"ERROR: 'remote' was requested for default strategies but no strategy with that identifier was registered" when using --remote_local_fallback and remote executor is down

[fwingerter-Ocient]

Description of the problem:

Even with --remote_local_fallback, builds fail when the remote executor is not reachable.

Bugs: what's the simplest, easiest way to reproduce this bug? Please provide a minimal example if possible.

$ git clone https://github.com/bazelbuild/examples/ bazel-examples
$ cd bazel-examples/cpp-tutorial/stage1
$ bazel build //... --remote_local_fallback --remote_executor=asdkfasdf:6890
Starting local Bazel server and connecting to it...
INFO: Invocation ID: fe0d20a4-cc89-4867-bce1-8cf6331fb814
WARNING: Failed to query remote execution capabilities: UNAVAILABLE: Unable to resolve host asdkfasdf
INFO: Analyzed target //main:hello-world (15 packages loaded, 57 targets configured).
INFO: Found 1 target...
ERROR: 'remote' was requested for default strategies but no strategy with that identifier was registered. Valid values are: [processwrapper-sandbox, standalone, worker, sandboxed, local]
INFO: Elapsed time: 5.410s
INFO: 0 processes.
FAILED: Build did NOT complete successfully

The WARNINGs are expected, but the ERROR is not. The ERROR can be prevented by passing --spawn_strategy=local, but this prevents using the remote executor if it is up.

What operating system are you running Bazel on?

Ubuntu 16.04.6 LTS (I know it's ancient, but I don't believe this problem is distro-related)

What's the output of bazel info release?

release 4.1.0rc1

What's the output of git remote get-url origin ; git rev-parse master ; git rev-parse HEAD ?

https://github.com/bazelbuild/examples/
b1c5b85050fa5f199f40183c84a531e458dcf8aa
b1c5b85050fa5f199f40183c84a531e458dcf8aa

Have you found anything relevant by searching the web?

It seems that this behavior is not intended according to this commit: 39512a4

[coeuvre]

39512a4 was for remote cache. The underlying problem for this error is #13340.

[fwingerter-Ocient]

The difference between this and #13340 is that I'm not explicitly setting the list of strategies at all here, and the error complains about the "default strategies" set in Bazel's implementation (as far as I can tell).

I'm happy with any changes that fix this use-case, of course. Thanks for looking into this.

[coeuvre]

Should be fixed by #13490.