user resource¶
Use the user resource to add users, update existing users, remove users, and to lock/unlock user passwords.
Note
System attributes are collected by Ohai at the start of every chef-client run. By design, the actions available to the user resource are processed after the start of the chef-client run. This means that system attributes added or modified by the user resource during the chef-client run must be reloaded before they can be available to the chef-client. These system attributes can be reloaded in two ways: by picking up the values at the start of the (next) chef-client run or by using the ohai resource to reload the system attributes during the current chef-client run.
Syntax¶
A user resource block manages users on a node:
user 'a user' do
comment 'A random user'
uid '1234'
gid '1234'
home '/home/random'
shell '/bin/bash'
password '$1$JJsvHslasdfjVEroftprNn4JHtDi'
end
The full syntax for all of the properties that are available to the user resource is:
user 'name' do
comment String
force true, false # see description
gid String, Integer
home String
iterations Integer
manage_home true, false
non_unique true, false
notifies # see description
password String
salt String
shell String
subscribes # see description
system true, false
uid String, Integer
username String # defaults to 'name' if not specified
action Symbol # defaults to :create if not specified
end
where
user
is the resourcename
is the name of the resource blockaction
identifies the steps the chef-client will take to bring the node into the desired statecomment
,force
,gid
,home
,iterations
,manage_home
,non_unique
,password
,salt
,shell
,system
,uid
, andusername
are properties of this resource, with the Ruby type shown. See “Properties” section below for more information about all of the properties that may be used with this resource.
Actions¶
This resource has the following actions:
:create
- Default. Create a user with given properties. If a user already exists (but does not match), update that user to match.
:lock
- Lock a user’s password.
:manage
- Manage an existing user. This action does nothing if the user does not exist.
:modify
- Modify an existing user. This action raises an exception if the user does not exist.
:nothing
- Define this resource block to do nothing until notified by another resource to take action. When this resource is notified, this resource block is either run immediately or it is queued up to be run at the end of the Chef Client run.
:remove
- Remove a user.
:unlock
- Unlock a user’s password.
Properties¶
This resource has the following properties:
comment
Ruby Type: String
One (or more) comments about the user.
force
Ruby Type: true, false
Force the removal of a user. May be used only with the
:remove
action.Warning
Using this property may leave the system in an inconsistent state. For example, a user account will be removed even if the user is logged in. A user’s home directory will be removed, even if that directory is shared by multiple users.
gid
Ruby Type: String, Integer
The identifier for the group. This property was previously named
group
and both continue to function.home
Ruby Type: String
The location of the home directory.
ignore_failure
Ruby Type: true, false | Default Value:
false
Continue running a recipe if a resource fails for any reason.
iterations
Ruby Type: Integer
macOS platform only. The number of iterations for a password with a SALTED-SHA512-PBKDF2 shadow hash.
manage_home
Ruby Type: true, false
Manage a user’s home directory.
When used with the
:create
action, a user’s home directory is created based onHOME_DIR
. If the home directory is missing, it is created unlessCREATE_HOME
in/etc/login.defs
is set tono
. When created, a skeleton set of files and subdirectories are included within the home directory.When used with the
:modify
action, a user’s home directory is moved toHOME_DIR
. If the home directory is missing, it is created unlessCREATE_HOME
in/etc/login.defs
is set tono
. The contents of the user’s home directory are moved to the new location.non_unique
Ruby Type: true, false
Create a duplicate (non-unique) user account.
notifies
Ruby Type: Symbol, ‘Chef::Resource[String]’
A resource may notify another resource to take action when its state changes. Specify a
'resource[name]'
, the:action
that resource should take, and then the:timer
for that action. A resource may notify more than one resource; use anotifies
statement for each resource to be notified.A timer specifies the point during the Chef Client run at which a notification is run. The following timers are available:
:before
- Specifies that the action on a notified resource should be run before processing the resource block in which the notification is located.
:delayed
- Default. Specifies that a notification should be queued up, and then executed at the end of the Chef Client run.
:immediate
,:immediately
- Specifies that a notification should be run immediately, per resource notified.
