In Drone, each pipeline is a separate Yaml document, and you cannot use anchors across Yaml documents per the Yaml specification. So unfortunately this would not be an option for you. With that being said, Drone does have support for Jsonnet, which is a configuration language from Google that can be used to generate Yaml files and has some great features that allow de-duping. See Jsonnet | Drone
See also: http://discuss.harness.io/t/how-to-reduce-yaml-boilerplate/3704