This is a very small container (51 Mb) but still have a working init process, crond and syslog. This is the base image for all my other microcontainers
The unix process ID 1 is the process to receive the SIGTERM signal when you execute a
docker stop <container ID>
if the container has the command CMD ["bash"] then bash process will get the SIGTERM signal and terminate.
All other processes running on the system will just stop without the possibility to shutdown correclty
In this container i have a scipt that handles the init process an uses the supervisor system to start the daemons to run and also catch signals (SIGTERM) to shutdown all processes started by supervisord. This is a modified version of an init script made by Phusion. I've modified it to use supervisor in stead of runit. There are also two directories to run scripts before any daemon is started.
All executable in this directory is run at start, after completion the script is removed from the directory
All executable in this directory is run at every start of the container, ie, at docker run and docker start
Each time the container is started the content of the file /tmp/startup.log is displayed so if your startup scripts generate
vital information to be shown please add that information to that file. This information can be retrieved anytime by
executing docker logs <container id>
In many cases there are som need of things happening att given intervalls, default no cron processs is started in standard images. In this image cron is running together with logrotate to stop the logdfiles to be to big on log running containers.
No all services works without a syslog daemon, if you don't have one running those messages is lost in space, all messages sent via the syslog daemon is saved in /var/log/syslog
Also there are fixed (besideds the init process) assosiated with running linux inside a docker container.
To add other processes to run automaticly, add a file ending with .conf in /etc/supervisor.d/ with a layout like this (/etc/supervisor.d/myprogram.conf)
[program:myprogram]
command=/usr/bin/myprogram
myprogram is the name of this process when working with supervisctl.
Output logs std and error is found in /var/log/supervisor/ and the files begins with the <-stdout|-stderr>superervisor*.log
For more settings please consult the manual FOR supervisor
The supervisor process assumes that a command that ends has stopped so if the command detach it will try to restart it. To work around this problem I have written an extra command to be used for these commands. First you have to make a normal start/stop command and place it in the /etc/init.d that starts the program with
/etc/init.d/command start or
service command start
and stops with
/etc/init.d/command stop or
service command stop
Configure the configure-file (/etc/supervisor.d/myprogram.conf)
[program:myprogram]
command=/my_service myprogram
There is an optional parameter, to run a script after a service has start, e.g to run the script /usr/local/bin/postproc.sh av myprogram is started
[program:myprogram]
command=/my_service myprogram /usr/local/bin/postproc.sh
The console output is owned by the my_init process so any output from commands woun't show in the docker log. To send a text from any command, either at startup och during run, append the output to the file /var/log/startup.log, e.g sending specific text to log
echo "Application is finished" >> /var/log/startup.log
or output from script
/usr/local/bin/myscript >> /var/log/startlog.log
> docker run -d --name alpine nimmis/alpine
> docker logs microbase
*** open logfile
*** Run files in /etc/my_runonce/
*** Run files in /etc/my_runalways/
*** Booting supervisor daemon...
*** Supervisor started as PID 6
2015-08-04 11:34:06,763 CRIT Set uid to user 0
*** Started processes via Supervisor......
crond RUNNING pid 9, uptime 0:00:04
rsyslogd RUNNING pid 10, uptime 0:00:04
> docker exec alpine sh -c 'echo "Testmessage to log" >> /var/log/startup.log'
> docker logs alpine
*** open logfile
*** Run files in /etc/my_runonce/
*** Run files in /etc/my_runalways/
*** Booting supervisor daemon...
*** Supervisor started as PID 6
2015-08-04 11:34:06,763 CRIT Set uid to user 0
*** Started processes via Supervisor......
crond RUNNING pid 9, uptime 0:00:04
rsyslogd RUNNING pid 10, uptime 0:00:04
*** Log: Testmessage to log
>
This continer should normaly run as a daemon i.e with the -d flag attached
docker run -d nimmis/alpine
but if you want to check if all services has been started correctly you can start with the following command
docker run -ti nimmis/alpine
the output, if working correctly should be
docker run -ti nimmis/alpine
*** open logfile
*** Run files in /etc/my_runonce/
*** Run files in /etc/my_runalways/
*** Booting supervisor daemon...
*** Supervisor started as PID 7
2015-01-02 10:45:43,750 CRIT Set uid to user 0
crond[10]: crond (busybox 1.24.1) started, log level 8
*** Started processes via Supervisor......
crond RUNNING pid 10, uptime 0:00:04
rsyslogd RUNNING pid 11, uptime 0:00:04
pressing a CTRL-C in that window or running docker stop <container ID> will generate the following output
*** Shutting down supervisor daemon (PID 7)...
*** Killing all processes...
you can the restart that container with
docker start <container ID>
Accessing the container with a shell can be done with
docker exec -ti <container ID> /bin/sh
This image only contains the latest versions of Apline, the versions are nimmis/alpine: where tag is
| Tag | Alpine version | size |
|---|---|---|
| latest | latest/3.14 |  |
| test | latest/edge |  |
| 3.14 | 3.14 |  |
| 3.13 | 3.13 |  |
| 3.12 | 3.12 |  |
| 3.11 | 3.11 |  |
| 3.10 | 3.10 |  |
| 3.9 | 3.9 |  |
| 3.8 | 3.8 |  |
| 3.7 | 3.7 |  |
| 3.6 | 3.6 |  |
| 3.5 | 3.5 |  |
| 3.4 | 3.4 |  |
| 3.3 | 3.3 |  |
| 3.2 | 3.2 |  |
| 3.1 | 3.1 |  |
| edge | edge |  |