The syntax for
notifies
is:notifies :action, 'resource[name]', :timer
password
Ruby Type: String
The password shadow hash
retries
Ruby Type: Integer | Default Value:
0
The number of times to catch exceptions and retry the resource.
retry_delay
Ruby Type: Integer | Default Value:
2
The retry delay (in seconds).
salt
Ruby Type: String
A SALTED-SHA512-PBKDF2 hash.
shell
Ruby Type: String
The login shell.
subscribes
Ruby Type: Symbol, ‘Chef::Resource[String]’
A resource may listen to another resource, and then take action if the state of the resource being listened to changes. Specify a
'resource[name]'
, the:action
to be taken, and then the:timer
for that action.Note that
subscribes
does not apply the specified action to the resource that it listens to - for example:file '/etc/nginx/ssl/example.crt' do mode '0600' owner 'root' end service 'nginx' do subscribes :reload, 'file[/etc/nginx/ssl/example.crt]', :immediately end
In this case the
subscribes
property reloads thenginx
service whenever its certificate file, located under/etc/nginx/ssl/example.crt
, is updated.subscribes
does not make any changes to the certificate file itself, it merely listens for a change to the file, and executes the:reload
action for its resource (in this examplenginx
) when a change is detected.A timer specifies the point during the Chef Client run at which a notification is run. The following timers are available:
:before
- Specifies that the action on a notified resource should be run before processing the resource block in which the notification is located.
:delayed
- Default. Specifies that a notification should be queued up, and then executed at the end of the Chef Client run.
:immediate
,:immediately
- Specifies that a notification should be run immediately, per resource notified.
The syntax for
subscribes
is:subscribes :action, 'resource[name]', :timer
system
Ruby Type: true, false
Create a system user. This property may be used with
useradd
as the provider to create a system user which passes the-r
flag touseradd
.uid
Ruby Type: String, Integer
The numeric user identifier.
username
Ruby Type: String
The name of the user. Default value: the
name
of the resource block. See “Syntax” section above for more information.
Password Shadow Hash¶
There are a number of encryption options and tools that can be used to create a password shadow hash. In general, using a strong encryption method like SHA-512 and the passwd
command in the OpenSSL toolkit is a good approach, however the encryption options and tools that are available may be different from one distribution to another. The following examples show how the command line can be used to create a password shadow hash. When using the passwd
command in the OpenSSL tool:
openssl passwd -1 "theplaintextpassword"
When using mkpasswd
:
mkpasswd -m sha-512
For more information:
- https://www.openssl.org/docs/manmaster/man1/passwd.html
- Check the local documentation or package repository for the distribution that is being used. For example, on Ubuntu 9.10-10.04, the
mkpasswd
package is required and on Ubuntu 10.10+ thewhois
package is required.
Examples¶
The following examples demonstrate various approaches for using resources in recipes. If you want to see examples of how Chef uses resources in recipes, take a closer look at the cookbooks that Chef authors and maintains: https://github.com/chef-cookbooks.
Create a user named “random”
user 'random' do
manage_home true
comment 'User Random'
uid '1234'
gid '1234'
home '/home/random'
shell '/bin/bash'
password '$1$JJsvHslV$szsCjVEroftprNn4JHtDi'
end
Create a system user
user 'systemguy' do
comment 'system guy'
system true
shell '/bin/false'
end
Create a system user with a variable
The following example shows how to create a system user. In this instance, the home
value is calculated and stored in a variable called user_home
which sets the user’s home
attribute.
user_home = "/home/#{node['cookbook_name']['user']}"
user node['cookbook_name']['user'] do
gid node['cookbook_name']['group']
shell '/bin/bash'
home user_home
system true
action :create
end
Use SALTED-SHA512-PBKDF2 passwords
macOS 10.8 (and higher) calculates the password shadow hash using SALTED-SHA512-PBKDF2. The length of the shadow hash value is 128 bytes, the salt value is 32 bytes, and an integer specifies the number of iterations. The following code will calculate password shadow hashes for macOS 10.8 (and higher):
password = 'my_awesome_password'
salt = OpenSSL::Random.random_bytes(32)
iterations = 25000 # Any value above 20k should be fine.
shadow_hash = OpenSSL::PKCS5::pbkdf2_hmac(
password,
salt,
iterations,
128,
OpenSSL::Digest::SHA512.new
).unpack('H*').first
salt_value = salt.unpack('H*').first
Use the calculated password shadow hash with the user resource:
user 'my_awesome_user' do
password 'cbd1a....fc843' # Length: 256
salt 'bd1a....fc83' # Length: 64
iterations 25000
end