A word on cover letters: they aren’t required (and may or may not be considered), so it’s your call on whether to include one.
If you do decide to include a cover letter, many of the same suggestions we have for building a good resume apply here as well. For instance:
The following metrics were computed from 116 interview experiences for the Google Software Engineer role in Bengaluru, Karnataka.
Google's interview process for their Software Engineer roles in Bengaluru, Karnataka is extremely selective, failing the vast majority of engineers.
Candidates reported having very good feelings for Google's Software Engineer interview process in Bengaluru, Karnataka.