ohai (executable)
ohai
is the command-line interface for Ohai, a tool that is used to
detect attributes on a node, and then provide these attributes to Chef
Infra Client at the start of every Chef Infra Client run.
Options
This command has the following syntax:
ohai OPTION
This tool has the following options:
ATTRIBUTE_NAME ATTRIBUTE NAME ...
Use to have Ohai show only output for named attributes. To address attributes deeper in the tree, use a
/
delimiter between each level. For example:memory/free
.-c CONFIG
,--config CONFIG
The path to a configuration file to use. For example:
/etc/ohai/config.rb
.-d DIRECTORY
,--directory DIRECTORY
The directory in which additional Ohai plugins are located. For example:
/my/extra/plugins
.-h
,--help
Show help for the command.
-l LEVEL
,--log_level LEVEL
The level of logging to be stored in a log file.
-L LOGLOCATION
,--logfile LOGLOCATION
The location of the log file.
-v
,--version
The version of Ohai.
Examples
The following examples show how to use the Ohai command-line tool:
Query for a specific attribute
Pass an attribute as an argument to ohai
to get the value of that attribute. For example:
ohai os
This fetches the value of Chef Infra’s node data at node['os']
and returns something like:
[
"linux"
]
To query for an attribute deeper in the tree, use a forward slash (/
) as a
delimiter. For example, to query for free memory, run:
ohai memory/free
Run a plugin independently of a Chef Infra Client run
An Ohai plugin can be run independently of a Chef Infra Client run.
First, ensure that the plugin is located in the /plugins
directory and
then use the -f
option when running Ohai from the command line. For
example, a plugin named sl_installed
may look like the following:
Ohai.plugin(:Sl) do
provides "sl"
collect_data(:default) do
sl Mash.new
if ::File.exist?("/usr/games/sl")
sl[:installed] = true
else
sl[:installed] = false
end
# sl[:installed] = ::File.exist?("/usr/games/sl")
end
end
To run that plugin from the command line, use the following command:
ohai --directory /path/to/directory sl
The command will return something similar to:
{
"sl": {
"installed": true
}
}