我可以在Linux服务器上安装两个Chef客户端，以便两个客户端都可以管理Linux服务器吗？

Question

I want to install one chef client on a linux server to manage the server by executing shell command. While there is a reboot command in one of the recipes in the run list, and the rest recipes don't continue to execute after the server reboot. As I haven't found a way to solve it, I wonder if I can install two chef clients on a Linux server and execute different recipes so that the rest recipes can continue to execute after the server reboot. Anyone can help? Thanks.

Answer 1

Putting two clients on a single device, or two Configuration Management tools on the same box in general, is a Bad Idea. Even if you could do it the cognitive load increase from determining when to update what where going forward is going to open you up to mistakes.

The proper approach is to put restart flags in your recipes; before you call the restart resource you set a flag (which can be a files contents or even existence, an environment variable, or any number of other persistent data objects) to indicate that a restart was performed. If its to be periodic you can instead look at something like the last time a file was accessed with its atime property. Then you do logic around your steps that require a reboot, guarding against a reboot if the flag no-restart flag is set or triggering it if you have a restart flag set, your choice. That way you'll have a chef converge with a restart that skips part of your runlist, then later another run that skips the unnecessary restart process.

Another good option is to just pay more attention to how you have your resources ordered. If the restart is in your last runlist item and is notified with the :delayed timing then it will be the last run resource, meaning the rest of your recipes would have already converged. If you need a complete converge every time then that is the option you should embrace.

Option 1 is a Ruby-centric solution and will require you to embrace dev work. Option 2 is more pure Chef with some Ruby sprinkled in and you can read up on notifying resources in the docs here: https://docs.chef.io/resource_common.html#notifications

There is an option 3 where you change the runlist during the chef run, which you could use to remove the recipes that require the reboot, but I think you'd benefit more from option 1 or 2.