So far, Rally assumes that Elasticsearch is built with Gradle. It also enforces this requirement for any plugins that are built from sources. With the recent switch of Elasticsearch to the Gradle Wrapper, Gradle is not a hard requirement for Rally anymore.

Instead of hardcoding Gradle as a build tool, we should simply be agnostic and let the user define the appropriate build command(s) in the config file. Note that we will make no effort to dynamically detect anything or allow version-specific build commands (e.g. Maven for ES 2.x, Gradle for 5.x and Gradle Wrapper for 6.x). It is up to the user to configure the correct build command(s) but Rally's default configuration will be maintained to be able to build recent master versions of Elasticsearch.

Tasks:

• Remove build tool detection in initial configuration
• Remove build tool requirement from docs
• Change plugin docs to mention that the full command needs to be specified
• Migrate existing configurations to include the Gradle Wrapper for the Elasticsearch build
• Adapt Rally's source build component to use the new properties