vpython: use realpath when invoking virtualenv

Use realpath for virtualenv.pyz to mitigate pypa/virtualenv#1949

Change-Id: I4ddfb78bc435f9791ccae5e87cf5c0da404a110a
Reviewed-on: https://chromium-review.googlesource.com/c/infra/luci/luci-go/+/5449147
Reviewed-by: Brian Ryner <bryner@google.com>
Commit-Queue: Chenlin Fan <fancl@chromium.org>
Auto-Submit: Chenlin Fan <fancl@chromium.org>

vpython/application/application.go

@@ -169,7 +169,7 @@ func (a *Application) ParseEnvs(ctx context.Context) (err error) {
 	// Determine our VirtualEnv base directory.
 	if v, ok := e.Lookup(VirtualEnvRootENV); ok {
 		a.VpythonRoot = v
-	} else {
+	} else if a.VpythonRoot == "" {
 		cdir, err := a.userCacheDir()
 		if err != nil {
 			logging.Infof(ctx, "failed to get user cache dir: %s", err)

vpython/application/application_py3_test.go

@@ -19,6 +19,7 @@ import (
 	"os"
 	"os/exec"
 	"path/filepath"
+	"runtime"
 	"strings"
 	"testing"
 
@@ -58,11 +59,9 @@ func getPythonEnvironment(ver string) *python.Environment {
 }
 
 func setupApp(ctx context.Context, app *Application) context.Context {
-	app.Arguments = append([]string{
-		"-vpython-root",
-		testStorageDir,
-	}, app.Arguments...)
-
+	if app.VpythonRoot == "" {
+		app.VpythonRoot = testStorageDir
+	}
 	app.Initialize(ctx)
 
 	So(app.ParseEnvs(ctx), ShouldBeNil)
@@ -166,6 +165,27 @@ func TestPythonBasic(t *testing.T) {
 					So(has, ShouldBeTrue)
 					So(rc, ShouldEqual, 42)
 				})
+
+				if runtime.GOOS != "windows" {
+					// See https://github.com/pypa/virtualenv/issues/1949
+					Convey("Test symlink root", func() {
+						symlinkRoot := filepath.Join(t.TempDir(), "link")
+						err := os.Symlink(testStorageDir, symlinkRoot)
+						So(err, ShouldBeNil)
+
+						c := cmd(t, &Application{
+							Arguments: []string{
+								"-vpython-spec",
+								testData("default.vpython3"),
+								"-c",
+								"print(123)",
+							},
+							VpythonRoot: symlinkRoot,
+						}, env)
+
+						So(output(c), ShouldEqual, "123")
+					})
+				}
 			})
 		}
 	})

vpython/python/bootstrap.py

@@ -16,6 +16,7 @@
 import os
 import subprocess
 import sys
+import tempfile
 
 if sys.version_info[0] > 2:
   ISOLATION_FLAG = '-I'
@@ -27,10 +28,17 @@
 # Create virtual environment in ${out} directory
 virtualenv = glob.glob(
     os.path.join(os.environ['virtualenv'], '*', 'virtualenv.py*'))[0]
-subprocess.check_call([
-    sys.executable, '-B', ISOLATION_FLAG, virtualenv,
-    '--no-download', '--always-copy', os.environ['out']
-])
+
+with tempfile.TemporaryDirectory() as d:
+  args = [
+      sys.executable, '-B', ISOLATION_FLAG,
+      # Use realpath to mitigate https://github.com/pypa/virtualenv/issues/1949
+      os.path.realpath(virtualenv),
+      '--no-download', '--always-copy', os.environ['out'],
+  ]
+  if virtualenv.endswith('.pyz'):
+    args.extend(['--app-data', d])
+  subprocess.check_call(args)
 
 # Install wheels to virtual environment
 if 'wheels' in os.environ: