Google just tests the living Jesus out of everything, and only versions a few core packages such as protobufs, grpc, and other packages used by pretty much everybody (this is called the "crust").
Everything else is tip of tree, and things are automatically re-tested using checked-in tests if they are affected by your changelist. You basically can't submit if you break anything. So in a way, Google doesn't need "versioning". Whatever is currently checked in is good to go.
Tests are required, of course, and a Google reviewer won't let you submit anything if your tests suck. This, obviously, precludes the use of such a set-up in, shall we say, "more agile" orgs which don't have good test coverage.
Blaze (at Google) is also not just a build system, but also an interface to a much larger distributed build and test backend, which lets you rebuild everything from the kernel upwards in seconds (by caching petabytes of build products at thousands of possible revisions), serves up source code views for developer workstations (code is not stored there either), and sustains the scale of distributed testing needed for this setup to work. As a result, nobody builds or tests on their own workstation, and there's close to zero (or maybe even zero, period) binaries checked into Google3 monorepo. If you need a Haskell compiler and nobody used it in a while, it'll be rebuilt from source and cached for future use. :-)
Fundamentally, I think Google got things very, very right with Blaze. Bazel is but a pale shadow of what Blaze is, but even in its present state it is better than most (all?) other build systems.
> Blaze (at Google) is also not just a build system, but also an interface to a much larger distributed build and test backend, which lets you rebuild everything from the kernel upwards in seconds (by caching petabytes of build products at thousands of possible revisions), serves up source code views for developer workstations (code is not stored there either), and sustains the scale of distributed testing needed for this setup to work. As a result, nobody builds or tests on their own workstation, and there's close to zero (or maybe even zero, period) binaries checked into Google3 monorepo. If you need a Haskell compiler and nobody used it in a while, it'll be rebuilt from source and cached for future use. :-)
The distributed, cached builds are effectively the same thing for Brazil (at the package level), with applications, libraries, system packages, all the way down to compilers being built from source. Brazil doesn't have the level of file system abstraction that Blaze/Bazel does, and prefers towards local development using overlays version sets for certain core build tools.
>Fundamentally, I think Google got things very, very right with Blaze. Bazel is but a pale shadow of what Blaze is, but even in its present state it is better than most (all?) other build systems.
I think Bazel gets things amazingly right for a single monorepo even w/o all of the fanciness that comes from internal systems and services, but the mechanisms for managing out of source dependencies is just flat out clunky. I suspect this is because Blaze never had to really solve that problem, and I think Brazil is a much better tool for solving it because it's what it had to do.
>> mechanisms for managing out of source dependencies is just flat out clunky
I'm not sure I agree. You can reference arbitrary, versioned out of tree deps via WORKSPACE file. You can pull from git at tag or revision, you can pull from cloud storage, maven, pypi, etc. Just about any realistic scenario is supported, and those that aren't yet are easily scriptable using a restricted python-like extension language.
Everything else is tip of tree, and things are automatically re-tested using checked-in tests if they are affected by your changelist. You basically can't submit if you break anything. So in a way, Google doesn't need "versioning". Whatever is currently checked in is good to go.
Tests are required, of course, and a Google reviewer won't let you submit anything if your tests suck. This, obviously, precludes the use of such a set-up in, shall we say, "more agile" orgs which don't have good test coverage.
Blaze (at Google) is also not just a build system, but also an interface to a much larger distributed build and test backend, which lets you rebuild everything from the kernel upwards in seconds (by caching petabytes of build products at thousands of possible revisions), serves up source code views for developer workstations (code is not stored there either), and sustains the scale of distributed testing needed for this setup to work. As a result, nobody builds or tests on their own workstation, and there's close to zero (or maybe even zero, period) binaries checked into Google3 monorepo. If you need a Haskell compiler and nobody used it in a while, it'll be rebuilt from source and cached for future use. :-)
Fundamentally, I think Google got things very, very right with Blaze. Bazel is but a pale shadow of what Blaze is, but even in its present state it is better than most (all?) other build systems.