[sonic-buildimage] sync timezone to docker, so the docker has the cor…

[richard28530]

- What I did
sync timezone to docker

- How to verify it
change the switch timezone, reload the config to check the date time is correct

admin@SONiC:$ date
Thu Mar 1 14:39:14 HKT 2018
admin@SONiC:$
admin@SONiC:$
admin@SONiC:$
admin@SONiC:~$ docker exec -it bgp bash
root@SONiC:/# date
Thu Mar 1 14:39:28 HKT 2018
root@SONiC:/#

[lguohan]

do you need to configure as rw? can you mount as ro? since you want the timezone in docker to be in sync with baseimage, then you do not really want to change the timezone in the baseimage, right?

[richard28530]

I tried ro, but dpkg-reconfigure -f noninteractive tzdata need write permission, or it will not update ok. this command will not change the file content.

[lguohan]

how about using -e TZ=timezone approach, seems easier. moby/moby#12084

Just need to change the docker_image_ctl.j2.

[richard28530]

if using -e TZ=timezone approach, we should start new container each every time.
I don't know if we can take this.

[lguohan]

are you saying each every time we change time zone, we need to restart the container?

[richard28530]

'docker start' not support flag -e, so if we we want to do it here, we need delete the docker container first, then start an new container. as we delete the container the modification the history log will be deleted too, so I don't know if this is acceptable.

start() {
docker rm -f swss
echo "Starting new swss container with HWSKU $HWSKU"
docker run -d --net=host --privileged -t -v /etc/network/interfaces:/etc/network/interfaces:ro -v /etc/network/interfaces.d/:/etc/network/interfaces.d/:ro -v /host/machine.conf:/host/machine.conf:ro -v /etc/sonic:/etc/sonic:ro -v /var/log/swss:/var/log/swss:rw  \
    --log-opt max-size=2M --log-opt max-file=5 \
    -v /var/run/redis:/var/run/redis:rw \
    -v /etc/timezone:/etc/timezone:rw \
    -v /usr/share/sonic/device/$PLATFORM:/usr/share/sonic/platform:ro \
    -v /usr/share/sonic/device/$PLATFORM/$HWSKU:/usr/share/sonic/hwsku:ro \
    --tmpfs /tmp \
    --tmpfs /var/tmp \
    --name=swss docker-orchagent-nephos:latest

postStartAction
}

[rodnymolina]

How often would you need to change your switches' timezones? Taking into account that docker containers are by default synchronized with the host, and that you typically set the timezone during switch installation/deployment, i wouldn't expect this to be a common operation. If that's the case, i would rather go with the "docker run -e" option, even though that requires the elimination/creation of the containers. Personally, i prefer that option over the current one of mounting yet-another host-system file as RW.

[lguohan]

the risk of mount /etc/timezone as rw is the the docker application can then modify the file, which can affect the base image and other dockers as well.

I am still not quite clear about the requirement here. is this just one timer change or everytime we change the host timezone we also need to change the timezone within the docker container? @richard28530 , Can you help to clarify the requirement so that we are all on the same page?

[richard28530]

@lguohan the requirement is when I set the timezone on the host, I restart host or restart all the services, after that the logs in the host and the docker container will have the correct timestamp.

this should be repeatable.

When we build the installer image, we have the default timezone UTC, at first startup we create an docker container with UTC.
Then we configure the timezone(HongKong eg.) with Linux command on host, and sync timezone to all docker container.
Operate one or more time should be the same procedure.

use -e flags is ok for me, if you all think is ok too, I will try this way.