Add support for importing models stored in the Modelcar (OCI) format

This allows dsl.import to leverage Modelcar container images in an OCI
repository. This works by having an init container prepull the image and
then adding a sidecar container when the launcher container is running.
The Modelcar container adds a symlink to its /models directory in an
emptyDir volume that is accessible by the launcher container. Once the
launcher is done running the user code, it stops the Modelcar
containers.

This approach has the benefit of leveraging image pull secrets
configured on the Kubernetes cluster rather than require separate
credentials for importing the artifact. Additionally, no data is copied
to the emptyDir volume, so the storage cost is just pulling the Modelcar
container image on the Kubernetes worker node.

Note that once Kubernetes supports OCI images as volume mounts for
several releases, consider replacing the init container with that
approach.

This also adds a new environment variable of PIPELINE_RUN_AS_USER to
set the runAsUser on all pods created by Argo Workflows.

Resolves:
#11584

Signed-off-by: mprahl <mprahl@users.noreply.github.com>

.github/workflows/kfp-samples.yml

@@ -36,9 +36,16 @@ jobs:
       with:
         k8s_version: ${{ matrix.k8s_version }}
 
+    - name: Build and upload the sample Modelcar image to Kind
+      run: |
+        docker build -f samples/v2/modelcar_import/Dockerfile -t registry.domain.local/modelcar:test .
+        kind --name kfp load docker-image registry.domain.local/modelcar:test
+
     - name: Forward API port
       run: ./.github/resources/scripts/forward-port.sh "kubeflow" "ml-pipeline" 8888 8888
 
     - name: Run Samples Tests
+      env:
+        PULL_NUMBER: ${{ github.event.pull_request.number }}
       run: |
         ./backend/src/v2/test/sample-test.sh

backend/src/v2/compiler/argocompiler/argo.go

@@ -120,6 +120,14 @@ func Compile(jobArg *pipelinespec.PipelineJob, kubernetesSpecArg *pipelinespec.S
 			Entrypoint:         tmplEntrypoint,
 		},
 	}
+
+	runAsUser := GetPipelineRunAsUser()
+	if runAsUser != nil {
+		wf.Spec.SecurityContext = &k8score.PodSecurityContext{
+			RunAsUser: GetPipelineRunAsUser(),
+		}
+	}
+
 	c := &workflowCompiler{
 		wf:        wf,
 		templates: make(map[string]*wfapi.Template),

backend/src/v2/compiler/argocompiler/argo_test.go

@@ -36,6 +36,7 @@ func Test_argo_compiler(t *testing.T) {
 		jobPath          string // path of input PipelineJob to compile
 		platformSpecPath string // path of possible input PlatformSpec to compile
 		argoYAMLPath     string // path of expected output argo workflow YAML
+		envVars          map[string]string
 	}{
 		{
 			jobPath:          "../testdata/hello_world.json",
@@ -67,9 +68,33 @@ func Test_argo_compiler(t *testing.T) {
 			platformSpecPath: "",
 			argoYAMLPath:     "testdata/exit_handler.yaml",
 		},
+		{
+			jobPath:          "../testdata/hello_world.json",
+			platformSpecPath: "",
+			argoYAMLPath:     "testdata/hello_world_run_as_user.yaml",
+			envVars:          map[string]string{"PIPELINE_RUN_AS_USER": "1001"},
+		},
 	}
 	for _, tt := range tests {
 		t.Run(fmt.Sprintf("%+v", tt), func(t *testing.T) {
+			prevEnvVars := map[string]string{}
+
+			for envVarName, envVarValue := range tt.envVars {
+				prevEnvVars[envVarName] = os.Getenv(envVarName)
+
+				os.Setenv(envVarName, envVarValue)
+			}
+
+			defer func() {
+				for envVarName, envVarValue := range prevEnvVars {
+					if envVarValue == "" {
+						os.Unsetenv(envVarName)
+					} else {
+						os.Setenv(envVarName, envVarValue)
+					}
+				}
+			}()
+
 			job, platformSpec := load(t, tt.jobPath, tt.platformSpecPath)
 			if *update {
 				wf, err := argocompiler.Compile(job, platformSpec, nil)

backend/src/v2/compiler/argocompiler/container.go

@@ -17,9 +17,11 @@ package argocompiler
 import (
 	"fmt"
 	"os"
+	"strconv"
 	"strings"
 
 	wfapi "github.com/argoproj/argo-workflows/v3/pkg/apis/workflow/v1alpha1"
+	"github.com/golang/glog"
 	"github.com/golang/protobuf/jsonpb"
 	"github.com/kubeflow/pipelines/api/v2alpha1/go/pipelinespec"
 	"github.com/kubeflow/pipelines/backend/src/v2/component"
@@ -36,6 +38,7 @@ const (
 	DriverImageEnvVar        = "V2_DRIVER_IMAGE"
 	DefaultDriverCommand     = "driver"
 	DriverCommandEnvVar      = "V2_DRIVER_COMMAND"
+	PipelineRunAsUserEnvVar  = "PIPELINE_RUN_AS_USER"
 	gcsScratchLocation       = "/gcs"
 	gcsScratchName           = "gcs-scratch"
 	s3ScratchLocation        = "/s3"
@@ -101,6 +104,25 @@ func GetDriverCommand() []string {
 	return strings.Split(driverCommand, " ")
 }
 
+func GetPipelineRunAsUser() *int64 {
+	runAsUserStr := os.Getenv(PipelineRunAsUserEnvVar)
+	if runAsUserStr == "" {
+		return nil
+	}
+
+	runAsUser, err := strconv.ParseInt(runAsUserStr, 10, 64)
+	if err != nil {
+		glog.Error(
+			"Failed to parse the %s environment variable with value %s as an int64: %v",
+			PipelineRunAsUserEnvVar, runAsUserStr, err,
+		)
+
+		return nil
+	}
+
+	return &runAsUser
+}
+
 func (c *workflowCompiler) containerDriverTask(name string, inputs containerDriverInputs) (*wfapi.DAGTask, *containerDriverOutputs) {
 	dagTask := &wfapi.DAGTask{
 		Name:     name,