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Fork syslog-ng into a new process group via bash monitor mode #453

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Merged
Theaxiom merged 2 commits into from
Nov 23, 2017
Merged

Fork syslog-ng into a new process group via bash monitor mode #453

Theaxiom merged 2 commits into from
Nov 23, 2017

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@sundbry
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@sundbry sundbry commented Nov 23, 2017

This prevents SIGINT from a user interrupt from prematurely quitting syslog-ng.
Re: Issue #450 and PR #447

From the bash manual:

-m      Monitor mode.  Job control is enabled.  This option is on by default for interactive shells on systems that support it (see JOB CONTROL above).  Back-
                      ground processes run in a separate process group and a line containing their exit status is printed upon their completion.

When an interactive docker tty receives SIGINT, it forwards the signal to all processes in the tty's process group (https://www.cs.ucsb.edu/~almeroth/classes/W99.276/assignment1/signals.html). By forking syslog-ng into it's own process group with bash monitor mode, this prevents the SIGINT sent to the tty from being sent to syslog-ng, and the normal shutdown procedure is then able to shutdown syslog-ng at the appropriate point in the sequence.

@sundbry
Fork syslog-ng into a new process group via bash monitor mode
b776334 
This prevents SIGINT from a user interrupt from prematurely quitting syslog-ng.
See phusion#450
@sundbry sundbry mentioned this pull request Nov 23, 2017
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@Theaxiom Theaxiom added this to the 0.10.0 milestone Nov 23, 2017
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Theaxiom commented Nov 23, 2017

@sundbry have you tested this?

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sundbry commented Nov 23, 2017

@Theaxiom Yes, tried it with ctrl c, and a normal kill with docker stop

Using the same logger.py from #447

Kill with ctrl-c

docker run -ti --rm --name test -v $(pwd)/test/logger.py:/etc/my_init.d/logger.py phusion/baseimage:0.9.22
*** Running /etc/my_init.d/00_regen_ssh_host_keys.sh...
*** Running /etc/my_init.d/10_syslog-ng.init...
Nov 23 18:06:17 03e724a5c2f1 syslog-ng[11]: syslog-ng starting up; version='3.5.6'
Nov 23 18:06:17 03e724a5c2f1 syslog-ng[11]: WARNING: you are using the pipe driver, underlying file is not a FIFO, it should be used by file(); filename='/dev/stdout'
Nov 23 18:06:18 03e724a5c2f1 syslog-ng[11]: EOF on control channel, closing connection;
*** Running /etc/my_init.d/logger.py...
[18:06:18.700637] Starting
[18:06:18.701101] Ping
Nov 23 18:06:18 03e724a5c2f1 /logger.py[16]: [18:06:18.700637] Starting
Nov 23 18:06:18 03e724a5c2f1 /logger.py[16]: [18:06:18.701101] Ping
[18:06:18.954699] Ping
Nov 23 18:06:18 03e724a5c2f1 /logger.py[16]: [18:06:18.954699] Ping
[18:06:19.206189] Ping
Nov 23 18:06:19 03e724a5c2f1 /logger.py[16]: [18:06:19.206189] Ping
[18:06:19.458966] Ping
Nov 23 18:06:19 03e724a5c2f1 /logger.py[16]: [18:06:19.458966] Ping
[18:06:19.709795] Ping
Nov 23 18:06:19 03e724a5c2f1 /logger.py[16]: [18:06:19.709795] Ping
[18:06:19.960832] Ping
Nov 23 18:06:19 03e724a5c2f1 /logger.py[16]: [18:06:19.960832] Ping
^C[18:06:20.056618] Caught signal SIGINT, ignoring.
*** An error occurred. Aborting.
*** Shutting down /etc/my_init.d/logger.py (PID 16)...
[18:06:20.057728] Caught signal SIGTERM, ignoring.
[18:06:20.211411] Ping
Nov 23 18:06:20 03e724a5c2f1 /logger.py[16]: [18:06:20.211411] Ping
[18:06:20.467293] Ping
Nov 23 18:06:20 03e724a5c2f1 /logger.py[16]: [18:06:20.467293] Ping
[18:06:20.719701] Ping
Nov 23 18:06:20 03e724a5c2f1 /logger.py[16]: [18:06:20.719701] Ping
Nov 23 18:06:20 03e724a5c2f1 /logger.py[16]: [18:06:20.975677] Ping
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Nov 23 18:06:21 03e724a5c2f1 /logger.py[16]: [18:06:21.228114] Ping
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Nov 23 18:06:21 03e724a5c2f1 /logger.py[16]: [18:06:21.484098] Ping
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Nov 23 18:06:21 03e724a5c2f1 /logger.py[16]: [18:06:21.736382] Ping
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Nov 23 18:06:21 03e724a5c2f1 /logger.py[16]: [18:06:21.988131] Ping
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Nov 23 18:06:22 03e724a5c2f1 /logger.py[16]: [18:06:22.241186] Ping
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Nov 23 18:06:22 03e724a5c2f1 /logger.py[16]: [18:06:22.497227] Ping
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Nov 23 18:06:22 03e724a5c2f1 /logger.py[16]: [18:06:22.999930] Ping
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Nov 23 18:06:23 03e724a5c2f1 /logger.py[16]: [18:06:23.250688] Ping
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Nov 23 18:06:23 03e724a5c2f1 /logger.py[16]: [18:06:23.501774] Ping
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Nov 23 18:06:23 03e724a5c2f1 /logger.py[16]: [18:06:23.753184] Ping
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Nov 23 18:06:23 03e724a5c2f1 /logger.py[16]: [18:06:24.003949] Ping
[18:06:24.255745] Ping
Nov 23 18:06:24 03e724a5c2f1 /logger.py[16]: [18:06:24.255745] Ping
[18:06:24.511514] Ping
Nov 23 18:06:24 03e724a5c2f1 /logger.py[16]: [18:06:24.511514] Ping
[18:06:24.766227] Ping
Nov 23 18:06:24 03e724a5c2f1 /logger.py[16]: [18:06:24.766227] Ping
[18:06:25.018023] Ping
Nov 23 18:06:25 03e724a5c2f1 /logger.py[16]: [18:06:25.018023] Ping
*** /etc/my_init.d/logger.py (PID 16) did not shut down in time. Forcing it to exit.
*** Init system aborted.
*** Killing all processes...
Nov 23 18:06:25 03e724a5c2f1 syslog-ng[11]: syslog-ng shutting down; version='3.5.6'

Kill with docker stop

docker run -ti --rm --name test -v $(pwd)/test/logger.py:/etc/my_init.d/logger.py phusion/baseimage:0.9.22
*** Running /etc/my_init.d/00_regen_ssh_host_keys.sh...
*** Running /etc/my_init.d/10_syslog-ng.init...
Nov 23 18:08:10 a22ed876faec syslog-ng[11]: syslog-ng starting up; version='3.5.6'
Nov 23 18:08:10 a22ed876faec syslog-ng[11]: WARNING: you are using the pipe driver, underlying file is not a FIFO, it should be used by file(); filename='/dev/stdout'
Nov 23 18:08:11 a22ed876faec syslog-ng[11]: EOF on control channel, closing connection;
*** Running /etc/my_init.d/logger.py...
[18:08:11.941126] Starting
Nov 23 18:08:11 a22ed876faec /logger.py[16]: [18:08:11.941126] Starting
[18:08:11.941924] Ping
Nov 23 18:08:11 a22ed876faec /logger.py[16]: [18:08:11.941924] Ping
[18:08:12.195546] Ping
Nov 23 18:08:12 a22ed876faec /logger.py[16]: [18:08:12.195546] Ping
[18:08:12.448298] Ping
Nov 23 18:08:12 a22ed876faec /logger.py[16]: [18:08:12.448298] Ping
[18:08:12.702494] Ping
Nov 23 18:08:12 a22ed876faec /logger.py[16]: [18:08:12.702494] Ping
[18:08:12.953930] Ping
Nov 23 18:08:12 a22ed876faec /logger.py[16]: [18:08:12.953930] Ping
[18:08:13.204705] Ping
Nov 23 18:08:13 a22ed876faec /logger.py[16]: [18:08:13.204705] Ping
[18:08:13.455713] Ping
Nov 23 18:08:13 a22ed876faec /logger.py[16]: [18:08:13.455713] Ping
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Nov 23 18:08:13 a22ed876faec /logger.py[16]: [18:08:13.709442] Ping
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Nov 23 18:08:13 a22ed876faec /logger.py[16]: [18:08:13.965485] Ping
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Nov 23 18:08:14 a22ed876faec /logger.py[16]: [18:08:14.217358] Ping
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Nov 23 18:08:14 a22ed876faec /logger.py[16]: [18:08:14.473215] Ping
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Nov 23 18:08:14 a22ed876faec /logger.py[16]: [18:08:14.724741] Ping
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Nov 23 18:08:14 a22ed876faec /logger.py[16]: [18:08:14.976330] Ping
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Nov 23 18:08:15 a22ed876faec /logger.py[16]: [18:08:15.227224] Ping
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Nov 23 18:08:15 a22ed876faec /logger.py[16]: [18:08:15.478073] Ping
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Nov 23 18:08:15 a22ed876faec /logger.py[16]: [18:08:15.729183] Ping
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Nov 23 18:08:15 a22ed876faec /logger.py[16]: [18:08:15.979973] Ping
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Nov 23 18:08:16 a22ed876faec /logger.py[16]: [18:08:16.231814] Ping
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Nov 23 18:08:16 a22ed876faec /logger.py[16]: [18:08:16.486040] Ping
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Nov 23 18:08:16 a22ed876faec /logger.py[16]: [18:08:16.738648] Ping
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Nov 23 18:08:17 a22ed876faec /logger.py[16]: [18:08:17.243947] Ping
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Nov 23 18:08:17 a22ed876faec /logger.py[16]: [18:08:17.495166] Ping
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Nov 23 18:08:17 a22ed876faec /logger.py[16]: [18:08:17.747728] Ping
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Nov 23 18:08:18 a22ed876faec /logger.py[16]: [18:08:18.002310] Ping
