timedatectl list-timezones | grep Kiev
Europe/Kiev

sudo timedatectl set-timezone Europe/Kiev

timedatectl status

Local time: Wed 2017-11-29 13:41:12 EET
Universal time: Wed 2017-11-29 11:41:12 UTC
RTC time: Wed 2017-11-29 11:41:12
Time zone: Europe/Kiev (EET, +0200)
Network time on: no
NTP synchronized: yes
RTC in local TZ: no

just put in /etc/coreos/update.conf
line

REBOOT_STRATEGY=off

For coreos that's enough to use something like this

docker run -d \
  -v /home/core/certificates:/etc/nginx/certs:rw \
  --volumes-from nginx-proxy \
  -v /var/run/docker.sock:/var/run/docker.sock:ro \
  jrcs/letsencrypt-nginx-proxy-companion

docker run -d -p 80:80 -p 443:443 \
  --name nginx-proxy \
  -v /home/core/certificates:/etc/nginx/certs:ro \
  -v /etc/nginx/vhost.d \
  -v /usr/share/nginx/html \
  -v /var/run/docker.sock:/tmp/docker.sock:ro \
  -v /home/core/conf.d/external.conf:/etc/nginx/conf.d/external.conf  \
  --restart always \
  jwilder/nginx-proxy

and then not to forget to specify

LETSENCRYPT_HOST=mydomain.com
LETSENCRYPT_EMAIL=my@email.com

in your docker-compose section.

More is here https://hub.docker.com/r/mickaelperrin/docker-letsencrypt-nginx-proxy-companion/

Shut down and reboot the system:

$ systemctl reboot

Shut down and power-off the system:

$ systemctl poweroff

Easy peasy:
edit /etc/coreos/update.conf file and change from GROUP=stable to GROUP=beta

after that do

sudo systemctl restart update-engine

and watch logs

journalctl -f -u update-engine

In order to make backup more secure I dont want to share my private key, instead I'll create separate key for backup and supply to coreos and backup scripts.

Supplying to CoreOS is something different then other OSes.

echo 'ssh-rsa AAAAB3 ....' | update-ssh-keys -a core

does it's job and key should survive after reboots.

Find your timezone via this shell command

timedatectl list-timezones

And then set it up like this

sudo timedatectl set-timezone Europe/Kiev

Here is simple systemd unit for coreos docker monitoring in zabbix.

Put this in /etc/systemd/system/zabbix-agent.service

[Unit]
Description=Zabbix agent
After=docker.service
Requires=docker.service

[Service]
ExecStartPre=-/usr/bin/docker kill zabbix-agent-xxl
ExecStartPre=-/usr/bin/docker rm zabbix-agent-xxl
ExecStart=/usr/bin/docker run  --name=zabbix-agent-xxl -p 10050:10050  -v /:/rootfs  -v /var/run:/var/run -e "ZA_Server=yourzabbix.server.com"  monitoringartist/zabbix-agent-xxl-limited:latest
ExecStop=/usr/bin/docker stop zabbix-agent-xxl

And launch with

systemctl enable zabbix-agent

systemctl start zabbix-agent

Inspect running container with

docker ps

, it should be running.

Please note, that every time zabbix container could not be started, it should be recreated.

CoreOS does not have crontab and should not. It uses new concept of Timers for Services.

For instance I have to reindex Sphinx database in container every 15 minutes, how should I do this?

Proper way is to do like this:

1. create service reindex.service
   sudo vim /etc/systemd/system/reindex.service

[Unit]
Description=Reindexes sphinx container

[Service]
Type=oneshot
ExecStart=/usr/bin/docker exec itservice_search_1 /index.sh

1. create timer for reindex service:
   sudo vim /etc/systemd/system/reindex.timer

cat		Output the contents of a submitted unit
[Unit]
Description=Run reindex.service every 10 minutes

[Timer]
OnCalendar=*:0/15

Next, we should enable this service and timer like this:

sudo systemctl enable reindex.service
sudo systemctl enable reindex.timer
sudo systemctl start reindex.timer

You can control your timers like:

systemctl list-timers

and watch service logs

journalctl -f -u reindex.service

При помощи этого контейнера:

https://github.com/bhuisgen/docker-zabbix-coreos

Код для запуска контейнера

docker run -d -p 10050:10050 -u 0 -c 1024 -m 64M --memory-swap=-1 \
    -v /proc:/coreos/proc:ro -v /sys:/coreos/sys:ro -v /dev:/coreos/dev:ro \
    -v /var/run/docker.sock:/coreos/var/run/docker.sock \
    --name zabbix-coreos bhuisgen/docker-zabbix-coreos my-zabbix-server.com my-cluster-code

Где my-zabbix-server.com это ваш zabbix-server

а my-cluster-code ваш код meta для автообнаружения.

После настройки автообнаружения у вас появится хост в нужном месте.