Public bug reported:
We have a 16.04 Ubuntu lx-brand container image available in our public
cloud and recently discovered a systemd bug that's related to running in
a container environment.
I'm forwarded below what one of our engineers discovered:
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After installing postgres (apt-get install -y -q postgresql), systemd
does not actually start any of the postgres services. We tracked this
down to a failure from sed from within the /lib/systemd/system-
generators/postgresql-generator script. The sed command tries to close
stderr (fd 2) which fails, so sed returns an error code, which causes
the entire postgres generator to fail.
The root cause of the problem lies in the systemd code. Because we are
running inside of a container (see detect_container) we don't execute
the following block of code in the systemd main().
if (getpid() == 1 && detect_container() <= 0) {
/* Running outside of a container as PID 1 */
arg_running_as = MANAGER_SYSTEM;
make_null_stdio();
The make_null_stdio function is what sets up fd 0-2 as /dev/null in
systemd on bare metal. Having those fd's setup is what allows the
postgres system-generator to work properly since sed expects to be able
to close stderr.
Because we never call make_null_stdio when inside any container, the low
fd's wind up getting setup later using /dev/console with O_CLOEXEC, so
when we actually run the system generator script, we don't have the low
fd's setup at all like sed expects.
Interestingly, looking at the master branch of systemd, at
src/core/main.c this bug appears to no longer exist. The relevant code
block has been moved so it is no longer conditional on being in a
container, but the commit was not intended to fix this problem. It was
apparently due to color handling on the console/
commit 3a18b60489504056f9b0b1a139439cbfa60a87e1
It would be great if this fix could be pulled in to an update for Ubuntu
16.04.
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** Affects: systemd (Ubuntu)
Importance: Undecided
Status: New
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https://bugs.launchpad.net/bugs/1608953
Title:
Issue with systemd issue when run inside a container
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