title: Can I have an Azure DevOps Pipeline set a variable based on a group of available options?
body: <p>Essentially, I have, say, 10 Pipelines that all run at the same time on 3 available Agents. So only 3 run at a time, and the rest are queued. I need each pipeline to have a variable that I can use for the entire pipeline, but I need that variable to be chosen from a specific list. Furthermore, I would like the variable that is chosen, to not be able to be chosen by another pipeline while it is being used by one. Once that Pipeline is finished, that variable can then be used again by a different Pipeline. So I would like each Pipeline to choose from a list of available options and set one of those options as a Pipeline variable, then free up that option for a later running Pipeline to be able to choose it again. Is this possible?</p>