etcdctlv3: use spf13/cobra for cli interface

[gyuho]

/cc @jonboulle @xiang90

Reference: https://github.com/coreos/rkt/blob/master/rkt/rkt.go

This replaces codegansta/cli with spf13/cobra according to
https://github.com/coreos/docs/blob/master/golang/README.md#cli.

Here's the sample output:

./etcdctlv3 -h
NAME:
    etcdctlv3 - A simple command line client for etcd3.

USAGE:
    etcdctlv3

VERSION:
    2.3.0-alpha.0+git

COMMANDS:
    range       Range gets the keys in the range from the store.
    put     Put puts the given key into the store.
    delete-range    DeleteRange deletes the given range from the store.
    txn     Txn processes all the requests in one transaction.
    compaction  Compaction compacts the event history in etcd.
    watch       Watch watches the events happening or happened.
    version     Print the version of etcd.
    help        Help about any command

OPTIONS:
      --endpoint="127.0.0.1:2378"   gRPC endpoint

[philips]

The biggest problem is we will break every single user that is using a
single - long arg vs a -- long arg. How do we fix that?

On Tue, Nov 24, 2015 at 10:12 PM Gyu-Ho Lee notifications@github.com
wrote:

updated error handling like etcdctl package:

fmt.Fprintln(os.Stderr, err.Error())
os.Exit(ExitCode)

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#3922 (comment).

[gyuho]

@philips good point. I was thinking only replacing the etcdctl* with cobra because they are already in codegansta/cli which uses --long and -short style.

Etcdmain is written with standard flag package and supports both single and double dash, so there is no reason to change that I think.

Thanks!

[philips]

I don't mind changing libraries, we just can't break etcd's flags.

On Wed, Nov 25, 2015 at 7:30 AM Gyu-Ho Lee notifications@github.com wrote:

@philips https://github.com/philips good point. I was thinking only
replacing the etcdctl* with cobra because they are already in
codegansta/cli which uses --long and -short style.

Etcdmain is written with standard flag package and supports both single
and double dash, so there is no reason to change that I think.

Thanks!

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#3922 (comment).

[xiang90]

@gyuho @philips This is just for etcdctlv3, right? We can try whatever we want there at least for now... But what is the motivation for this experiment?

[gyuho]

@xiang90 yeah this is ONLY for etcdctl packages. And this is partially for #3901. I have code for etcdctl as well but wanted this approved first. Thanks!

[xiang90]

@gyuho Well... There is also the current etcdctl not only etcdctlv3

[gyuho]

You are right. I was going to split the PRs because etcdctl is much longer. I think if we switch, we can finish migrating etcdctlv3 with godep and work on etcdctl.

What do you think?

[xiang90]

@gyuho For #3901, we can fix the cli lib we are using. Switching to cobra breaks some flag convention for etcdctl if I remember correctly.

[gyuho]

Fair enough. I don't mind dropping this PR :)
Xiang do you remember what exactly was breaking with cobra? Flag parsing is straightforward so it shouldn't break anything I believe. Thanks!

[jonboulle]

We're not concerned about breaking etcdctlv3 CLI compatibility are we?

[xiang90]

@jonboulle no we are not

@gyuho check this #2892 (comment)

[xiang90]

@gyuho OK. So probably here is what we should do:

keep etcdctl the same.
Use cobra for future command line tools: etcdctl3, etcdbench.

[xiang90]

godep this

[gyuho]

Got it. Thanks!

[gyuho]

@xiang90 I fixed as you suggested with godep dependencies.

Please let me know if you have any feedback. Happy Thanksgiving all!

[xiang90]

@gyuho We need to separate the godep to another commit for easy review.

[gyuho]

Sure! I will separate when I get home. And cobra supports string slice.
Should we chnage?

Sincerely,
Gyu-Ho Lee
On Nov 25, 2015 12:46, "Xiang Li" notifications@github.com wrote:

@gyuho https://github.com/gyuho We need to separate the godep to
another commit for easy review.

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#3922 (comment).

[xiang90]

@gyuho Do not worry. Take your time. Ideally we can make the change. But we can do it in another pr too.

[gyuho]

@xiang90 Just split this into two commits. Please take a look again.

Agree. We can migrate this to cobra first and then figure out how to handle endpoint
in string or string slice.

Thanks!

[gyuho]

@xiang90 Thanks for review.

I pushed some updates:

1. Remove ErrorTxnMalformed and changed it to ErrorInvalidInput
2. Improve error message for bad arguments
3. Fixes some wrong error code

Please take a look again. And let me know if you find anything wrong.

[xiang90]

LGTM

[gyuho]

Thanks!