I'm working on a Jenkins deployment using a wrapper for the standard chart (stable/jenkins). The chart includes a value flag to allow you totally replace the configmap with your own as long as you match the format of the original. But I'm running in to a problem because the checksum annotation in the deployment is based on the original configmap, not my replacement. So I have to manually force the deployment pods to re-roll after updating the configmap. I could use a post-upgrade hook in my own chart with a job that does the scale-down-and-back-up dance, but that seems slightly gross.
This is not currently possible with Helm 2, but will be doable in Helm 3 more directly via chart scripts.
My eventual solution was to fork the jenkins
chart and cut it down to only the parts I needed.