prototype fix for auto api relative paths

pkg/engine/project.go

@@ -18,7 +18,6 @@ import (
 	"os"
 	"path"
 	"path/filepath"
-	"strings"
 
 	"github.com/pkg/errors"
 
@@ -50,16 +49,20 @@ func getPwdMain(root, main string) (string, string, error) {
 	if main == "" {
 		main = "."
 	} else {
-		// The path must be relative from the package root.
-		if path.IsAbs(main) {
-			return "", "", errors.New("project 'main' must be a relative path")
-		}
+		// Note: I had to relax constraints on main being a subfolder of root. I tried computing a relative
+		// path from the auto api tmp directory. But the tmp directory on osx is `/private/var/tmp` and
+		// computing a relative path doesn't work as `/private/User/...` (where the program would be) isn't
+		// a valid file path.
+		//
+		// The reason we had this check in the first place is due to PPC constraints for hosted execution. Look through the original PR
+		// https://github.com/pulumi/pulumi/pull/615 https://github.com/pulumi/pulumi-ppc/pull/102
+		// It would appear that it is now safe to allow root and main to be in disjoint file trees.
+		// Empyrically from my testing it seems to work, but would be worth checking with @chrsmith
 
-		// Check that main is a subdirectory.
-		cleanPwd := filepath.Clean(pwd)
-		main = filepath.Clean(filepath.Join(cleanPwd, main))
-		if !strings.HasPrefix(main, cleanPwd) {
-			return "", "", errors.New("project 'main' must be a subfolder")
+		// The path can be relative from the package root.
+		if !path.IsAbs(main) {
+			cleanPwd := filepath.Clean(pwd)
+			main = filepath.Clean(filepath.Join(cleanPwd, main))
 		}
 
 		// So that any relative paths inside of the program are correct, we still need to pass the pwd

sdk/nodejs/x/automation/localWorkspace.ts

@@ -176,8 +176,12 @@ export class LocalWorkspace implements Workspace {
             wsOpts = { ...opts, program: args.program };
         }
 
+        if(!wsOpts.workDir) {
+            wsOpts.workDir = fs.mkdtempSync(upath.joinSafe(os.tmpdir(), "automation-"));
+        }
+
         if (!wsOpts.projectSettings) {
-            wsOpts.projectSettings = defaultProject(args.projectName);
+            wsOpts.projectSettings = defaultProject(args.projectName, wsOpts.workDir);
         }
 
         const ws = new LocalWorkspace(wsOpts);
@@ -643,7 +647,8 @@ function getStackSettingsName(name: string): string {
 
 type StackInitializer = (name: string, workspace: Workspace) => Promise<Stack>;
 
-function defaultProject(projectName: string) {
-    const settings: ProjectSettings = { name: projectName, runtime: "nodejs" };
+function defaultProject(projectName: string, workDir: string) {
+
+    const settings: ProjectSettings = { name: projectName, runtime: "nodejs", main: process.cwd() };
     return settings;
 }