth.
	// Same for the Source field in the Status.Provenance.
	if taskrun.Status.TaskSpec != nil {
		return func(_ context.Context, name string) (v1beta1.TaskObject, *v1beta1.ConfigSource, error) {
			var configsource *v1beta1.ConfigSource
			if taskrun.Status.Provenance != nil {
				configsource = taskrun.Status.Provenance.ConfigSource
			}
			return &v1beta1.Task{
				ObjectMeta: metav1.ObjectMeta{
					Name:      name,
					Namespace: taskrun.Namespace,
				},
				Spec: *taskrun.Status.TaskSpec,
			}, configsource, nil
		}
	}
	return GetVerifiedTaskFunc(ctx, k8s, tekton, requester, taskrun, taskrun.Spec.TaskRef, taskrun.Name, taskrun.Namespace, taskrun.Spec.ServiceAccountName, verificationpolicies)
}

// GetVerifiedTaskFunc is a wrapper of GetTaskFunc and return the function to
// verify the task if resource-verification-mode is not "skip"
func GetVerifiedTaskFunc(ctx context.Context, k8s kubernetes.Interface, tekton clientset.Interface, requester remoteresource.Requester,
	owner kmeta.OwnerRefable, taskref *v1beta1.TaskRef, trName string, namespace, saName string, verificationpolicies []*v1alpha1.VerificationPolicy) GetTask {
	get := GetTaskFunc(ctx, k8s, tekton, requester, owner, taskref, trName, namespace, saName)

	return func(context.Context, string) (v1beta1.TaskObject, *v1beta1.ConfigSource, error) {
		t, s, err := get(ctx, taskref.Name)
		if err != nil {
			return nil, nil, fmt.Errorf("failed to get task: %w", err)
		}
		var source string
		if s != nil {
			source = s.URI
		}
		logger := logging.FromContext(ctx)
		if config.CheckEnforceResourceVerificationMode(ctx) || config.CheckWarnResourceVerificationMode(ctx) {
			if err := trustedresources.VerifyTask(ctx, t, k8s, source, verificationpolicies); err != nil {
				if config.CheckEnforceResourceVerificationMode(ctx) {
					logger.Errorf("GetVerifiedTaskFunc failed: %v", err)
					return nil, nil, fmt.Errorf("GetVerifiedTaskFunc failed: %w: %v", trustedresources.ErrorResourceVerificationFailed, err)
				}
				logger.Warnf("GetVerifiedTaskFunc failed: %v", err)
				return t, s, nil
			}
		}
		return t, s, nil
	}
}

// GetTaskFunc is a factory function that will use the given TaskRef as context to return a valid GetTask function. It
// also requires a kubeclient, tektonclient, namespace, and service account in case it needs to find that task in
// cluster or authorize against an external repositroy. It will figure out whether it needs to look in the cluster or in
// a remote image to fetch the  reference. It will also return the "kind" of the task being referenced.
func GetTaskFunc(ctx context.Context, k8s kubernetes.Interface, tekton clientset.Interface, requester remoteresource.Requester,
	owner kmeta.OwnerRefable, tr *v1beta1.TaskRef, trName string, namespace, saName string) GetTask {
	cfg := config.FromContextOrDefaults(ctx)
	kind := v1beta1.NamespacedTaskKind
	if tr != nil && tr.Kind != "" {
		kind = tr.Kind
	}

	switch {
	case cfg.FeatureFlags.EnableTektonOCIBundles && tr != nil && tr.Bundle != "":
		// Return an inline function that implements GetTask by calling Resolver.Get with the specified task type and
		// casting it to a TaskObject.
		return func(ctx context.Context, name string) (v1beta1.TaskObject, *v1beta1.ConfigSource, error) {
			// If there is a bundle url at all, construct an OCI resolver to fetch the task.
			kc, err := k8schain.New(ctx, k8s, k8schain.Options{
				Namespace:          namespace,
				ServiceAccountName: saName,
			})
			if err != nil {
				return nil, nil, fmt.Errorf("failed to get keychain: %w", err)
			}
			resolver := oci.NewResolver(tr.Bundle, kc)

