[chef] Re: Re: Re: Re: Re: Re: Re: Re: attributes inheritance

[Cassiano Leal < >]

Nice article. I’m a Ruby dev, so it didn’t really present me with anything new, but it’s got great information summarised in a nice way.

I use ||= all the time when programming in Ruby. It’s a great shortcut for memoisation and some logical operations.

The article is a great reminder that you need to understand how it works before using it everywhere, though. :)

--

Cassiano Leal

http://cassianoleal.com

http://twitter.com/cassianoleal

On July 24, 2013 at 03:19:30, steve . ( ) wrote:

When I started seeing people using ||= (pipe-pipe-equals), I thought it was the coolest thing since:

variable = logical statement ? a : b

But it would get funny sometimes and then I came across this article, which totally melted my brain:

http://www.rubyinside.com/what-rubys-double-pipe-or-equals-really-does-5488.html

Since then, I have (grudgingly) developed a new appreciation for set_unless.

On Tue, Jul 23, 2013 at 12:31 PM, Cassiano Leal < " target="_blank"> > wrote:

I see. So Dorian’s problem would probably be best solved by using

node.normal[:myapp][:part1][:conf] = “XXX1” unless node[:myapp][:part1][:conf]

Right?

--

Cassiano Leal

http://cassianoleal.com

http://twitter.com/cassianoleal

On July 23, 2013 at 09:56:38, Sean OMeara ( " target="_blank"> ) wrote:

chef-shell will free your mind...

$ chef-shell -s

chef > recipe_mode

chef:recipe > node.default['noxexistent'].class

 => Chef::Node::VividMash

When you access an attribute that does not exist from a recipe, it returns as an empty Chef::Node::VividMash object, not nil.

This is why your 'or' statement is failing =)

Some other trivia: 'node.set' is the same as 'node.normal'.

chef:recipe > node.default['foo'] = "bar"

 => "bar"

chef:recipe > node['foo']

 => "bar"

chef:recipe > node.normal['foo'] = "baz"

 => "baz"

chef:recipe > node['foo']

 => "baz"

chef:recipe > node.override['foo'] = "biz"

 => "biz"

chef:recipe > node['foo']

 => "biz"

Yet, all three are actually persisted on the node object

chef:recipe > node.default['foo']

 => "bar"

chef:recipe > node.normal['foo']

 => "baz"

chef:recipe > node.override['foo']

 => "biz"

The chef-client only consumes the one with the highest precedence.

-s

On Tue, Jul 23, 2013 at 8:16 AM, Cassiano Leal < " target="_blank"> > wrote:

I don’t think that’ll work if the default has been set.

What I mean is, say you have:

node.default[:myapp][:part1][:conf] = ‘XXX’

node.set[:myapp][:part1][:conf] ||= ‘XXX1’

This will probably set node[:myapp][:part1][:conf] to ‘XXX1’, since node.set[:myapp][:part1][:conf] was nil when the ||= operator kicked in.

I might be wrong and Chef might be doing some sourcery behind the scenes, but taking only Ruby into account, it wouldn’t work.

--

Cassiano Leal

http://cassianoleal.com

http://twitter.com/cassianoleal

On July 23, 2013 at 05:21:59, Dorian Jaminais ( " target="_blank"> ) wrote:

@Josiah : Thanks for the tip, I didn't know about the ||= operator.

I was looking for a way to do that using the attribute files.

Based on your response, my new work around is to define the component's attributes in two different hashes and have them merge into the default one.

Thanks

2013/7/23 Josiah Kiehl < " target="_blank"> >

I would set this in the component's recipe:

node.normal[:myapp][:part1][:conf] ||= "XXX1"

||= will only set the attribute if the attribute has not yet been set.

On Mon, Jul 22, 2013 at 5:08 PM, Daniel DeLeo < " target="_blank"> > wrote:

On Monday, July 22, 2013 at 10:15 AM, Dorian Jaminais wrote:

Ohai Chefs !

Is there a way in an attribute file to reuse attributes from another file ?

Here is my use case :

I have an application split in two components, each requiring its configuration.

Most of thetime the configuration of both will be identical but this may not be always true.

For this reason I'd like to define 'default' attributes in the default attribute file and then have one attribute file per part of my application. Atribute would be organized this way :

default.rb

  default["myapp"]["conf"] = "XXX"

  default["myapp"]["truc"] = "YYY"
part1.rb
  default["myapp"]["part1"]["conf"] = "XXX1"
  #default["myapp"]["part1"]["truc"] = "YYY" < I want it to default to this value when not explicitly set
part2.rb
  default["myapp"]["part2"]["conf"] = "XXX2"

Is there a way to achieve this ?

At the moment I am using global variable to pass information from one file to the other but this seams ugly to me.

Split the shared part out into another cookbook? 

-- 

Daniel DeLeo

--

Dorian JAMINAIS

System Administrator
+33 6 95 10 95 37