Ansible Dot-diff Library

Nested structure diff library with dot-path notation for Ansible.

Description

This package is built to plug into Ansible's module_utils, which doesn't require it to be installed on managed remote hosts, only the controller. It will be picked up by Ansiballz, which zips a module's dependencies and ships it over SSH. The library is kept small to keep the footprint down.

Usage

By design, the algorithm will ignore any keys that are omitted on the right (the target), to allow an API endpoint to choose plausible defaults. For example, an API client implementing this library will diff the desired state with a JSON REST resource to predict whether or not a REST call needs to occur for the user's changes to be applied.

from ansible.module_utils.dotdiff import dotdiff

orig = { 'one': 'one',

'two': 'two' }

dest = { 'one': 'another',

'three': 'three' }

dotdiff(orig, dest)

dotdiff() yields a list of DiffEntry objects:

[one: "one" => "another", three: "<undefined>" => "three"]

Keys that would be added to the structure in this transaction have their values marked as '<undefined>'.

Nested lists and dictionaries are supported at an arbitrary level and will be indicated using dot-separated paths. Changing a list's member count will yield a DiffEntry indicating a change in cardinality with a pound (#) sign.

mylist.#: "3" => "4"

This visualization is inspired by Terraform.

License

MIT.