chef-client (executable)

A chef-client is an agent that runs locally on every node that is under management by Chef. When a chef-client is run, it will perform all of the steps that are required to bring the node into the expected state, including:

  • Registering and authenticating the node with the Chef server
  • Building the node object
  • Synchronizing cookbooks
  • Compiling the resource collection by loading each of the required cookbooks, including recipes, attributes, and all other dependencies
  • Taking the appropriate and required actions to configure the node
  • Looking for exceptions and notifications, handling each as required

Note

The chef-client executable can be run as a daemon.

The chef-client executable is run as a command-line tool.

Note

A client.rb file is used to specify the configuration details for the chef-client.

  • This file is loaded every time this executable is run
  • On UNIX- and Linux-based machines, the default location for this file is /etc/chef/client.rb; on Microsoft Windows machines, the default location for this file is C:\chef\client.rb; use the --config option from the command line to change this location
  • This file is not created by default
  • When a client.rb file is present in the default location, the settings contained within that client.rb file will override the default configuration settings

Syntax

This command has the following syntax:

$ chef-client OPTION VALUE OPTION VALUE ...

Options

This command has the following options:

-A, --fatal-windows-admin-check
Cause a chef-client run to fail when the chef-client does not have administrator privileges in Microsoft Windows.
-c CONFIG, --config CONFIG
The configuration file to use.
--chef-zero-port PORT
The port on which chef-zero listens.
-F FORMAT, --format FORMAT

The output format: doc (default) or min.

  • Use doc to print the progress of the chef-client run using full strings that display a summary of updates as they occur.
  • Use min to print the progress of the chef-client run using single characters.

A summary of updates is printed at the end of the chef-client run. A dot (.) is printed for events that do not have meaningful status information, such as loading a file or synchronizing a cookbook. For resources, a dot (.) is printed when the resource is up to date, an S is printed when the resource is skipped by not_if or only_if, and a U is printed when the resource is updated.

Other formatting options are available when those formatters are configured in the client.rb file using the add_formatter option.

--force-formatter
Show formatter output instead of logger output.
--force-logger
Show logger output instead of formatter output.
-g GROUP, --group GROUP
The name of the group that owns a process. This is required when starting any executable as a daemon.
-h, --help
Show help for the command.
-i SECONDS, --interval SECONDS
The frequency (in seconds) at which the chef-client runs. When the chef-client is run at intervals, --splay values are applied first, then the chef-client run occurs, and then --interval values are applied. Default value: 1800.
-j PATH, --json-attributes PATH

The path to a file that contains JSON data.

Use this option to define a run_list object. For example, a JSON file similar to:

"run_list": [
  "recipe[base]",
  "recipe[foo]",
  "recipe[bar]",
  "role[webserver]"
],

may be used by running chef-client -j path/to/file.json.

In certain situations this option may be used to update normal attributes.

Warning

Any other attribute type that is contained in this JSON file will be treated as a normal attribute. For example, attempting to update override attributes using the -j option:

{
  "name": "dev-99",
  "description": "Install some stuff",
  "override_attributes": {
    "apptastic": {
      "enable_apptastic": "false",
      "apptastic_tier_name": "dev-99.bomb.com"
    }
  }
}

will result in a node object similar to:

{
  "name": "maybe-dev-99",
  "normal": {
  "name": "dev-99",
    "description": "Install some stuff",
    "override_attributes": {
      "apptastic": {
        "enable_apptastic": "false",
        "apptastic_tier_name": "dev-99.bomb.com"
      }
    }
  }
}
-k KEY_FILE, --client_key KEY_FILE
The location of the file that contains the client key. Default value: /etc/chef/client.pem.
-K KEY_FILE, --validation_key KEY_FILE
The location of the file that contains the key used when a chef-client is registered with a Chef server. A validation key is signed using the validation_client_name for authentication. Default value: /etc/chef/validation.pem.
-l LEVEL, --log_level LEVEL
The level of logging to be stored in a log file. Possible levels: :auto (default), debug, info, warn, error, or fatal. Default value: warn (when a terminal is available) or info (when a terminal is not available).
-L LOGLOCATION, --logfile LOGLOCATION
The location of the log file. This is recommended when starting any executable as a daemon. Default value: STDOUT.
--[no-]color
View colored output. Default setting: --color.
-N NODE_NAME, --node-name NODE_NAME
The name of the node.
-o RUN_LIST_ITEM, --override-runlist RUN_LIST_ITEM

Replace the current run-list with the specified items.

Note

This option will clear the list of cookbooks (and related files) that is cached on the node. (Starting in chef-client 12.0, this option will not clear the list of cookbooks.)

--once
Run the chef-client only once and cancel interval and splay options.
-P PID_FILE, --pid PID_FILE
The location in which a process identification number (pid) is saved. An executable, when started as a daemon, writes the pid to the specified file. Default value: /tmp/name-of-executable.pid.
-R, --enable-reporting
Enable Reporting, which performs data collection during a chef-client run.
-s SECONDS, --splay SECONDS
A random number between zero and splay that is added to interval. Use splay to help balance the load on the Chef server by ensuring that many chef-client runs are not occuring at the same interval. When the chef-client is run at intervals, --splay values are applied first, then the chef-client run occurs, and then --interval values are applied.
-S CHEF_SERVER_URL, --server CHEF_SERVER_URL
The URL for the Chef server.
-u USER, --user USER
The user that owns a process. This is required when starting any executable as a daemon.
-v, --version
The version of the chef-client.
-W, --why-run
Run the executable in why-run mode, which is a type of chef-client run that does everything except modify the system. Use why-run mode to understand why the chef-client makes the decisions that it makes and to learn more about the current and proposed state of the system.
-z, --local-mode
Run the chef-client in local mode. This allows all commands that work against the Chef server to also work against the local chef-repo.

Run with Elevated Privileges

The chef-client may need to be run with elevated privileges in order to get a recipe to converge correctly. On UNIX and UNIX-like operating systems this can be done by running the command as root. On Microsoft Windows this can be done by running the command prompt as an administrator.

Linux

On Linux, the following error sometimes occurs when the permissions used to run the chef-client are incorrect:

$ chef-client
[Tue, 29 Nov 2015 19:46:17 -0800] INFO: *** Chef 12.X.X ***
[Tue, 29 Nov 2015 19:46:18 -0800] WARN: Failed to read the private key /etc/chef/client.pem: #<Errno::EACCES: Permission denied - /etc/chef/client.pem>

This can be resolved by running the command as root. There are a few ways this can be done:

  • Log in as root and then run the chef-client

  • Use su to become the root user, and then run the chef-client. For example:

    $ su
    

    and then:

    $ chef-client
    
  • Use the sudo utility

    $ sudo chef-client
    
  • Give a user access to read /etc/chef and also the files accessed by the chef-client. This requires super user privileges and, as such, is not a recommended approach

Windows

On Microsoft Windows, running without elevated privileges (when they are necessary) is an issue that fails silently. It will appear that the chef-client completed its run successfully, but the changes will not have been made. When this occurs, do one of the following to run the chef-client as the administrator:

  • Log in to the administrator account. (This is not the same as an account in the administrator’s security group.)

  • Run the chef-client process from the administrator account while being logged into another account. Run the following command:

    $ runas /user:Administrator "cmd /C chef-client"
    

    This will prompt for the administrator account password.

  • Open a command prompt by right-clicking on the command prompt application, and then selecting Run as administrator. After the command window opens, the chef-client can be run as the administrator

Examples

Start a run when the chef-client is running as a daemon

A chef-client that is running as a daemon can be woken up and started by sending the process a SIGUSR1. For example, to trigger a chef-client run on a machine running Linux:

$ sudo killall -USR1 chef-client

Start a chef-client run manually

$ ps auxw|grep chef-client

to return something like:

root           66066   0.9  0.0  2488880    264 s001  S+   10:26AM   0:03.05
/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/bin/ruby /usr/bin/chef-client -i 3600 -s 20

and then enter:

$ sudo kill -USR1 66066