SECO Range

SECO range is a cluster-based metadata store developed and maintained by Yahoo!

The Range project is hosted here:

https://github.com/ytoolshed/range

Learn more about range here:

https://github.com/ytoolshed/range/wiki/

Prerequisites

To utilize range support in Salt, a range server is required. Setting up a range server is outside the scope of this document. Apache modules are included in the range distribution.

With a working range server, cluster files must be defined. These files are written in YAML and define hosts contained inside a cluster. Full documentation on writing YAML range files is here:

https://github.com/ytoolshed/range/wiki/%22yamlfile%22-module-file-spec

Additionally, the Python seco range libraries must be installed on the salt master. One can verify that they have been installed correctly via the following command:

python -c 'import seco.range'

If no errors are returned, range is installed successfully on the salt master.

Preparing Salt

Range support must be enabled on the salt master by setting the hostname and port of the range server inside the master configuration file:

range_server: my.range.server.com:80

Following this, the master must be restarted for the change to have an effect.

Targeting with Range

Once a cluster has been defined, it can be targeted with a salt command by using the -R or --range flags.

For example, given the following range YAML file being served from a range server:

$ cat /etc/range/test.yaml
CLUSTER: host1..100.test.com
APPS:
  - frontend
  - backend
  - mysql

One might target host1 through host100 in the test.com domain with Salt as follows:

salt --range %test:CLUSTER test.version

The following salt command would target three hosts: frontend, backend, and mysql:

salt --range %test:APPS test.version