Initial specification of policyfile builder

[danielsdeleo]

Adds a Policyfile.lock Building DSL. The internals are basically complete. We could add a CLI for this, and I think we should eventually, but I'd like to wait on that until we find the proper long-term home for this code (which might not be in ChefDK).

The general design assumptions are:

• There is a local cache for remote cookbooks. The remote cookbooks are expected to not be modified, so that their content checksum and metadata can be trusted.
• cookbooks on the local filesystem (outside of the local cache) are assumed to be "volatile" and metadata will need to be re-checked for each operation. This implies that we may auto-update the lock file on access in some situations (but we can figure what the limitation on this are when we implement the rest of the policy file workflow).
• There is a "git repo discovery" feature that mines data about local git repos for "dev" cookbooks.
• In the future we'll probably need to store the dependency graph inside the lock file to optimize operations like updates. I'll leave that for later because chef-client won't care, it just needs the versions.

[sersut]

Yeah I think this should be default since if you don't have this you potentially don't know if the cookbook you've got is the right one.

[sersut]

One different approach would be to get source types are required parameters separately. E.g.

# cb.source("https://community.getchef.com/api/cookbooks/foo/1.0.0")
# => 
cb.source("https://community.getchef.com/")
cb.version("1.0.0")
# We already have the cookbook name

# cb.source("git://github.com/opscode-cookbooks/bar.git")
# =>
cb.source("git://github.com/opscode-cookbooks/bar.git")
cb.revision("f59ee7a5bca6a4e606b67f7f856b768d847c39bb")

# cb.source("git://github.com/opscode-cookbooks/bar.git")
# =>
cb.source("https://chef-server.example.com/")
cb.version("1.2.3")

Taking this one step further would be to be explicit about the source type [:path, :git, :site, :server] :
especially since differentiation between :server and site is tough:

cb.source(:server, "https://chef-server.example.com/")

cb.source(:site, "https://community.getchef.com/")

[danielsdeleo]

@sersut Keep in mind that source is purely informational at the Policyfile.lock level. The only things required for the upload and later client download to function are:

• Cookbook object IDs. Currently we use a compound primary key of {Name, Version}, what we do when we implement new cookbook artifact storage APIs is TBD.
• The local source of cookbooks to upload.
• The run list.

Everything else is informational and designed to help humans track and understand changes. If given a policyfile.lock diff that shows that the source of a cookbook changed from "https://chef-server.example.com/" to "https://community.getchef.com/" a human can quickly understand the difference.

[sersut]

👍 Party on!!!

I understand things might change in the future but would be nice to have some minimal documentation explaining what we believe these mean:

{
          "version" => identifiers.semver_version,
          "identifier" => identifier,
          "dotted_decimal_identifier" => dotted_decimal_identifier,
          "cache_key" => cache_key,
          "origin" => origin
}

[danielsdeleo]

@sersut where? In the tests?

[sersut]

@danielsdeleo maybe here?

[danielsdeleo]

That works.