![]() ![]() Takes IANA time zones as well as "local", Setting the time zone within nf is helpful if you want to consistently make containers with the same time zone, alleviating the need to use the flag every time a container is created or run. This ensures that every container created on your system has the specified time zone set unless overridden by the command line. I don't want to specify this flag for every container I run?Īdministrators and users can set a system-wide default time zone for all of their containers using nf. The time zone setting is permanent for the life of the container. This solves the symlink and environment variable problems that users may have previously encountered. If the specified time zone is local (or happens to be a symlink, as some time zone files are simply a symlink to another file), the flag follows the symlink and mounts the pointed-to file. Functionally, the time zone flag mounts a copy of your specified time zone file found in /usr/share/zoneinfo as /etc/localtime, thus setting the time zone in the container. Setting a time zone works the same on rootful and rootless containers. This flag is also available in the podman create command. $ podman run -tz=Asia/Shanghai alpine date See /usr/share/zoneinfo/ for valid time zones.Īnd here are some examples of it in action: $ date This flag takes area-based time zones, GMT, as well as local, which sets the time zone in the container to match the host machine. Taking a look at the podman-run man page, we can see the new -tz option: $ man podman-run The reserved word local sets the time zone to match your host machine's time zone. The -tz flag takes IANA time zones as well as local. Given all that, there was no easy way to change the system to cause ALL containers to use the desired time zone. For example, Fedora images accept the environment variable, while Alpine images ignore it entirely.Īdditionally, some time zones even share the same abbreviation, such as CST standing both for Central Standard time (in the US) and China Standard time. The TZ environment variable is also a problem since not all services pay attention to the variable, causing users to become confused due to different outcomes to the same setting. These attempts have caused problems since the /etc/localtime file is often a symbolic link and may not do what the user expects. Users have attempted to fix this by mounting the time zone file from the host into the container or by adding an environment variable like TZ=jst. This means that your container running in Tokyo could be reporting that it is running in New York City, depending on where the image was built. Once the image is pulled, the container engine just launches the container based on the hardcoded time zone. There is no installation process to modify the time zone. Usually, the time zone is set to the location where the image or base image was built, or to UTC☐0:00. This image is built with a hardcoded link from /etc/localtime to one time zone. When container engines like Podman, Docker, or CRI-O run containers, they pull down the specified OCI image from a container registry. Wed 04:58:59 AM JST Problem: Container images have an embedded time zone If I force a change to this file to point at Japan, the way the date is reported changes: $ ln -fs. ![]() When you ask the system what time it is, the glibc library reads this link to display the time based on the time zone. On my Fedora machine, I see the following link: $ ls -l /etc/localtime Traditionally, Linux computer systems are installed on a physical or virtual machine, and one of the questions asked during the install is: What time zone is the machine is running in? The installer sets up a link between /etc/localtime and a time zone file. A practical introduction to container terminology. ![]()
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