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bazel: Fix bazel query and provide a default java toolchain #98611

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merged 2 commits into from Oct 19, 2020

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mfarrugi
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Motivation for this change

These are fixes for problems I ran into with:

  • bazel test //example:cpp-test
    This needed build --host_javabase='@local_jdk//:jdk'

  • bazel query 'deps(//example:cpp-test)'
    This needed the same flags as build. (Trying to get a sense of why the cpp-test needs java!)

Is it contentious to (partially?) configure the default java toolchain? I don't see it as much different than providing the bazel server's java.
It would continue to be configurable/overridable by overriding the flags.
#86410 is related.

(will rewrite commit later, web ui is tricky :))

Things done
  • Tested using sandboxing (nix.useSandbox on NixOS, or option sandbox in nix.conf on non-NixOS linux)
  • Built on platform(s)
    • NixOS
    • macOS
    • other Linux distributions
  • Tested via one or more NixOS test(s) if existing and applicable for the change (look inside nixos/tests)
  • Tested compilation of all pkgs that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review wip"
  • Tested execution of all binary files (usually in ./result/bin/)
  • Determined the impact on package closure size (by running nix path-info -S before and after)
  • Ensured that relevant documentation is up to date
  • Fits CONTRIBUTING.md.

And a random notes from this escapade, but https://github.com/bazelbuild/bazel/blob/master/WORKSPACE#L144-L308 looks a little different from https://github.com/NixOS/nixpkgs/blob/master/pkgs/development/tools/build-managers/bazel/bazel_3/src-deps.json so one of them is probably wrong :)

These are fixes for problems I ran into with:
- `bazel test //example:cpp-test`
This needed `build --host_javabase='@local_jdk//:jdk'`

- `bazel query 'deps(//example:cpp-test)'`
This needed the same flags as `build`.

Is it contentious to (partially?) configure the default java toolchain? I don't see it as much different than providing the bazel server's java.
It would continue to be configurable/overridable by overriding the flags. 

---
And a random notes from this escapade, but https://github.com/bazelbuild/bazel/blob/master/WORKSPACE#L144-L308 looks a little different from https://github.com/NixOS/nixpkgs/blob/master/pkgs/development/tools/build-managers/bazel/bazel_3/src-deps.json so one of them is probably wrong :)
@infinisil
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Could this be related to tweag/rules_haskell#1414? In my quick testing, this PR's bazel didn't fix that issue, so maybe not.

@mfarrugi
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mfarrugi commented Sep 28, 2020 via email

@Profpatsch
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@aherrmann does this look familiar to you?

@aherrmann
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The problem with bazel query is that it doesn't take configuration into account. Meaning it won't evaluate selects or apply platform constraints to select a toolchain. The cquery command is an alternative that does take configuration into account. In the rules_haskell/tutorial example it seems to work without error (cc @infinisil)

$ nix-shell --pure ../shell.nix --run 'bazel cquery --nohost_deps --noimplicit_deps "deps(//main:demorgan)"'
...
//main:demorgan (e05802078203a74d9644c5b7ab2f441c7edc77c7cf9c943d34e190a170d74972)
//lib:booleans (e05802078203a74d9644c5b7ab2f441c7edc77c7cf9c943d34e190a170d74972)
//main:Main.hs (null)
//main:base (e05802078203a74d9644c5b7ab2f441c7edc77c7cf9c943d34e190a170d74972)
//lib:Bool.hs (null)
...

@Profpatsch
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So sounds to me like this is a “works as intended” situation? It is confusing, but we can’t really compensate for it.

@mfarrugi
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If you use bazel with internet access, it will download the other platforms' java_tools to resolve the query. Given that nix is doing the fetching, I think this makes sense. The cost to this fix is downloading two extra .zip files that total ~100mb.

I can see the argument that a person shouldn't be using bazel query over bazel cquery, but I see no plans to remove the former and as long as it's there it should work out of the box.

Separately, any thoughts on the --host_javabase change? This seems strictly better for users.

@Profpatsch
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I am not deep enough into the bazel build anymore to have much of an opinion on whether this change is correct, it is all very confusing and you never know if things have to be there because of a bug in bazel or a works-as-intended.

So I’d say let’s merge this and see what breaks.

@Profpatsch
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And a random notes from this escapade, but https://github.com/bazelbuild/bazel/blob/master/WORKSPACE#L144-L308 looks a little different from https://github.com/NixOS/nixpkgs/blob/master/pkgs/development/tools/build-managers/bazel/bazel_3/src-deps.json so one of them is probably wrong :)

I nearly missed this, but I don’t understand what you mean by that? Can you elaborate?

@mfarrugi
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mfarrugi commented Oct 13, 2020 via email

@Profpatsch
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Profpatsch commented Oct 13, 2020 via email

@mfarrugi
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mfarrugi commented Oct 13, 2020 via email

@Profpatsch
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is parsing the entire WORKSPACE file, so it is indeed a superset. It could probably just read additional_distfiles from bazel, but I'm not interested in pursuing this further.

I’m sorry, I still don’t understand what you mean. What exactly is the problem here?

@mfarrugi
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It's not relevant to this PR.

https://docs.bazel.build/versions/master/guide.html#running-bazel-in-an-airgapped-environment suggests that bazel should only need https://github.com/bazelbuild/bazel/blob/master/WORKSPACE#L144-L308 to work airgapped.  We are doing something different than bazel build @additional_distfiles//:archives.tar that, if the docs are to be believed, are downloading a superset of the necessary files.

@Profpatsch
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Profpatsch commented Oct 19, 2020 via email

@Profpatsch Profpatsch merged commit ffac55a into NixOS:master Oct 19, 2020
@Profpatsch
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Okay, I merged under the assumption that this PR does set a sensible default. We’ll see if any complaints come in.

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5 participants