nscd Cookbook

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Installs and configures name service cache daemon (nscd). Provides a custom resource for clearing nscd database caches.

Maintainers

This cookbook is maintained by the Sous Chefs. The Sous Chefs are a community of Chef cookbook maintainers working together to maintain important cookbooks. If you’d like to know more please visit sous-chefs.org (opens in a new tab) or come chat with us on the Chef Community Slack in #sous-chefs (opens in a new tab).

Requirements

Platforms

Debian 9+
Ubuntu 18.04+
RHEL/CentOS 7+
openSUSE
Fedora
SmartOS

Chef

Chef 12.5+

Cookbooks

none

Attributes

default['nscd']['template_cookbook'] - nscd cookbook name. You can override this attribute if you want to pass in a custom template for nscd.conf
default['nscd']['package'] - nscd package name, defaults to nscd. Other variants include: unscd, gnscd
default['nscd']['version'] - nscd version, defaults to nil. If set to nil, the latest will be installed.

The following attributes affect configuration of /etc/nscd.conf.

default['nscd']['logfile']. Specifies name of the file to which debug info should be written. Default /var/log/nscd
default['nscd']['threads']. This is the number of threads that are started to wait for requests. At least five threads will always be created. Default 4
default['nscd']['max_threads']. Specifies the maximum number of threads. Default 32
default['nscd']['server_user']. If this option is set, nscd will run as this user and not as root. If a separate cache for every user is used (-S parameter), this option is ignored. Default nscd
default['nscd']['stat_user']. Specifies the user who is allowed to request statistics. Default root
default['nscd']['debug_level']. Sets the desired debug level. Default 0
default['nscd']['reload_count']. Limit on the number of times a cached entry gets reloaded without being used before it gets removed. Default 5
default['nscd']['paranoia']. Enabling paranoia mode causes nscd to restart itself periodically. Default no
default['nscd']['restart_interval']. Sets the restart interval to time seconds if periodic restart is enabled by enabling paranoia mode. Default 3600
default['nscd']['databases']. List of databases to configure. Default %[passwd group hosts services netgroup]

Each database has attributes, default depends on SERVICE, see attribute file.

default['nscd'][SERVICE]['enable_cache']. Enables or disables the specified SERVICE cache.
default['nscd'][SERVICE]['positive_time_to_live']. Sets the TTL (time-to-live) for positive entries (successful queries) in the specified cache for service. Value is in seconds. Larger values increase cache hit rates and reduce mean response times, but increase problems with cache coherence.
default['nscd'][SERVICE]['negative_time_to_live']. Sets the TTL (time-to-live) for negative entries (unsuccessful queries) in the specified cache for service. Value is in seconds. Can result in significant performance improvements if there are several files owned by UIDs (user IDs) not in system databases (for example untarring the Linux kernel sources as root); should be kept small to reduce cache coherency problems.
default['nscd'][SERVICE]['suggested_size']. This is the internal hash table size, value should remain a prime number for optimum efficiency.
default['nscd'][SERVICE]['check_files']. Enables or disables checking the file belonging to the specified service for changes. The files are /etc/passwd, /etc/group, /etc/hosts, /etc/services and /etc/netgroup.
default['nscd'][SERVICE]['persistent']. Keep the content of the cache for service over server restarts; useful when paranoia mode is set.
default['nscd'][SERVICE]['shared']. The memory mapping of the nscd databases for service is shared with the clients so that they can directly search in them instead of having to ask the daemon over the socket each time a lookup is performed.
default['nscd'][SERVICE]['max_db_size']. The maximum allowable size, in bytes, of the database files for the service.
default['nscd'][SERVICE]['auto_propagate']. When set to no for passwd or group service, then the .byname requests are not added to passwd.byuid or group.bygid cache. This can help with tables containing multiple records for the same ID. This option is valid only for services passwd and group.

Recipes

default

Installs nscd, manages the nscd service and makes available commands to clear the nscd databases (passwd and group) so they can be notified in other recipes (such as when managing openldap).

Resources

clear_cache The clear_cache custom resource provides a simple way to clear the cache of 1 or more nscd databases from other recipes.

Actions

:clear: clears the nscd database cache

Properties

databases: Array of nscd databases (defaults to passwd group hosts services, and netgroup)

Examples

Clearing caches of passwd, and group databases

nscd_clear_cache 'clear-nscd-caches' do
  databases %w(passwd group)
end

Clearing caches of passwd, and group databases via notification so the databases are only cleared when another change is made.

nscd_clear_cache 'clear-nscd-caches' do
  databases %w(passwd group)
  action :nothing
end
 
template '/etc/nsswitch.conf' do
  notifies :clear, 'nscd_clear_cache[clear-nscd-caches]', :immediately
end

Usage

If you're using nscd, add this recipe. If you need to clear database cache within other recipes using the nscd_clear_cache custom resource.

Note: Version 2.0 of this cookbook replaces notifying execute resource for clearing caches with the nscd_clear_cache custom resource.

Contributors

This project exists thanks to all the people who contribute. (opens in a new tab)

Backers

Thank you to all our backers!