Signal trapping in containers with enabled initsystem

Product support
1

Good day,

I’m having a problem with a fairly simple setup, our containers do not receive any kind of SIGTERM signal in their scripts. I have tried it with the following simple script:

#!/bin/bash
terminate() {
trap - 15
echo “SIGTERM”
}
trap terminate 15
echo “Idling now…”
while :; do sleep 1; done

I’m setting

ENV INITSYSTEM on

in the dockerfile as well as

CMD /sonah/src/test.sh

to start the script.

When hitting stop in the resin dashboard the container does NOT print SIGTERM.

4

Hi, this is a known issue. I will ping our base images maintainer for more information on this.

8

Do you also happen to overwrite the ENTRYPOINT in your Dockerfile?

10

No, we don’t use an ENTRYPOINT.
Currently this is how our own base images look:

FROM resin/raspberrypi3-python:3.6
ENV INITSYSTEM on

####################
###  Initialize  ###
####################
RUN [ "cross-build-start" ]

# Redacted section, but includes ONLY commands like:
# RUN mkdir <directory>
# COPY <pathonlocal> <pathondevice>
# RUN chmod +x <pathondevice>/<filename>.sh && <pathondevice>/<filename>.sh
# RUN rm -rf <pathondevice>

RUN [ "cross-build-end" ]

We then use this base image in our image like so:

FROM <redacted>
ENV INITSYSTEM on

# Redacted section, but includes ONLY commands like:
# RUN mkdir <directory>
# RUN mkdir <directory> <directory2> ...
# COPY <pathonlocal> <pathondevice>
# RUN chmod +x <pathondevice>/<filename>.sh && <pathondevice>/<filename>.sh
# RUN rm <pathondevice>

RUN chmod +x /sonah/src/test.sh
CMD /sonah/src/test.sh

Greetings, Tarek

11

Hi Tarek,

I got an update from our base images maintainer that we are working on releasing a new set of base images, which should be ready in a few days. We will send you an update on this once ready.

Thanks a lot,
Zahari

1 Like
34

Hi. We have an update on the new images. They are currently available at https://store.docker.com/community/images/balenalib/raspberrypi3-debian-python/tags . Please be aware of the following breaking changes:

  • udev defaults to off
  • INITSYSTEM has been completely removed, so applications that rely on systemd should install and set up systemd in their apps
  • removed automatic mounting of devtmpfs
  • dropped support for Debian Wheezy

Given the list of the changes I pointed to above, we strongly recommend testing the app in an isolated lab environemnt before rolling it to production devices.

1 Like