Revert "Don't fail if creating venv didn't succeed. Also provide a wa…

…y to disable creating a venv. (#26778)"

This reverts commit 3ec6e58.

sdks/python/container/boot.go

@@ -20,6 +20,7 @@ package main
 import (
 	"context"
 	"encoding/json"
+	"errors"
 	"flag"
 	"fmt"
 	"log"
@@ -156,20 +157,15 @@ func launchSDKProcess() error {
 	signalChannel := make(chan os.Signal, 1)
 	signal.Notify(signalChannel, syscall.SIGHUP, syscall.SIGINT, syscall.SIGTERM)
 
-	// Create a separate virtual environment (with access to globally installed packages), unless disabled by the user.
-	// This improves usability on runners that persist the execution environment for the boot entrypoint between multiple pipeline executions.
-	if os.Getenv("RUN_PYTHON_SDK_IN_DEFAULT_ENVIRONMENT") == "" {
-		venvDir, err := setupVenv(ctx, logger, "/opt/apache/beam-venv", *id)
-		if err != nil {
-			logger.Printf(ctx, "Using default environment, since creating a virtual environment for the SDK harness didn't succeed: %v", err)
-		} else {
-			cleanupFunc := func() {
-				os.RemoveAll(venvDir)
-				logger.Printf(ctx, "Cleaned up temporary venv for worker %v.", *id)
-			}
-			defer cleanupFunc()
-		}
+	venvDir, err := setupVenv(ctx, logger, "/opt/apache/beam-venv", *id)
+	if err != nil {
+		return errors.New("failed to initialize Python venv")
 	}
+	cleanupFunc := func() {
+		os.RemoveAll(venvDir)
+		logger.Printf(ctx, "Cleaned up temporary venv for worker %v.", *id)
+	}
+	defer cleanupFunc()
 
 	dir := filepath.Join(*semiPersistDir, "staged")
 	files, err := artifact.Materialize(ctx, *artifactEndpoint, info.GetDependencies(), info.GetRetrievalToken(), dir)
@@ -312,8 +308,9 @@ func StartCommandEnv(env map[string]string, prog string, args ...string) *exec.C
 
 // setupVenv initializes a local Python venv and sets the corresponding env variables
 func setupVenv(ctx context.Context, logger *tools.Logger, baseDir, workerId string) (string, error) {
+	logger.Printf(ctx, "Initializing temporary Python venv ...")
+
 	dir := filepath.Join(baseDir, "beam-venv-worker-"+workerId)
-	logger.Printf(ctx, "Initializing temporary Python venv in %v", dir)
 	if _, err := os.Stat(dir); !os.IsNotExist(err) {
 		// Probably leftovers from a previous run
 		logger.Printf(ctx, "Cleaning up previous venv ...")