Failed to run task: 'bower --allow-root install --offline' failed.

제플린을 컴파일하면 제목에 기술된 문제가 발생합니다.
해결 방법:
I was getting the same problem here, and this answer is just a guide, for those who are getting the same error: The maven output was similar to yours:
[ERROR] Failed to execute goal com.github.eirslett:frontend-maven-plugin:0.0.25:bower (bower install) on project zeppelin-web: Failed to run task: 'bower --allow-root install' failed. (error code 1) -> [Help 1]
but going up a little bit it showed:
[ERROR] bower ECONFLICT Unable to find suitable version for angular
This means that bower was been executed but it couldn't choose between some available angular versions. To fix that I have gone to/zeppeling-root-folder/zeppelin-web and executed

./bower install

At the end of bower install it asked me to choose between one of the available angular versions, which I choose 1.5.0, after it just run a

npm install node-gyp@latest   

내용:http://www.itkeyword.com/doc/7017258402628137x195/failed-to-run-task-bower-allow-root-install-failed