Enable relative TaskRefs within remote Pipelines

pkg/resolve/remote.go

@@ -3,6 +3,8 @@ package resolve
 import (
 	"context"
 	"fmt"
+	"net/url"
+	"strings"
 
 	"github.com/openshift-pipelines/pipelines-as-code/pkg/matcher"
 	tektonv1 "github.com/tektoncd/pipeline/pkg/apis/pipeline/v1"
@@ -19,6 +21,38 @@ func alreadyFetchedResource[T NamedItem](resources map[string]T, resourceName st
 	return false
 }
 
+func createTaskURL(eventPipelines map[string]*tektonv1.Pipeline, pipeline *tektonv1.Pipeline, tasks []string) ([]string, error) {
+	var pURL *url.URL
+	var err error
+	for ep := range eventPipelines {
+		// ensure the URL to be parsed matches the
+		// remote pipeline of the current PipelineRun
+		if eventPipelines[ep] != pipeline {
+			continue
+		}
+		pURL, err = url.Parse(ep)
+		if err != nil {
+			return tasks, err
+		}
+		pPath := strings.SplitAfter(pURL.Path, "/")
+		// pop the pipeline target path from the URL
+		pPath = pPath[:len(pPath)-1]
+		pURL.Path = strings.Join(pPath, "")
+	}
+	taskURLS := make([]string, len(tasks))
+	for i, t := range tasks {
+		tURL, err := url.Parse(t)
+		if err == nil && tURL.Scheme != "" && tURL.Host != "" {
+			taskURLS[i] = t
+			continue // it's already an absolute URL
+		}
+		tURL = pURL
+		tURL = tURL.JoinPath(t)
+		taskURLS[i] = tURL.String()
+	}
+	return taskURLS, nil
+}
+
 // resolveRemoteResources will get remote tasks or Pipelines from annotations.
 //
 // It already has some tasks or pipeline coming from the tekton directory stored in [types]
@@ -98,6 +132,11 @@ func resolveRemoteResources(ctx context.Context, rt *matcher.RemoteTasks, types
 				if err != nil {
 					return []*tektonv1.PipelineRun{}, fmt.Errorf("error getting remote task from pipeline annotations: %w", err)
 				}
+				// check for relative task references and assemble FQDNs
+				pipelineTasks, err = createTaskURL(fetchedResourcesForEvent.Pipelines, fetchedResourcesForPipelineRun.Pipeline, pipelineTasks)
+				if err != nil {
+					return []*tektonv1.PipelineRun{}, err
+				}
 			}
 		}