2019-01-02 how to change date wi

1. try to see the date within a container first :
   docker exec -it container-id date
   now you see the date result is the same as the OS date

2. if you set OS date by sudo date -s "2019-01-01T01:00:00" && date in a test machine , then run command in #1 again, you will see container gets the new date as OS.

In one word, all containers share the same OS date or say clock.

3. to know the timezone inside a container :
   docker exec -it container-id cat /etc/timezone
   or use echo $TZ if there is such ENV Variable inside the container.
4. to set timezone in a container

docker run -e TZ=America/New_York ubuntu date

5. try to set date inside a container:

docker run -it -P --rm -v $(pwd):/code -e TZ="Asia/Shanghai" -e "NODE_ENV=production" --name taobao-sup-callback-dev node sh -ic ' date -s "2019-01-01T01:00:00" &&  date'

this returns error :
date: cannot set date: Operation not permitted 20190101

6. search online and add --privileged to see if helps:

docker run -it --privileged -P --rm -v $(pwd):/code -e TZ="Asia/Shanghai" -e "NODE_ENV=production" --name taobao-sup-callback-dev node sh -ic ' date -s "2019-01-01T01:00:00" &&  date'

it does helps! but it changed the OS machine time!

so use date -s "2019-01-02T14:52:00" in OS to change back the system time !
This proves that docker use the machine time and if allowed to change the time, it changes system time

another way works the same:
docker run -it --cap-add SYS_TIME --rm --name centos centos /bin/bash

7. so it seems impossible to change container time if you do not want to change machine time ?

I thought so.

But I have to make it work!
So I finally find my solution :
docker run -itd -P --rm -v $(pwd):/code -e TZ="America/Adak" -e "NODE_ENV=production" --name taobao-sup-callback-dev node sh -ic ' cd /code && DEBUG=* /code/node_modules/nodemon/bin/nodemon.js app.js > sup-log.txt'