I'm looking for an enhancement to Ansible that I'm conceiving of as "persistent variables." Specifically, when one part of my script does something that registers a variable, I'm typically using that registration to affect whether or not operations are performed afterwards. However, scripts can fail, and then I've lost that prior state that something happened. Running the script again will typically leave the registered variable in a different state, and the operations that triggered off of the registered variable may not be performed, even though they should be.
For a work-around, for example, looking at packages going to be updated on the system. If the pending package updates include, say, an update to the database software, then my script pseudo code looks like this: # check whether the DB software is going to be updated, record to a file # update database # check if file exists indicating DB software update - flag DB updated # if db updated, run DB migration tool # restart database server # remove flag file indicating DB software being upgraded ----------------------- Or a similar case: # check whether apache web server going to be updated, write a file that indicates apache update # update all packages # check whether file exists indicating apache update # if apache updated - optionally rewrite Apache config # if apache updated - restart apache # remove flag file indicating apache update ------------------------ When I initially wrote my scripts, I recorded the state of whether or not the DB software or Apache was being updated in a variable. However, ansible scripts fail. For example, "update all packages" could update Apache, but then fail for any number of reasons. So I want to capture the state of a potential update in a file, so that if Ansible steps fail, the state that the software has been updated has been captured, so that the next time the script runs, it still does the right thing and restarts Apache, for example. I could restart Apache every time, but that is potentially disruptive to clients, so I don't want to do that except if required. All of which leads me to suggest two enhancements: 1) Persisted state variables - as you can see from the scripts above, I have to write a file saving state (only if update is needed), test that file later - saved into a variable, and then delete the file that holds the state. Instead, if I could conditionally "register" a value for a persistent variable, and then upon successful completion of a script, Ansible itself cleans up all the persistent variables, then I don't need to have steps for: writing to a file, checking that file, and removing that file. This will simplify handling of scenarios where state needs to persist between steps in an Ansible script. 2) Assuming I can get persisted state variables, it would also be useful to enhance the package management tools (portage, yum, apt, etc...) to record persistent state about which packages were updated by an update. Only when the script has run successfully to completion does that variable, and all the packages updated, actually get removed. Now I can write scripts that check whether an update has happened in this run of a script, *or any previously unsuccessful run*. Perhaps there's a better way to accomplish some of the above with existing Ansible tasks, but I've not found it. Eric. -- You received this message because you are subscribed to the Google Groups "Ansible Project" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/ansible-project/bd5e22a2-6fb4-4923-ad06-541de3c98a3d%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
