[modules] Dependent command packages can now be built with ko

[dprotaso]

Thus if you have a (in)direct command package as a dependency
say myhost.com/go/package/cmd/run you can now publish this
with the following ko command

$  ko publish myhost.com/go/package/cmd/run

This follows go's module/vendor semantics. Thus go1.14 by default will use vendored modules. With go1.13 you need the explicit flags to use vendored deps

$  GOFLAGS="-mod=vendor" ko publish myhost.com/go/package/cmd/run

Subsequently in yaml files you can drop the superfluous prefixes

ie. this (in a non-module world)

apiVersion: batch/v1
kind: Job
spec:
  containers:
  - name: vegeta
    image: knative.dev/serving/vendor/github.com/tsenart/vegeta

becomes this in the module world

apiVersion: batch/v1
kind: Job
spec:
  containers:
  - name: vegeta
    image: github.com/tsenart/vegeta

[dprotaso]

cc #152

[imjasonh]

I'm not sure I understand what this is trying to achieve. Is the effect that you can ko build a non-package main package?

[dprotaso]

whoops needs a rebase - one minute

[dprotaso]

Failure in CI is go1.12

pkg/build/gobuild.go:134: Errorf format %w has unknown verb w

1.12 is EOL so I made #156

[mattmoor]

@imjasonh If I'm reading the description correctly, this is the ko publish complement of my change.

[mattmoor]

couldn't we hit N of these? Which one wins?

[dprotaso]

I believe there's only one

[dprotaso]

main != package main but specifically "main module" = root module

[mattmoor]

that's not confusing at all 🙄

[mattmoor]

Ok, so reading through the change, I want to make sure I understand...

With my change, a vendored main module foo will work if it is written as ko://foo, but what you are doing is dumping all of the referenced modules, so that just foo still works.

Since in ko publish qualify local import turns ./vendor/foo into foo with modules, this unblocks letting ko publish ./vendor/foo or ko publish foo from working.

@dprotaso is that right?

[dprotaso]

this unblocks letting ko publish ./vendor/foo or ko publish foo from working.

This unblocks ko publish foo
This does not unblock ko publish ./vendor/foo

[mattmoor]

I wonder, would simply having qualifyLocalImport slap a ko:// on the front of what it produces work?

[dprotaso]

🤷‍♂️

[mattmoor]

This just makes me want to deprecated non-ko:// faster, but it seems like an improvement of the status quo. thanks for chasing this down.