Improve error msg on failure to find runtime deps

2 files changed, 39 insertions, 3 deletions

diff --git a/exts/pip.find_deps b/exts/pip.find_deps
index 8c4f432..d788143 100755
--- a/exts/pip.find_deps
+++ b/exts/pip.find_deps
@@ -25,6 +25,7 @@ import os
 import json
 import tempfile
 import logging
+import select
 
 import pkg_resources
 import xmlrpclib
@@ -245,13 +246,45 @@ def find_runtime_deps(source, name, version=None):
 
     # Some temporary file needed for storing the requirements
     tmpfd, tmppath = tempfile.mkstemp()
+    logging.debug('Writing install requirements to: %s', tmppath)
 
     p = subprocess.Popen(['pip', 'install', '.',
                             '--list-dependencies=%s' % tmppath], cwd=source,
-                            stdout=subprocess.PIPE)
+                            stdout=subprocess.PIPE, stderr=subprocess.PIPE,
+                            stdin=subprocess.PIPE)
 
-    if p.wait() != 0:
-        error('pip install --list-dependencies command failed')
+    # We close stdin on parent side to prevent the child from blocking
+    # if it reads on stdin
+    p.stdin.close()
+
+    poll = select.poll()
+
+    logging.debug('p.stdout: %s' % p.stdout)
+    logging.debug('p.stderr: %s' % p.stderr)
+
+    fdmap = {p.stdout.fileno(): p.stdout, p.stderr.fileno(): p.stderr}
+    poll.register(p.stdout)
+    poll.register(p.stderr)
+
+    # Multiplex stdout and stderr
+    # TODO: replace by setting stderr=stdout
+    while fdmap != {}:
+        fds = poll.poll()
+
+        for (fd, _) in fds:
+            line = fdmap[fd].readline()
+            if line == '':
+                poll.unregister(fd)
+                del fdmap[fd]
+            else:
+                logging.debug('%s' % line.rstrip())
+
+    p.wait()    # even with eof on both streams, we still wait
+
+    logging.debug('pip exited with code: %d' % p.returncode)
+
+    if p.returncode != 0:
+        error('failed to get runtime dependencies')
 
     with os.fdopen(tmpfd) as tmpfile:
         ss = resolve_specs(pkg_resources.parse_requirements(tmpfile))
diff --git a/exts/pip.to_lorry b/exts/pip.to_lorry
index be207f7..d537851 100755
--- a/exts/pip.to_lorry
+++ b/exts/pip.to_lorry
@@ -64,6 +64,7 @@ def find_repo_type(url):
         poll.register(p.stderr)
 
         # Multiplex stdout and stderr
+        # TODO: replace this by setting stderr=stdout
         while fdmap != {}:
             fds = poll.poll()
 
@@ -75,6 +76,8 @@ def find_repo_type(url):
                 else:
                     logging.debug('%s' % line)
 
+        p.wait()    # even with eof on both streams, we still wait
+
         shutil.rmtree(tempdir)
 
         if p.returncode == 0: