/Chef 12

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


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

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


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


This command has the following syntax:


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.
--audit-mode MODE
Enable audit-mode. Set to audit-only to skip the converge phase of the chef-client run and only perform audits. Possible values: audit-only, disabled, and enabled. Default value: disabled.
-c CONFIG, --config CONFIG
The configuration file to use.
--chef-zero-host HOST
The host on which chef-zero is started.
--chef-zero-port PORT
The port on which chef-zero listens. If a port is not specified—individually, as range of ports, or from the chef_zero.port setting in the client.rb file—the chef-client will scan for ports between 8889-9999 and will pick the first port that is available.
-d SECONDS, --daemonize SECONDS

Run the executable as a daemon. Use SECONDS to specify the number of seconds to wait before the first daemonized chef-client run. SECONDS is set to 0 by default.

This option is only available on machines that run in UNIX or Linux environments. For machines that are running Microsoft Windows that require similar functionality, use the chef-client::service recipe in the chef-client cookbook: https://supermarket.chef.io/cookbooks/chef-client. This will install a chef-client service under Microsoft Windows using the Windows Service Wrapper.

Use to run the chef-client using default settings. This will prevent the normally-associated configuration file from being used. This setting should only be used for testing purposes and should never be used in a production setting.
The name of the environment.
-f, --[no-]fork
Contain the chef-client run in a secondary process with dedicated RAM. When the chef-client run is complete, the RAM is returned to the master process. This option helps ensure that a chef-client uses a steady amount of RAM over time because the master process does not run recipes. This option also helps prevent memory leaks such as those that can be introduced by the code contained within a poorly designed cookbook. Use --no-fork to disable running the chef-client in fork node. Default value: --fork.
-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.

Show formatter output instead of logger output.
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 and --interval values are applied before the chef-client run. Default value: 1800.
-j PATH, --json-attributes PATH

The path to a file that contains JSON data. Used to setup the first client run. For all the future runs with option -i the attributes are expected to be persisted in the chef-server.


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

"run_list": [

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

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


Use this option to set the chef_environment value for a node.


Any environment specified for chef_environment by a JSON file will take precedence over an environment specified by the --environment option when both options are part of the same command.

For example, run the following:

$ chef-client -j /path/to/file.json

where /path/to/file.json is similar to:

  "chef_environment": "pre-production"

This will set the environment for the node to pre-production.

All attributes are normal attributes

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"

Specify a policy

Use this option to use policy files by specifying a JSON file that contains the following settings:

Setting Description
policy_group The name of a policy, as identified by the name setting in a Policyfile.rb file.
policy_name The name of a policy group that exists on the Chef server.

For example:

  "policy_name": "appserver",
  "policy_group": "staging"
-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).
The location of the log file. This is recommended when starting any executable as a daemon. Default value: STDOUT.
--lockfile LOCATION
Use to specify the location of the lock file, which prevents multiple chef-client processes from converging at the same time.
Run the Ohai plugins for name detection and resource/provider selection and no other Ohai plugins. Set to true during integration testing to speed up test cycles.
View colored output. Default setting: --color.
Allows OpenSSL to enforce FIPS-validated security during the chef-client run.
Run chef-zero in socketless mode.
-n NAME, --named-run-list NAME
The run-list associated with a policy file.
-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. This option will not clear the list of cookbooks (and related files) that is cached on the node. This option will not persist node data at the end of the client run.
Run the chef-client only once and cancel interval and splay options.
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.

Use the --profile-ruby option to dump a (large) profiling graph into /var/chef/cache/graph_profile.out. Use the graph output to help identify, and then resolve performance bottlenecks in a chef-client run. This option:

  • Generates a large amount of data about the chef-client run
  • Has a dependency on the ruby-prof gem, which is packaged as part of Chef and the Chef development kit
  • Increases the amount of time required to complete the chef-client run
  • Should not be used in a production environment
Permanently replace the current run-list with the specified run-list items.
-R, --enable-reporting
Enable Reporting, which performs data collection during a chef-client run.
The path to a recipe. For example, if a recipe file is in the current directory, use recipe_file.rb. This is typically used with the --local-mode option.
The location of a recipe when it exists at a URL. Use this option only when the chef-client is run with the --local-mode option.
--run-lock-timeout SECONDS
The amount of time (in seconds) to wait for a chef-client lock file to be deleted. Default value: not set (indefinite). Set to 0 to cause a second chef-client to exit immediately.
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 and --interval values are applied before the chef-client run.
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.

chef-client Lock File

The chef-client uses a lock file to ensure that only one chef-client run is in progress at any time. A lock file is created at the start of the chef-client run and is deleted at the end of the chef-client run. A new chef-client run looks for the presence of a lock file and, if present, will wait for that lock file to be deleted. The location of the lock file can vary by platform.

  • Use the lockfile setting in the client.rb file to specify non-default locations for the lock file. (The default location is typically platform-dependent and is recommended.)
  • Use the run_lock_timeout setting in the client.rb file to specify the amount of time (in seconds) to wait for the lock file associated with an in-progress chef-client run to be deleted.

Run in Local Mode

Local mode is a way to run the chef-client against the chef-repo on a local machine as if it were running against the Chef server. Local mode relies on chef-zero, which acts as a very lightweight instance of the Chef server. chef-zero reads and writes to the chef_repo_path, which allows all commands that normally work against the Chef server to be used against the local chef-repo.

Local mode does not require a configuration file, instead it will look for a directory named /cookbooks and will set chef_repo_path to be just above that. (Local mode will honor the settings in a configuration file, if desired.) If the client.rb file is not found and no configuration file is specified, local mode will search for a knife.rb file.

Local mode will store temporary and cache files under the <chef_repo_path>/.cache directory by default. This allows a normal user to run the chef-client in local mode without requiring root access.

About chef-zero

chef-zero is a very lightweight Chef server that runs in-memory on the local machine. This allows the chef-client to be run against the chef-repo as if it were running against the Chef server. chef-zero was originally a standalone tool; it is enabled from within the chef-client by using the --local-mode option. chef-zero is very useful for quickly testing and validating the behavior of the chef-client, cookbooks, recipes, and run-lists before uploading that data to the actual Chef server.

Use Encrypted Data Bags

A data bag is a global variable that is stored as JSON data and is accessible from a Chef server. A data bag is indexed for searching and can be loaded by a recipe or accessed during a search.

Create an encrypted data bag for use with chef-client local mode

To generate an encrypted data bag item in a JSON file for use when the chef-client is run in local mode (via the --local-mode option), enter:

$ knife data bag from file my_data_bag /path/to/data_bag_item.json -z --secret-file /path/to/encrypted_data_bag_secret

this will create an encrypted JSON file in:


Run in Audit Mode

The chef-client may be run in audit-mode. Use audit-mode to evaluate custom rules—also referred to as audits—that are defined in recipes. audit-mode may be run in the following ways:

  • By itself (i.e. a chef-client run that does not build the resource collection or converge the node)
  • As part of the chef-client run, where audit-mode runs after all resources have been converged on the node

Each audit is authored within a recipe using the control_group and control methods that are part of the Recipe DSL. Recipes that contain audits are added to the run-list, after which they can be processed by the chef-client. Output will appear in the same location as the regular chef-client run (as specified by the log_location setting in the client.rb file).

Finished audits are reported back to the Chef server. From there, audits are sent to the Chef Analytics platform for further analysis, such as rules processing and visibility from the actions web user interface.

Use following option to run the chef-client in audit-mode mode:

--audit-mode MODE
Enable audit-mode. Set to audit-only to skip the converge phase of the chef-client run and only perform audits. Possible values: audit-only, disabled, and enabled. Default value: disabled.

Run in FIPS Mode

Federal Information Processing Standards (FIPS) is a United States government computer security standard that specifies security requirements for cryptography. The current version of the standard is FIPS 140-2. The chef-client can be configured to allow OpenSSL to enforce FIPS-validated security during a chef-client run. This will disable cryptography that is explicitly disallowed in FIPS-validated software, including certain ciphers and hashing algorithms. Any attempt to use any disallowed cryptography will cause the chef-client to throw an exception during a chef-client run.


Chef uses MD5 hashes to uniquely identify files that are stored on the Chef server. MD5 is used only to generate a unique hash identifier and is not used for any cryptographic purpose.

Notes about FIPS:

  • May be enabled for nodes running on Microsoft Windows and Enterprise Linux platforms
  • Should only be enabled for environments that require FIPS 140-2 compliance
  • May not be enabled for any version of the chef-client earlier than 12.8

Bootstrap a node using FIPS

$ knife bootstrap -P vanilla -x root -r 'recipe[apt],recipe[xfs],recipe[vim]' --fips

which shows something similar to:

OpenSSL FIPS 140 mode enabled
... Chef Client finished, 12/12 resources updated in 78.942455583 seconds

Run as a Service

The chef-client can be run as a daemon. Use the chef-client cookbook to configure the chef-client as a daemon. Add the default recipe to a node’s run-list, and then use attributes in that cookbook to configure the behavior of the chef-client. For more information about these configuration options, see the chef-client cookbook repository on github.