			return resolveTask(ctx, resolver, name, kind, k8s)
		}
	case tr != nil && tr.Resolver != "" && requester != nil:
		// Return an inline function that implements GetTask by calling Resolver.Get with the specified task type and
		// casting it to a TaskObject.
		return func(ctx context.Context, name string) (v1beta1.TaskObject, *v1beta1.ConfigSource, error) {
			var replacedParams []v1beta1.Param
			if ownerAsTR, ok := owner.(*v1beta1.TaskRun); ok {
				stringReplacements, arrayReplacements := paramsFromTaskRun(ctx, ownerAsTR)
				for k, v := range getContextReplacements("", ownerAsTR) {
					stringReplacements[k] = v
				}
				for _, p := range tr.Params {
					p.Value.ApplyReplacements(stringReplacements, arrayReplacements, nil)
					replacedParams = append(replacedParams, p)
				}
			} else {
				replacedParams = append(replacedParams, tr.Params...)
			}
			resolver := resolution.NewResolver(requester, owner, string(tr.Resolver), trName, namespace, replacedParams)
			return resolveTask(ctx, resolver, name, kind, k8s)
		}

	default:
		// Even if there is no task ref, we should try to return a local resolver.
		local := &LocalTaskRefResolver{
			Namespace:    namespace,
			Kind:         kind,
			Tektonclient: tekton,
		}
		return local.GetTask
	}
}

// resolveTask accepts an impl of remote.Resolver and attempts to
// fetch a task with given name. An error is returned if the
// remoteresource doesn't work or the returned data isn't a valid
// v1beta1.TaskObject.
func resolveTask(ctx context.Context, resolver remote.Resolver, name string, kind v1beta1.TaskKind, k8s kubernetes.Interface) (v1beta1.TaskObject, *v1beta1.ConfigSource, error) {
	// Because the resolver will only return references with the same kind (eg ClusterTask), this will ensure we
	// don't accidentally return a Task with the same name but different kind.
	obj, configSource, err := resolver.Get(ctx, strings.TrimSuffix(strings.ToLower(string(kind)), "s"), name)
	if err != nil {
		return nil, nil, err
	}
	taskObj, err := readRuntimeObjectAsTask(ctx, obj)
	if err != nil {
		return nil, nil, fmt.Errorf("failed to convert obj %s into Task", obj.GetObjectKind().GroupVersionKind().String())
	}
	return taskObj, configSource, nil
}

// readRuntimeObjectAsTask tries to convert a generic runtime.Object
// into a v1beta1.TaskObject type so that its meta and spec fields
// can be read. An error is returned if the given object is not a
// TaskObject or if there is an error validating or upgrading an
// older TaskObject into its v1beta1 equivalent.
func readRuntimeObjectAsTask(ctx context.Context, obj runtime.Object) (v1beta1.TaskObject, error) {
	if task, ok := obj.(v1beta1.TaskObject); ok {
		return task, nil
	}
	return nil, errors.New("resource is not a task")
}

// LocalTaskRefResolver uses the current cluster to resolve a task reference.
type LocalTaskRefResolver struct {
	Namespace    string
	Kind         v1beta1.TaskKind
	Tektonclient clientset.Interface
}

// GetTask will resolve either a Task or ClusterTask from the local cluster using a versioned Tekton client. It will
// return an error if it can't find an appropriate Task for any reason.
// TODO: if we want to set source for in-cluster task, set it here.
// https://github.com/tektoncd/pipeline/issues/5522
func (l *LocalTaskRefResolver) GetTask(ctx context.Context, name string) (v1beta1.TaskObject, *v1beta1.ConfigSource, error) {
	if l.Kind == v1beta1.ClusterTaskKind {
		task, err := l.Tektonclient.TektonV1beta1().ClusterTasks().Get(ctx, name, metav1.GetOptions{})
		if err != nil {
			return nil, nil, err
		}
		return task, nil, nil
	}

	// If we are going to resolve this reference locally, we need a namespace scope.
	if l.Namespace == "" {
		return nil, nil, fmt.Errorf("must specify namespace to resolve reference to task %s", name)
	}
	task, err := l.Tektonclient.TektonV1beta1().Tasks(l.Namespace).Get(ctx, name, metav1.GetOptions{})
	if err != nil {
		return nil, nil, err
	}
	return task, nil, nil
}

// IsGetTaskErrTransient returns true if an error returned by GetTask is retryable.
func IsGetTaskErrTransient(err error) bool {
	return strings.Contains(err.Error(), errEtcdLeaderChange)
}