Exploring "Infrastructure as code" with Opscode Chef Part 5 (using local mode & more on OHAI)

Using local mode:

In case we want to bypass the chef server & workstation all together for some reason then we can do that as well. Chef client's local mode allows us to apply a locally created recipe without communicating with the chef server or workstation.
Here's a demo:

On the client, create chef-repo directory & inside that directory create the recipe file:

 mkdir chef-repo
[sahil@cclient1 ~]$ cd chef-repo/
[sahil@cclient1 chef-repo]$ vi hello.rb
hello world[sahil@cclient1 chef-repo]$ cat hello.rb
file '/tmp/motd' do
  content 'hello world'
end
[sahil@cclient1 chef-repo]$

Now to apply the recipe, run chef client in local mode:

[sahil@cclient1 chef-repo]$ chef-client --local-mode hello.rb
[2016-11-06T06:04:48-05:00] WARN: No config file found or specified on command line, using command line options.
[2016-11-06T06:04:48-05:00] WARN: No cookbooks directory found at or above current directory.  Assuming /home/sahil/chef-repo.
Starting Chef Client, version 12.15.19
resolving cookbooks for run list: []
Synchronizing Cookbooks:
Installing Cookbook Gems:
Compiling Cookbooks...
[2016-11-06T06:04:50-05:00] WARN: Node cclient1 has an empty run list.
Converging 1 resources
Recipe: @recipe_files::/home/sahil/chef-repo/hello.rb
  * file[/tmp/motd] action create
    - create new file /tmp/motd
    - update content in file /tmp/motd from none to b94d27
    --- /tmp/motd       2016-11-06 06:04:50.389511251 -0500
    +++ /tmp/.chef-motd20161106-2861-1d6cw4j    2016-11-06 06:04:50.389511251 -0500
    @@ -1 +1,2 @@
    +hello world
    - restore selinux security context

Running handlers:
Running handlers complete
Chef Client finished, 1/1 resources updated in 01 seconds


Let's verify that the file has been created:

[sahil@cclient1 chef-repo]$ cat /tmp/motd
hello world[sahil@cclient1 chef-repo]$ 


Viewing information collected by OHAI:

As mentioned earlier, OHAI collects a lot of information in JSON format. You can check this information from the chef server GUI by selecting the node & then clicking on the attributes section. You can also check this information locally by just typing ohai command on the client node.

Here is a snippet of the output:

[root@cclient1 ~]# ohai | more
{
  "cpu": {
    "0": {
      "vendor_id": "GenuineIntel",
      "family": "6",
      "model": "60",
      "model_name": "Intel(R) Core(TM) i5-4440 CPU @ 3.10GHz",
      "stepping": "3",
      "mhz": "3092.833",
      "cache_size": "6144 KB",
      "physical_id": "0",
      "core_id": "0",
      "cores": "1",

      "flags": [
--------------------------------------------------------------------------------------
--------------------------------------------------------------------------------------

We can also view the information about a node gathered by OHAI from the chef workstation:

[sahil@cwork recipes]$ sudo knife node show mychefnode -l | more
Node Name:   mychefnode
Environment: _default
FQDN:        cclient1
IP:          192.168.44.102
Run List:    recipe[apache::addscreen], recipe[apache]
Roles:
Recipes:     apache, apache::default, apache::addscreen
Platform:    centos 7.0.1406
Tags:
Attributes:
tags:

Default Attributes:

Override Attributes:

Automatic Attributes (Ohai Data):
block_device:
  dm-0:
    logical_block_size:  512
    physical_block_size: 512
    removable:           0
    rotational:          1
    size:                2097152
  dm-1:
    logical_block_size:  512
    physical_block_size: 512
    removable:           0
    rotational:          1
    size:                17842176
------------------------------------------------------------------------------------------
------------------------------------------------------------------------------------------

From the chef workstation we can also query to a particular attribute belonging to a node:

[sahil@cwork recipes]$ sudo knife node show mychefnode -a name
mychefnode:
  name: mychefnode

We can also run a key value search on chef solr using the knife utility since all information gathered by OHAI is available for searching & indexing at the chef server.

[sahil@cwork recipes]$ sudo knife search node "platform:centos" -a name
1 items found

mychefnode:
  name: mychefnode