[chef] Re: Re: Re: RE: How to check whether a package is installed ?

[Jesse Hu < >]

Thanks Noah. Actually I want to do something before the service is going to be started (or the package is going to be installed), if the service is already started, I will do nothing. So your code is not what I want.

Thanks
Jesse Hu | Project Serengeti 

---

Noah Kantrowitz wrote On Fri, 11 Oct 2013 22:48:41 -0700 :

" type="cite">

Instead of your example you could do it idemopotently and asset the desired state. Something more like

if node['should_mysrv']
  package 'mypkg' do
    action :install
  end

  service 'mysvr' do
    action [:enable, :start]
  end

  ruby_block do
    code do
      do_work
    end
  end
else
  package 'mypkg' do
    action :remove
  end

  service 'mysvr' do
    action [:disable, :stop]
  end
end

Rather than reacting to state, that is enforcing and updating state.

--Noah

On Oct 11, 2013, at 3:27 AM, Hui Hu 
 
 "><
 > wrote:

Thanks Kevin.  Scenario 2 is what I want.  How to use Ohai automatic attribute to check whether a pacakge is installed or a service is running ?  

What I want is some code like this :

do-work if package('mypkg').installed? 
do-work if service('mysvr').running? 

Thanks
Jesse Hu,  Project Serengeti


2013/10/10 Kevin Keane Subscription 
 
 "><
 >
What exactly are you trying to accomplish? There are two different scenarios I can think of, and you can address them in two different ways.

Scenario 1: you want to install MySQL, and then perform another action. In that case, you would simply use the package resource, which would then notify your execute resource. In that case, your actions will only execute once right after the package gets installed.
Scenario 2: you want to execute your action only on those servers that already have MySQL installed. In this case, the generic solution would be to use an automatic attribute that Chef automatically populates at the beginning of the chef run (actually, Ohai does the populating). In that case, your actions will be executed on every single Chef run.
The first scenario is probably closer to what Chef is intended for. The second scenario means that your action isn't idempotent as Chef expects.


Kevin Keane

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-----Original message-----
From: Hui Hu 
 
 "><
 >
Sent: Thursday 10th October 2013 0:17
To: 
 
 ">
 
Subject: [chef] How to check whether a package is installed ?

Hi Chef,

Is there a simple chef way to check whether a package is installed or a service is running ?

For example, I want to write some code like this :

do-work if package('mypkg').installed? 
do-work if service('mysvr').running? 

I know we can do it by the code below, but it's bind to the specific platform. What I need is a platform independent way.

execute "..." do
  only_if "rpm -q mypkg"
  only_if "service mysvr status"
end

Thanks
Jesse Hu,  Project Serengeti