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Nov 23 18:08:18 a22ed876faec /logger.py[16]: [18:08:18.253047] Ping
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Nov 23 18:08:18 a22ed876faec /logger.py[16]: [18:08:18.504103] Ping
[18:08:18.758437] Ping
Nov 23 18:08:18 a22ed876faec /logger.py[16]: [18:08:18.758437] Ping
[18:08:19.009905] Ping
Nov 23 18:08:19 a22ed876faec /logger.py[16]: [18:08:19.009905] Ping
[18:08:19.261080] Ping
Nov 23 18:08:19 a22ed876faec /logger.py[16]: [18:08:19.261080] Ping
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Nov 23 18:08:19 a22ed876faec /logger.py[16]: [18:08:19.516725] Ping
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Nov 23 18:08:19 a22ed876faec /logger.py[16]: [18:08:19.772660] Ping
*** An error occurred. Aborting.
*** Shutting down /etc/my_init.d/logger.py (PID 16)...
[18:08:19.890574] Caught signal SIGTERM, ignoring.
[18:08:20.026056] Ping
Nov 23 18:08:20 a22ed876faec /logger.py[16]: [18:08:20.026056] Ping
[18:08:20.277252] Ping
Nov 23 18:08:20 a22ed876faec /logger.py[16]: [18:08:20.277252] Ping
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Nov 23 18:08:20 a22ed876faec /logger.py[16]: [18:08:20.530442] Ping
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Nov 23 18:08:20 a22ed876faec /logger.py[16]: [18:08:20.782034] Ping
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Nov 23 18:08:21 a22ed876faec /logger.py[16]: [18:08:21.033871] Ping
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Nov 23 18:08:21 a22ed876faec /logger.py[16]: [18:08:21.284677] Ping
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Nov 23 18:08:23 a22ed876faec /logger.py[16]: [18:08:23.064992] Ping
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Nov 23 18:08:23 a22ed876faec /logger.py[16]: [18:08:23.319387] Ping
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Nov 23 18:08:23 a22ed876faec /logger.py[16]: [18:08:23.570257] Ping
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Nov 23 18:08:23 a22ed876faec /logger.py[16]: [18:08:23.821054] Ping
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Nov 23 18:08:24 a22ed876faec /logger.py[16]: [18:08:24.071773] Ping
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Nov 23 18:08:24 a22ed876faec /logger.py[16]: [18:08:24.322619] Ping
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Nov 23 18:08:24 a22ed876faec /logger.py[16]: [18:08:24.573583] Ping
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Nov 23 18:08:24 a22ed876faec /logger.py[16]: [18:08:24.824527] Ping
*** /etc/my_init.d/logger.py (PID 16) did not shut down in time. Forcing it to exit.
*** Init system aborted.
*** Killing all processes...
Nov 23 18:08:24 a22ed876faec syslog-ng[11]: syslog-ng shutting down; version='3.5.6'

Theaxiom
Theaxiom approved these changes Nov 23, 2017
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LGTM! 👍

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Theaxiom commented Nov 23, 2017

This can be merged after is passes Travis CI.

@Theaxiom Theaxiom merged commit 06e2983 into phusion:master Nov 23, 2017
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kamermans commented Nov 26, 2017

Nice solution! I had not heard of monitor mode in bash before, but it makes total sense.

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@Theaxiom Theaxiom Theaxiom approved these changes

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