GroupPatterns

The GroupPatterns plugin is a connector that can assign clients group membership pased on patterns in client hostnames. Two basic methods are supported:

• regular expressions (NamePatterns)
• ranges (NameRange)

Hosts that match the specification are placed in the group or groups specified by the pattern.

Setup

1. Enable the GroupPatterns plugin
2. Create the GroupPatterns/config.xml file (similar to the example below).
3. Client groups will be augmented based on the specification

Pattern Types

NamePatterns use regular expressions to match client hostnames. All matching clients are placed in the resulting groups. NamePatterns also have the ability to use regular expression matched groups to dynamically create group names. The first two examples below are NamePatterns. The first adds client hostname to both groups gp-test1 and gp-test2. The second matches the hostname as a group and places the client in a group called group-<hostname>.

NameRange patterns allow the use of the application of numeric ranges to host names. The final pattern below matches any of node1-node32 and places them all into the rack1 group. Dynamically generated group names are not supported with NameRange.

Examples

<GroupPatterns>
  <GroupPattern>
    <NamePattern>hostname</NamePattern>
    <Group>gp-test1</Group>
    <Group>gp-test2</Group>
  </GroupPattern>
  <GroupPattern>
    <NamePattern>(.*)</NamePattern>
    <Group>group-$1</Group>
  </GroupPattern>
  <GroupPattern>
    <NameRange>node[[1-32]]</NameRange>
    <Group>rack1</Group>
  </GroupPattern>
</GroupPatterns>

Cluster Example

Functional aspects are extracted from hostname strings, and dynamic groups are created.

Expected hostname to group mapping:

xnfs1.example.com     -> nfs-server
xnfs2.example.com     -> nfs-server
xlogin1.example.com   -> login-server
xlogin2.example.com   -> login-server
xpvfs1.example.com    -> pvfs-server
xpvfs2.example.com    -> pvfs-server
xwww.example.com      -> www-server

GroupPatterns configuration:

<GroupPatterns>
  <GroupPattern>
    <NamePattern>x(\w[^\d\.]+)\d*\.</NamePattern>
    <Group>$1-server</Group>
  </GroupPattern>
</GroupPatterns>

Regex explanation:

1. x Match any hostname that begins with “x”
2. (\w[!^\d|\.]+) followed by one or more word characters that are not a decimal digit or ”.” and save the string to $1
3. \d* followed by 0 or more decimal digit(s)
4. \. followed by a literal ”.”