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pythonsubprocessrunc

Python subprocess.communicate fails to capture output from runc container if not run from interactive terminal

I have a script which runs a subprocess and captures the output, but it only works if I run it in an interactive shell, but not if run from Jenkins.

tst_subscriber = ["timeout", "-s", "KILL", str(timeout),"bash","-c", subsciber_executable]
tst_publisher = ["timeout","-s", "KILL", str(timeout),"bash","-c", publisher_executable]
kill_publisher = lambda process: subprocess.call(['docker-runc', 'delete', pub_name, "-f"])
kill_subscriber = lambda process: subprocess.call(['docker-runc', 'delete', sub_name, "-f"])

test_env = os.environ.copy()
# workaround for buffering problem which causes no captured output for python subprocesses
test_env["PYTHONUNBUFFERED"] = "1"

sub_pro = Popen(tst_subscriber, stdout=subprocess.PIPE, env=test_env)
pub_pro = Popen(tst_publisher, stdout=subprocess.PIPE, env=test_env)

timeout_sub = Timer(timeout, kill_subscriber, [sub_pro])
timeout_pub = Timer(timeout, kill_publisher, [pub_pro])

timeout_sub.start()
timeout_pub.start()
(output, err) = sub_pro.communicate()

print "Subscriber stdout:"
print output
print "Subscriber stderr:"
print err
Solution

  • Due to several open runc issues #1965 #1721, setting terminal: true in the config.json leads to difficulties with piping. Seeting terminal: false solved the issue.