When the chef-client is run as a daemon, the following signals may be used:

Use to reconfigure the chef-client.
Use to terminate immediately without waiting for the current chef-client run to finish.
Use to dump a stack trace, and continue to run.
Use to terminate but wait for the current chef-client run to finish, and then exit.
Use to wake up sleeping chef-client and trigger node convergence.

On Microsoft Windows, both the HUP and QUIT signals are not supported.

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.


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


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

Run as Non-root User

In large, distributed organizations the ability to modify the configuration of systems is sometimes segmented across teams, often with varying levels of access to those systems. For example, core application services may be deployed to systems by a central server provisioning team, and then developers on different teams build tooling to support specific applications. In this situation, a developer only requires limited access to machines and only needs to perform the operations that are necessary to deploy tooling for a specific application.

The default configuration of the chef-client assumes that it is run as the root user. This affords the chef-client the greatest flexibility when managing the state of any object. However, the chef-client may be run as a non-root user—i.e. “run as a user with limited system privileges”—which can be useful when the objects on the system are available to other user accounts.

When the chef-client is run as a non-root user the chef-client can perform any action allowed to that user, as long as that action does not also require elevated privileges (such as sudo or pbrun). Attempts to manage any object that requires elevated privileges will result in an error. For example, when the chef-client is run as a non-root user that is unable to create or modify users, the user resource will not work.

Set the Cache Path

To run a chef-client in non-root mode, add the cache_path setting to the client.rb file for the node that will run as the non-root user. Set the value of cache_path to be the home directory for the user that is running the chef-client. For example:

cache_path "~/.chef/cache"


cache_path File.join(File.expand_path("~"), ".chef", "cache")


When running the chef-client using the --local-mode option, ~/.chef/local-mode-cache is the default value for cache_path.

Elevate Commands

Another example of running the chef-client as a non-root user involves using resources to pass sudo commands as as an attribute on the resource. For example, the service resource uses a series of _command attributes (like start_command, stop_command, and so on), the package-based resources use the options attribute, and the script-based resources use the code attribute.

A command can be elevated similar to the following:

service 'apache2' do
  start_command 'sudo /etc/init.d/apache2 start'
  action :start

This approach can work very well on a case-by-case basis. The challenge with this approach is often around managing the size of the /etc/sudoers file.

Run on IBM AIX

The chef-client may now be used to configure nodes that are running on the AIX platform, versions 6.1 (TL6 or higher, recommended) and 7.1 (TL0 SP3 or higher, recommended). The service resource supports starting, stopping, and restarting services that are managed by System Resource Controller (SRC), as well as managing all service states with BSD-based init systems.

System Requirements

The chef-client has the same system requirements on the AIX platform as any other platform, with the following notes:

  • Expand the file system on the AIX platform using chfs or by passing the -X flag to installp to automatically expand the logical partition (LPAR)
  • The EN_US (UTF-8) character set should be installed on the logical partition prior to installing the chef-client

Install the chef-client on the AIX platform

The chef-client is distributed as a Backup File Format (BFF) binary and is installed on the AIX platform using the following command run as a root user:

# installp -aYgd chef-12.0.0-1.powerpc.bff all

Increase system process limits

The out-of-the-box system process limits for maximum process memory size (RSS) and number of open files are typically too low to run the chef-client on a logical partition (LPAR). When the system process limits are too low, the chef-client will not be able to create threads. To increase the system process limits:

  1. Validate that the system process limits have not already been increased.

  2. If they have not been increased, run the following commands as a root user:

    $ chsec -f /etc/security/limits -s default -a "rss=-1"

    and then:

    $ chsec -f /etc/security/limits -s default -a "data=-1"

    and then:

    $ chsec -f /etc/security/limits -s default -a "nofiles=50000"


    The previous commands may be run against the root user, instead of default. For example:

    $ chsec -f /etc/security/limits -s root_user -a "rss=-1"
  3. Reboot the logical partition (LPAR) to apply the updated system process limits.

When the system process limits are too low, an error is returned similar to:

Error Syncing Cookbooks:

Unexpected Error:
ThreadError: can't create Thread: Resource temporarily unavailable

Install the UTF-8 character set

The chef-client uses the EN_US (UTF-8) character set. By default, the AIX base operating system does not include the EN_US (UTF-8) character set and it must be installed prior to installing the chef-client. The EN_US (UTF-8) character set may be installed from the first disc in the AIX media or may be copied from /installp/ppc/*EN_US* to a location on the logical partition (LPAR). This topic assumes this location to be /tmp/rte.

