Forward stderr from failing pex process in exception (#114)

* Forward stderr from failing pex process in exception

This will allow to easily know the reason of pew build error when the user
only gets the python exception without an easy access to error logs (e.g.
in a notebook)

cluster_pack/packaging.py

@@ -34,6 +34,10 @@ class PexTooLargeError(RuntimeError):
     pass
 
 
+class PexCreationError(RuntimeError):
+    pass
+
+
 class PythonEnvDescription(NamedTuple):
     path_to_archive: str
     interpreter_cmd: str
@@ -181,15 +185,15 @@ def pack_in_pex(requirements: List[str],
             call = subprocess.run(cmd, stderr=subprocess.PIPE, stdout=subprocess.PIPE)
             call.check_returncode()
 
-            if not allow_large_pex and os.path.getsize(output + tmp_ext) > 2 * 1024 * 1024 * 1024:
-                raise PexTooLargeError("The generate pex is larger than 2Gb and won't be executable"
-                                       " by python; Please set the 'allow_large_pex' "
-                                       "flag in upload_env")
-
         except CalledProcessError as err:
             _logger.exception('Cannot create pex')
             _logger.exception(err.stderr.decode("ascii"))
-            raise
+            raise PexCreationError(err.stderr.decode("ascii"))
+
+        if not allow_large_pex and os.path.getsize(output + tmp_ext) > 2 * 1024 * 1024 * 1024:
+            raise PexTooLargeError("The generate pex is larger than 2Gb and won't be executable"
+                                   " by python; Please set the 'allow_large_pex' "
+                                   "flag in upload_env")
 
         if allow_large_pex:
             shutil.make_archive(output, 'zip', output + tmp_ext)

tests/test_uploader.py

@@ -356,7 +356,7 @@ def test_format_pex_requirements():
             pex_inherit_path="false")
         pex_info = PexInfo.from_pex(f"{tempdir}/out.pex")
         cleaned_requirements = uploader._format_pex_requirements(pex_info)
-        pip_version = 'pip==21.3.1' if sys.version_info.minor == 6 else 'pip==23.3'
+        pip_version = 'pip==21.3.1' if sys.version_info.minor == 6 else 'pip==23.3.1'
         assert [pip_version, 'pipdeptree==2.0.0', 'six==1.15.0'] == cleaned_requirements