altsrc

New in version 0.9.5.

Altsrc is a generic, Bcfg2 server-side mechanism for performing configuration entry name remapping for the purpose of data binding. Altsrc can be used as a parameter for any entry type, and can be used in any structure.

Use Cases

  • Equivalent configuration entries on different architectures with different names
  • Mapping entries with the same name to different bind results in a configuration (two packages with the same name but different types)
  • A single configuration entry across multiple specifications (multi-plugin, or multi-repo)

Examples

  • Consider the case of /etc/hosts on linux and /etc/inet/hosts on solaris. These files contain the same data in the same format, and should typically be synchronized, however, exist in different locations. Classically, one would need to create one entry for each in Cfg and perform manual synchronization. Or, you could use symlinks and pray. Altsrc is driven from the bundle side. For example:

    <Bundle>
   <Group name='solaris'>
     <Path name='/etc/inet/hosts' altsrc='/etc/hosts'/>
   </Group>
   <Group name='linux'>
     <Path name='/etc/hosts'/>
   </Group>
</Bundle>

    In this case, when a solaris host gets the ‘netinfo’ bundle, it will get the first Path entry, which includes an altsrc parameter. This will cause the server to bind the entry as if it were a Path called /etc/hosts. This configuration entry is still called /etc/inet/hosts, and is installed as such.

  • On encap systems, frequently multiple packages of the same name, but of different types will exist. For example, there might be an openssl encap package, and an openssl rpm package. This can be dealt with using a bundle like:

    <Bundle>
   <Package name='openssl' altsrc='openssl-encap'/>
   <Package name='openssl' altsrc='openssl-rpm'/>
</Bundle>

    This bundle will bind data for the packages “openssl-encap” and “openssl-rpm”, but will be delivered to the client with both packages named “openssl” with different types.

  • Consider the case where there exist complicated, but completely independent specifications for the same configuration entry but different groups of clients. The following bundle will allow the use of two different templates /etc/firewall-rules-external and /etc/firewall-rules-internal for different clients based on their group membership.

    <Bundle>
   ...
   <Group name='conduit'>
     <Path name='/etc/firewall-rules' altsrc='/etc/firewall-rules-external'/>
   </Group>
   <Group name='internal'>
     <Path name='/etc/firewall-rules' altsrc='/etc/firewall-rules-internal'/>
   </Group>
</Bundle>

  • Consider the case where a variety of files can be constructed by a single Genshi or Cheetah template. It would be possible to copy this template into the proper location for each file, but that requires proper synchronization upon modification and knowing up front what the files will all be called. Instead, the following bundle allows the use of a single template for all proper config file instances.

    <Bundle>
  <Path name='/etc/sysconfig/network-scripts/ifcfg-eth0' altsrc='/etc/ifcfg-template'/>
  <Path name='/etc/sysconfig/network-scripts/ifcfg-eth1' altsrc='/etc/ifcfg-template'/>
  <Path name='/etc/sysconfig/network-scripts/ifcfg-eth2' altsrc='/etc/ifcfg-template'/>
</Bundle>