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https://github.com/danielsdeleo/knife-boxer

Frictionless Chef Environments via Checksum-Versioned Cookbooks
https://github.com/danielsdeleo/knife-boxer

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Frictionless Chef Environments via Checksum-Versioned Cookbooks

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README 

        
# KNIFE BOXER



Knife Boxer provides a set of plugins for managing cookbooks in an

immutable way and creating sandboxed environments for testing.



## Frictionless Environment Usage



Knife boxer makes environments frictionless. It does this by uploading

cookbooks using version numbers based on checksums of a cookbook's

files. When uploading, you always specify the environment you want the

cookbooks to apply to:



    knife up production cookbooks/redis



This uploads the cookbook with a version number like

"30718453.4494255.188737193" and pins the production environment to this

version. You never need to worry about overwriting this cookbook with a

development version, because the version number is computed from the

cookbook content.



This has a few implications:



1. You have to use environments everywhere. The "_default" environment

   is basically useless if you use this plugin.

2. Your team has to go all-in. This only works if everyone uses it.

3. Version information is stripped from cookbook dependencies, so the

   Chef server can't solve constraints for you. You need to have an

   interoperable set of cookbooks on disk to upload.



In this scheme, version numbers have no relationship to the amount of

change in a cookbook or when it was written. To make this easier to

handle, each cookbook upload writes a log entry in a data bag. You can

search this data bag by environment, cookbook, or username to see what's

changed in your cookbooks and environments.



Knife boxer also makes it easy to create disposable environments the

same way you'd use git branches for development or exploration. When

uploading you can choose to create a new environment or fork an existing

one so that your changes are isolated from other environments. For

example, to create a "my-hacks" environment which is copied from

production with your own edits to the application cookbook:



    knife up -f production my-hacks cookbooks/application



## Commands



* `knife up ENVIRONMENT COOKBOOK_PATHS`: Upload the cookbooks at the

given paths, and update the environment's constraints to match. You can

also fork a given environment or create a new one. This creates a log

entry (using data bags) describing the change.



* `knife log`: Display logs generated by `knife up`. Logs are stored as

data bag items and fetched by search, so there is a delay between

writing them and when they are available. This is very prototype-y.

Filtering features are planned but not implemented. Log output is like

this:



        ID: 20130210191429

          Environment: default

          Updated by: kallistec

          Date: 2013-02-10 11:14:29 -0800

        

          apt 75049083.142609138.113682976 => 58339039.237290627.212044539

        

        ID: 20130209233558

          Environment: default

          Updated by: kallistec

          Date: 2013-02-09 15:35:58 -0800

        

          drupal          Nothing => 44704955.71835109.263707545

          test1           Nothing => 123698944.774444.218245914

          graphite        Nothing => 228126459.170171648.14274816

          no-such-package Nothing => 22792969.162955587.34072117

          xml             Nothing => 157000105.142327922.10318776



* `knife revert UPDATE_ID`: Revert a change to an environment. The

update id is printed when updating or can be found with `knife log`.



## Installation



This is alpha quality code, so it's only distributed via github for now.

Knife only supports a single user plugins directory, so an installation

script is provided to create a shim which will load knife-boxer:



    ruby install.rb



This creates a file `~/.chef/plugins/knife/knife-boxer-shim.rb`. If you

want to uninstall knife-boxer then you need to delete that file.



## Project Goals



This plugin implements as much of [my ideal conception of environments](https://gist.github.com/danielsdeleo/7c55ebe39639928134df)

as is possible without server modifications.



1. Frictionless environments: I want environments to work without

   a bump a version here, change a dependency there dance.

2. Integrated freezing: Related to the above, I don't want to do any

   extra work to ensure that no one stomps an existing cookbook version.

3. Move responsibility for solving cookbook constraints elsewhere: I

   don't need the Chef server to solve the dependency constraints of my

   cookbooks every time chef-client asks for cookbooks. This can be done

   in a different time/place, e.g., with librarian or berkshelf.



## About the Name



* I have a boxer dog. She's awesome.

* The default environments workflow makes me want to punch someone in

  the face.

* Lightweight environment "forking" means everyone on the team can have

  their own sandboxes to test changes with whatever degree of isolation

  is appropriate.



## Errata



There is no way for a knife plugin to atomically mange version

contraints in an environment. Two users uploading at the same time will

stomp each other's changes.