There is a moderate working plugin for IDEA to support Yaml / Ansible.
Yaml-parser in the current version rather basic and only works for a very simple Yaml. The branch "snakeyaml" has begun work on integration SnakeYAML as the parser - with varying success. It can be used as a starting point.
* running the current version of the plugin successfully recognizing and structuring all the entities described in the current version Yaml specification. Should parse all the examples in the documentation and tests of Yaml/SnakeYaml. Bugs 4, 10, 13, 19
* work in version Ultimate (№14 bug and probably 22)
* correctly collapsing arrays and dictionaries (21)
Later (does not refer to this job) will be continued about Jinja2 tags to be treated as a separate injected language.