isabella232 / nscd

Development repository for the nscd cookbook

nscd Cookbook

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

Requirements

Platforms

• Debian 7+
• Ubuntu 12.04+
• RHEL/CentOS 5+
• 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).

Custom 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.

License

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.

Cookbook Engineering Team

This cookbook is maintained by Chef's Cookbook Engineering team.