Google Internal vs Open Source
Some of Google's open source projects are born open-source, but others are siblings to the original internal projects, their names, even technical details may be different; also some famous projects are not open sourced by Google, but as an implementation of Google's published papers.
blaze is Google's internal build system, bazel is the open source version
Google published a paper about its distributed file system. HDFS, part of Hadoop, is an open source implementation of that paper.
Borg is Google's internal cluster manager, Kubernetes is modeled after Borg but works with containers, while Borg's package format is called MPM
- Borg: https://ai.google/research/pubs/pub43438
- MPM: https://www.usenix.org/conference/lisa14/conference-program/presentation/mcnutt
Google's Flume is totally different from Apache Flume. It is used for authoring data pipelines; originally on top of MapReduce, now moved to a faster underlying engine. The open source version is called Apache Beam.
Stubby is Google's internal RPC framework. gRPC is called the next generation of Stubby, and open sourced. Both depend on protobuf.