Helmfile: Proposal: `helmfile list` command

[gorzek]

A useful feature would be a helmfile command that lists out every release a command with the same flags would affect. It would work similarly to helm list (and helm list --short in particular).

For instance, say I have a helmfile.d directory that contains helmfiles for several releases. The names from releases.name would be printed out based on selector rules.

Right now, the output of commands like status and lint is quite verbose and would require a lot of parsing to see what the actual release names are. A simple command that lets one see the actual release names implicated by a particular helmfile.d directory and chosen selectors would be helpful for a lot of automation purposes.

[mumoshu]

@gorzek Thanks for writing this up!

Would you feel ok if I added helmfile list --short that works almost like yours, but adds tiller namespaces to the output?

tiller-system-1/envoy
tiller-system-2/mysql

And helmfile list:

TILLER NAMESPACE    NAME    REVISION    UPDATED                     STATUS      CHART       APP VERSION NAMESPACE
tiller-system-1     envoy   1           Thu May  9 14:46:08 2019    DEPLOYED    envoy-1.5.0 1.9.0       default
tiller-system-2     mysql   1           Thu May  9 14:46:08 2019    FAILED      mysql-x.x.x a.b.c       default

The rationale is that helmfile allows you to use different tiller namespace per release. So printing only release names may end up with many duplicate release names, which is completely valid from the helmfile perspective, but confusing from the user perspective.

WDYT?

[gorzek]

That would be easy enough to parse for my purposes, so that's fine by me.