ack/docker-cluster: add fast way to start local docker cluster

[yichengq]

This displays the way to run multiple cfs fast in docker. And this helps
for further development on reconstruct and copy.

for the first part of #82

vagrant@ubuntu-14:~/gopath/src/github.com/c-fs/cfs/hack/docker-cluster$ sudo /home/vagrant/gopath/bin/goreman start
05:41:02 cfs0 | Starting cfs0 on port 5000
05:41:02 cfs1 | Starting cfs1 on port 5001
05:41:02 cfs2 | Starting cfs2 on port 5002
05:41:03 cfs2 | E0724 05:41:03.003147       1 manager.go:220] Failed to start OOM watcher, will not get OOM events: exec: "journalctl": executable file not found in $PATH
05:41:03 cfs0 | E0724 05:41:03.146837       1 manager.go:220] Failed to start OOM watcher, will not get OOM events: exec: "journalctl": executable file not found in $PATH
05:41:03 cfs1 | E0724 05:41:03.175936       1 manager.go:220] Failed to start OOM watcher, will not get OOM events: exec: "journalctl": executable file not found in $PATH
05:41:03 cfs2 | 2015/07/24 05:41:03 [INFO][github.com/c-fs/cfs/server] main.go:36: server: detect docker container "/docker/86b3cdfa68a9600e9142fb157a476bc7a57ae52dd30b9a0a671a2ef3ae335ef6"
05:41:03 cfs2 | 2015/07/24 05:41:03 [INFO][github.com/c-fs/cfs/server] main.go:39: server: starting server...
05:41:03 cfs2 | 2015/07/24 05:41:03 [INFO][github.com/c-fs/cfs/server] main.go:46: server: listening on :15524
05:41:03 cfs2 | 2015/07/24 05:41:03 [INFO][github.com/c-fs/cfs/server] disk_manage.go:27: server: created disk[cfs2_0] at root path[/cfs2_0]
05:41:03 cfs2 | 2015/07/24 05:41:03 [INFO][github.com/c-fs/cfs/server] disk_manage.go:27: server: created disk[cfs2_1] at root path[/cfs2_1]
05:41:03 cfs2 | 2015/07/24 05:41:03 [INFO][github.com/c-fs/cfs/server] main.go:60: server: ready to serve clients
05:41:03 cfs1 | 2015/07/24 05:41:03 [INFO][github.com/c-fs/cfs/server] main.go:36: server: detect docker container "/docker/89958b8f806c27d614ff5cd9eb6a5db08726f190f4c3544151c9aba462bee653"
05:41:03 cfs1 | 2015/07/24 05:41:03 [INFO][github.com/c-fs/cfs/server] main.go:39: server: starting server...
05:41:03 cfs1 | 2015/07/24 05:41:03 [INFO][github.com/c-fs/cfs/server] main.go:46: server: listening on :15524
05:41:03 cfs1 | 2015/07/24 05:41:03 [INFO][github.com/c-fs/cfs/server] disk_manage.go:27: server: created disk[cfs1_0] at root path[/cfs1_0]
05:41:03 cfs1 | 2015/07/24 05:41:03 [INFO][github.com/c-fs/cfs/server] disk_manage.go:27: server: created disk[cfs1_1] at root path[/cfs1_1]
05:41:03 cfs1 | 2015/07/24 05:41:03 [INFO][github.com/c-fs/cfs/server] main.go:60: server: ready to serve clients
05:41:03 cfs0 | 2015/07/24 05:41:03 [INFO][github.com/c-fs/cfs/server] main.go:36: server: detect docker container "/docker/3d4fbab824c373543fe2e6e50006c649469fb2201e55e70971170377440b5974"
05:41:03 cfs0 | 2015/07/24 05:41:03 [INFO][github.com/c-fs/cfs/server] main.go:39: server: starting server...
05:41:03 cfs0 | 2015/07/24 05:41:03 [INFO][github.com/c-fs/cfs/server] main.go:46: server: listening on :15524
05:41:03 cfs0 | 2015/07/24 05:41:03 [INFO][github.com/c-fs/cfs/server] disk_manage.go:27: server: created disk[cfs0_0] at root path[/cfs0_0]
05:41:03 cfs0 | 2015/07/24 05:41:03 [INFO][github.com/c-fs/cfs/server] disk_manage.go:27: server: created disk[cfs0_1] at root path[/cfs0_1]
05:41:03 cfs0 | 2015/07/24 05:41:03 [INFO][github.com/c-fs/cfs/server] main.go:60: server: ready to serve clients
^Cvagrant@ubuntu-14:~/gopath/src/github.com/c-fs/cfs/hack/docker-cluster$ sudo ./cleanup.sh
89958b8f806c
86b3cdfa68a9
3d4fbab824c3
89958b8f806c
86b3cdfa68a9
3d4fbab824c3

[missmayo]

shall we use pkg
github.com/spf13/cobra
for flag parsing here also well for consistent?

[yichengq]

I think we use cobra framework because it faciliates the way to write subcommand. Considering we don't use subcommand in server side, it is fine to use standard flag lib here.

[xiang90]

agreed with @yichengq

[xiang90]

LGTM