[Proposal] Have kn look up plugins on $PATH by default

[psschwei]

Feature request

The kn client by default will look in $PATH for plugins. This would mirror the performance of kubectl and provide an easier way for users to install plugins using tools like brew.

Use case

This arose out of discussions about the quickstart plugin we're building. The goal of that plugin was to provide a streamlined experience for new users to get up and running on Knative by running something like:

brew install knative/client/kn
brew install knative-sandbox/kn-plugins/quickstart
kn quickstart kind

However, the last command does not work, as kn by default does not look up plugins from $PATH (which is where brew installs them).

See also disucssion in Slack and in the homebrew-kn-plugins repo.

/kind proposal
cc @omerbensaadon @csantanapr

[maximilien]

In principle I am not against this. As discussed in the QuickStart PR I have added the link to show that this is how plugins worked initially for kn.

However, as I recall, there was lots of discussions (which you can revive and re-read, if you want, by searching plugin related issues and PRs) that resulted in where we are. So essentially this rehashes past decisions.

Since I've always been for look up in PATH as default --- simply because I wanted kn to behave like kubectl and I am pretty sure have mentioned this in these issues and PRs, I will recuse myself from this discussion until needed.

Good thing in all of this is that the implementation to make PATH lookup default is a one liner + any test changes :) so hopefully decision is as quick. Cheers 🍻

[duglin]

+1 to this - I never liked that we didn't look in the PATH to being with :-)

[csantanapr]

+1 on looking in PATH like kubectl and oc plugins

[lance]

I like the idea of looking in $PATH for func because func can also be used standalone - i.e. not as a plugin - which is how I usually use it. If it's in my path then func create and kn func create are the same.

[rhuss]

it's in my path then func create and kn func create are the same.

That's not true, it's still need to be called kn-func. So kn-func and kn func would be equivalent.

[rhuss]

I think we can allow a PATH lookup if we still can keep lookup from ~/.config/kn/plugins.

My proposal would be:

• Lookup plugins from both, the path and ~/.config/kn/plugins.
• Same named plugin in ~/.config/kn/plugins take precedence over plugins found on the PATH.

This would also allow for system-wide plugins as installed by brew in /usr/local/bin, but allow individual users to override plugins in their ~/.config/kn/plugins directory.

Also, for people that currently collect their plugins in ~/.config/kn/plugins nothing would change. It's just as if you would add this directory to the front of your $PATH. I would then even remove the config variable lookupConfigInPath as this would be always true then.

Actually, that was also my suggestion anyway when I proposed it at that time as a compromise for a discussion that was more heated then need to be :) --> #269 (comment)

[rhuss]

Decided in the WG Call: Let's go with this approach as this is the kubectl behaviour plus some own extension that could be used (or not) and allows user-specific plugins.

[psschwei]

/assign