FAQ: document the removal of unnecessary packages, currently via dep prune

[kevinburke]

If I run dep init for this file:

package main

import (
	"crypto/rand"
	"log"

	"golang.org/x/crypto/ed25519"
)

func main() {
	_, _, err := ed25519.GenerateKey(rand.Reader)
	if err != nil {
		log.Fatal(err)
	}
}

The entire golang.org/x/crypto package gets checked into my vendor directory, which is sort of sad because I only need three files (out of 259) in that repo. This means more disk, more bandwidth, longer checkouts, harder to find what you are looking for &c.

It also seems like dep has the ability to determine which packages in a Git repo are actually being used, in the lock file:

[[projects]]
  branch = "master"
  name = "golang.org/x/crypto"
  packages = ["ed25519","ed25519/internal/edwards25519"]
  revision = "358f15eacb587b056fc93273b930314a5cda12fe"

It would be nice if dep only put the packages you needed in vendor or at the very least if there was an FAQ to the effect of "Why is dep checking in the entire Git repo when I only need one package?"

[kevinburke]

(my apologies if this has been previously reported - I scanned the FAQ questions, searched for "vendor git", "vendor git repo" and didn't see anything promising)

[sdboyer]

hi! dep prune will do what you want 😄

at some point - see the bottom of #120 - we intend to pull prune back up into dep ensure. just waitin for someone to find the time to work on it 😇

[sdboyer]

actually, gonna reopen - let's call this one for writing up some basic docs on dep prune, as well as the intent to absorb it back up into ensure.

[carolynvs]

I think this can be closed in favor of the existing issue for the prune documentation: #875?

[sdboyer]

oh, yes! i missed that. thanks 😄