Use smit to install the EN_US (UTF-8) character set. This ensures that any workload partitions (WPARs) also have UTF-8 applied.

Remember to point INPUT device/directory to /tmp/rte when not installing from CD.

  1. From a root shell type:

    # smit lang

    A screen similar to the following is returned:

    Manage Language Environment
    Move cursor to desired item and press Enter.
      Change/Show Primary Language Environment
      Add Additional Language Environments
      Remove Language Environments
      Change/Show Language Hierarchy
      Set User Languages
      Change/Show Applications for a Language
      Convert System Messages and Flat Files
    F1=Help             F2=Refresh          F3=Cancel           F8=Image
    F9=Shell            F10=Exit            Enter=Do
  2. Select Add Additional Language Environments and press Enter. A screen similar to the following is returned:

    Add Additional Language Environments
    Type or select values in entry fields.
    Press Enter AFTER making all desired changes.
                                                            [Entry Fields]
      CULTURAL convention to install                                             +
      LANGUAGE translation to install                                            +
    * INPUT device/directory for software                [/dev/cd0]              +
      EXTEND file systems if space needed?                yes                    +
      WPAR Management
          Perform Operation in Global Environment         yes                    +
          Perform Operation on Detached WPARs             no                     +
              Detached WPAR Names                        [_all_wpars]            +
          Remount Installation Device in WPARs            yes                    +
          Alternate WPAR Installation Device             []
    F1=Help             F2=Refresh          F3=Cancel           F4=List
    F5=Reset            F6=Command          F7=Edit             F8=Image
    F9=Shell            F10=Exit            Enter=Do
  3. Cursor over the first two entries—CULTURAL convention to install and LANGUAGE translation to install—and use F4 to navigate through the list until UTF-8 English (United States) [EN_US] is selected. (EN_US is in capital letters!)

  4. Press Enter to apply and install the language set.


The service resource has the following providers to support the AIX platform:

Long name Short name Notes
Chef::Provider::Service::Aix service The provider that is used with the AIX platforms. Use the service short name to start, stop, and restart services with System Resource Controller (SRC).
Chef::Provider::Service::AixInit service The provider that is used to manage BSD-based init services on AIX.

Enable a service on AIX using the mkitab command

The service resource does not support using the :enable and :disable actions with resources that are managed using System Resource Controller (SRC). This is because System Resource Controller (SRC) does not have a standard mechanism for enabling and disabling services on system boot.

One approach for enabling or disabling services that are managed by System Resource Controller (SRC) is to use the execute resource to invoke mkitab, and then use that command to enable or disable the service.

The following example shows how to install a service:

execute "install #{node['chef_client']['svc_name']} in SRC" do
  command "mkssys -s #{node['chef_client']['svc_name']}
                  -p #{node['chef_client']['bin']}
                  -u root
                  -n 15
                  -f 9
                  -o #{node['chef_client']['log_dir']}/client.log
                  -e #{node['chef_client']['log_dir']}/client.log -a '
                  -i #{node['chef_client']['interval']}
                  -s #{node['chef_client']['splay']}'"
  not_if "lssrc -s #{node['chef_client']['svc_name']}"
  action :run

and then enable it using the mkitab command:

execute "enable #{node['chef_client']['svc_name']}" do
  command "mkitab '#{node['chef_client']['svc_name']}:2:once:/usr/bin/startsrc
                  -s #{node['chef_client']['svc_name']} > /dev/console 2>&1'"
  not_if "lsitab #{node['chef_client']['svc_name']}"

Configuring a Proxy Server

See the proxies documentation for information on how to configure chef-client to use a proxy server.


Run the chef-client

$ sudo chef-client

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

Setting the initial run-list using a JSON file

A node’s initial run-list is specified using a JSON file on the host system. When running the chef-client as an executable, use the -j option to tell the chef-client which JSON file to use. For example:

$ chef-client -j /etc/chef/file.json --environment _default

where file.json is similar to:

  "resolver": {
    "nameservers": [ "" ],
  "run_list": [ "recipe[resolver]" ]

and where _default is the name of the environment that is assigned to the node.


This approach may be used to update normal attributes, but should never be used to update any other attribute type, as all attributes updated using this option are treated as normal attributes.

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