Blueprints and Toolboxes

Duct 1.2 introduces two new configuration structures in an effort to simplify defining recurring patterns of monitoring checks. This is particularly useful when monitoring a large list of hosts from a central point.

It’s important to point out however that Duct is not well optimised for that use case since each check permutation requires a resident timer object and staggered startup can take a long time. To tune the stagger interval set the stagger global config variable to something very small, specifically acceptable_start_time/number_of_checks in seconds.

eg. If you have 1000 checks and the acceptable startup time is 5 add stagger: 0.005 to the configuration file.

Toolboxes

A toolbox defines a set of sources without any unique options. It can also define defaults to use for every source within that toolbox.

toolbox:
  linux_defaults:
    defaults:
      use_ssh: True
      interval: 10.0
    sources:
      - service: memory
        source: duct.sources.linux.basic.Memory
      - service: cpu
        source: duct.sources.linux.basic.CPU

Blueprints

A blueprint defines a set of lists to permute against specific options on a toolbox.

If for example one wanted to apply the basic set of Linux checks specified above to 3 hosts then the following configuration can be used.

blueprint:
  - toolbox: linux_defaults
    defaults:
      interval: 10.0
    sets:
      hostname:
        - www01.acme.com
        - www02.acme.com
        - www03.acme.com

The equivalent long hand version of this configuration would be as follows

sources:
    - service: memory
      source: duct.sources.linux.basic.Memory
      hostname: www01.acme.com
      use_ssh: True
      interval: 10.0

    - service: cpu
      source: duct.sources.linux.basic.CPU
      hostname: www01.acme.com
      use_ssh: True
      interval: 10.0

    - service: memory
      source: duct.sources.linux.basic.Memory
      hostname: www02.acme.com
      use_ssh: True
      interval: 10.0

    - service: cpu
      source: duct.sources.linux.basic.CPU
      hostname: www02.acme.com
      use_ssh: True
      interval: 10.0

    - service: memory
      source: duct.sources.linux.basic.Memory
      hostname: www03.acme.com
      use_ssh: True
      interval: 10.0

    - service: cpu
      source: duct.sources.linux.basic.CPU
      hostname: www03.acme.com
      use_ssh: True
      interval: 10.0

It’s easy to see that the toolbox and blueprint pattern can considerably simplify configuration.

A blueprint can also override defaults for a toolbox. Note also that a source does not validate whether or not options passed to it are recognised, this has pro’s and con’s. Namely it is possible to have an option set which would only apply to certain sources in a toolbox which recognise that option, however it might also be possible to inadvertently set options with shared names in the wrong place so always be sure to know what collisions are possible.