CLI extensions - playbooks

[chungers]

New CLI extensions called 'Playbooks' allow user to package and define sets of templates and scripts and make the package available in the CLI as new subcommands and flags. This complements the existing local extension mechanism of files/ directories by allowing 'playbooks' to be remote URL resources. Currently the resource URL understand https/http/file resources but in the future we will add other protocols such as git or docker images.

A new command has been added: infrakit playbook add | rm | ls
This command is used to add new playbooks. For example:

infrakit playbook add testdata file://$(pwd)/pkg/cli/remote/testdata/index.ikm

Adds the playbook called testdata:

infrakit -h

Available Commands:
.... # other entries 
 group         Access group plugin
  info          print plugin info
  instance      Access instance plugin
  manager       Access the manager
  metadata      Access metadata exposed by infrakit plugins
  playbook      Manage playbooks
  plugin        Manage plugins
  resource      Access resource plugin
  template      Render an infrakit template at given url.  If url is '-', read from stdin
  testdata      testdata  <=== added here
  util          Utilties
  version       Print build version information

Now remove the playbook:

infrakit playbook rm testdata

Signed-off-by: David Chung david.chung@docker.com

[GordonTheTurtle]

Please sign your commits following these rules:
https://github.com/docker/docker/blob/master/CONTRIBUTING.md#sign-your-work
The easiest way to do this is to amend the last commit:

$ git clone -b "gcp4" git@github.com:chungers/infrakit.git somewhere
$ cd somewhere
$ git rebase -i HEAD~842353657192
editor opens
change each 'pick' to 'edit'
save the file and quit
$ git commit --amend -s --no-edit
$ git rebase --continue # and repeat the amend for each commit
$ git push -f

Amending updates the existing PR. You DO NOT need to open a new one.

[codecov]

Codecov Report

Merging #468 into master will decrease coverage by 0.08%.
The diff coverage is 63.38%.

@@            Coverage Diff             @@
##           master     #468      +/-   ##
==========================================
- Coverage   68.33%   68.25%   -0.09%     
==========================================
  Files          68       69       +1     
  Lines        4084     4152      +68     
==========================================
+ Hits         2791     2834      +43     
- Misses       1047     1063      +16     
- Partials      246      255       +9

Impacted Files	Coverage Δ
pkg/template/util.go	63.63% <100%> (ø)	⬆️
pkg/template/funcs.go	67.77% <50%> (ø)	⬆️
pkg/cli/remote/remote.go	63.23% <63.23%> (ø)

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[YujiOshima]

@chungers This is cool extension. I will try this!
Since playbook is a new concept, We need Documents.
How about adding at least the description in this PR to cli's README as well?

[chungers]

@YujiOshima - thanks. I am doing a little bit of code cleanup. Docs and examples coming soon!