[chef] Re: Re: Place file only once per version

[Russ Lavoie < >]

An option is to have chef lay down a versioned file and symlink the versioned file to a name the application is expecting.

default['file_version'] = 1.2

template "file-#{node[file_version]}.txt" do

  source "file"

  ...

  ...

end

link "/path/to/source/file-#{node[file_version]}.txt" do

  to "/path/to/expected/by/app/file

end

Then you can unlink the previous version in a similar way.

Hope that helps a bit.

---

From: " " < >
To:
Sent: Thursday, August 15, 2013 3:19 PM
Subject: [chef] Re: Place file only once per version

Hi Mike,

I only need the file to be placed once per version a process outside chef moves this file to a working location and removes it when done. But if the file was to be created again it would trigger the same process again.

This is why I need only place it once per unique checksum. It's not a big deal to change the outside process just time consuming. I think its an option to only create the file once per checksum on the chef side too.

Hope that makes sense.

On 15 Aug 2013, at 18:46, Mike < " target="_blank" href="mailto: "> > wrote:

I guess I'm not understanding what a "unique version" of a file is.

If I modify file 'foo', and put it in my cookbook, then the checksum will differ from the in-place file on the target node, and be placed on disk with `action :create`.

If I then modify the file on disk, then I've changed the checksum locally, and Chef will clobber my change.

You may want to adopt a flow where you on-server modifications (which is an interesting use-case, please elaborate) are done to a copy of your Chef-goverend file.

-M

On Thu, Aug 15, 2013 at 1:42 PM, Damien Roche < " target="_blank" href="mailto: "> > wrote:

The file only needs to be placed once per unique version of the file and is moved modified outside chef control.

On 15 Aug 2013 18:39, "Mike" < " target="_blank" href="mailto: "> > wrote:

Even better:

cookbook_file "foo" do

  action :create_if_missing

end

Boom.

-M

On Thu, Aug 15, 2013 at 1:23 PM, Andrew Gross < " target="_blank" href="mailto: "> > wrote:

Whats wrong with

cookbook_file "foo" do

  action :create

  not_if { ::File.exists?("foo") }

end

On Thu, Aug 15, 2013 at 12:44 PM, Ranjib Dey < " target="_blank" href="mailto: "> > wrote:

oops , forgot share the reference
[1] https://github.com/opscode/chef/blob/master/lib/chef/mixin/checksum.rb

On Thu, Aug 15, 2013 at 9:43 AM, Ranjib Dey < " target="_blank" href="mailto: "> > wrote:

well, you can do that using ruby stdlib, as well as low level chef api (that chef uses to make file/template/cookbookfile/remote_file [1] idempotent). But why you want to do it? If you are doing it
inside a recipe, probably its a bad idea, consider pushing them inside providers or libraries

On Thu, Aug 15, 2013 at 9:24 AM, < " target="_blank" href="mailto: "> > wrote:

Is it possible to get a checksum of a cookbook file and store this in the attribute?

require 'Digest'

cb_filename = ? 

if node.attribute['staged_checksum'] == Digest::SHA2.file(File.new(cb_filename))
	Chef::Log.info("Already been staged")
else
	Chef::Log.info("Update staging")

	node.attribute['staged_checksum'] = Digest::SHA2.file(File.new(cb_filename))

end

On 15 Aug 2013, at 11:40, Ranjib Dey < " target="_blank" href="mailto: "> > wrote:

inside a recipe

if node.attribute?('bar')

  Chef::Log.info('already run')

else

  ruby_block 'set_attribute' do

    block do

      nod.set['foo']='bar'

    end

  end

   file '/foo/bar' do
     content "foobar"
   end

end

On Thu, Aug 15, 2013 at 3:20 AM, < " target="_blank" href="mailto: "> > wrote:

Hello,

Would would be the best way to only place a file once per cookbook version. It's modified and removed outside chef.

Regards
D.