ntp example

Here is a series of example configurations for Bcfg2, each introducing another layer of functionality.

• After each change, run bcfg-repo-validate -v
• Run the server with bcfg2-server -v
• Update the client with bcfg2 -v -d -n (will not actually make client changes)

Package only

Our example starts with the bare minimum configuration setup. We have a client, a profile group, a list of packages, and an NTP bundle.

Metadata/clients.xml:

<Clients>
  <Client profile='server' name='foo.bar.com'/>
</Clients>

Metadata/groups.xml:

<Groups>
  <Group profile='true' name='server'>
    <Bundle name="ntp"/>
  </Group>
</Groups>

Bundler/ntp.xml:

<Bundle>
  <Package name='ntp'/>
</Bundle>

Pkgmgr/packages.xml:

<PackageList type='rpm' priority='0'>
  <Package name='ntp' version='4.2.0.a.20050816-11.FC5'/>
</PackageList>

(This can also be performed more elegantly with the Packages plugin.)

Add service

Configure the service, and add it to Rules.

Rules/services.xml:

<Services priority='0'>
  <Service name='ntpd' status='on'/>
</Services>

Bundler/ntp.xml:

<Bundle>
  <Package name='ntp'/>
  <Service name='ntpd'/>
</Bundle>

Add config file

Setup an etc/ directory structure, and add it to the base:

# cat Cfg/etc/ntp.conf/ntp.conf
server ntp1.utexas.edu

Bundler/ntp.xml:

<Bundle>
  <Package name='ntp'/>
  <Service name='ntpd'/>
   <Path name='/etc/ntp.conf'/>
</Bundle>

Create a bundle

Bundles allow the grouping of related configuration entries that are used to provide a single service. This is done for several reasons:

• Grouping related things in one place makes it easier to add those entries for multiple groups of clients
• Grouping entries into bundles makes their validation occur collectively. This means that config files can override the contents of packages. Also, config files are rechecked after packages are upgraded, so that they can be repaired if the package install clobbered them.
• Services associated with a bundle get restarted whenever any entity in that bundle is modified. This ensures that new configuration files and software are used after installation.

The config file, package, and service are really all related components describing the idea of an ntp client, so they should be logically grouped together. We use a bundle to accomplish this.

Bundler/ntp.xml:

<Bundle>
  <Package name='ntp'/>
  <Service name='ntpd'/>
  <Path name='/etc/ntp.conf'/>
</Bundle>

After this bundle is created, it must be associated with a group (or groups). Add a bundle child element to the group(s) which should install this bundle.

Metadata/groups.xml:

<Groups>
 ...
 <Group profile='true' name='server'>
   <Bundle name="ntp"/>
 </Group>
 ...
</Groups>

Once this bundle is created, a client reconfigure will install these entries. If any are modified, then the ntpd service will be restarted. If you only want ntp configurations to be updated (and nothing else), the bcfg2 client can be run with a -b <bundle name> option that will only update entries in the specified bundle.