[feat] Allow passing post-renderer flag in the upgrade subcommand #195
Description
Feature request summary
Expose --post-renderer flag in the upgrade subcommand.
Motivation
I've noticed that in the event of having installed a chart using the post-renderer flag, the diff is not accurate.
This happens because we are comparing a manifest rendered by helm only, but that it didn't go through the post-render process, contrarily to the released manifest.
If we do helm upgrade "mychart" . --post-renderer ./mypostrenderer.sh, the released manifest pipeline is:
helm rendered chart -> post-renderer manipulation -> manifest_1 (deployed)
After upgrading the chart, If we do: helm upgrade "mychart" . --debug --dry-run, the pipeline is:
helm rendered chart -> manifest_2
To avoid this issue, the plugin would need to expose the --post-renderer flag and forward it to helm.