The Bazel Query Commands I Actually Use

Bazel has a lot of commands. Most of them you’ll never touch. Here are the ones I reach for constantly when I’m trying to figure out what’s going on in a BUILD file.

“What targets exist here?”

bazel query '//...'

Flat list. Not that useful on its own. Add --output=label_kind to see what each thing actually is:

bazel query 'kind(".*", //...)' --output=label_kind

pkg_tar_impl rule //image:app_layer
oci_image rule    //image:hello_image
oci_load rule     //image:hello_tarball
_write_file rule  //image:hello_tarball_write_tags   # internal, ignore

Now you can tell the real targets from the auto-generated ones.

“What does this target produce?”

bazel cquery --output=files //image:app_layer
# bazel-out/darwin_arm64-fastbuild/bin/image/app_layer.tar

This gives you the actual file path on disk. You can tar -tf it, cat it, whatever. This is the command I use most.

“What does this target depend on?”

bazel query 'deps(//image:app_layer, 1)'

The 1 means direct deps only. Without it you get the entire transitive tree — toolchains, Starlark files, everything. You almost never want that.

“If I change this file, what rebuilds?”

bazel query 'rdeps(//..., //app:main.py)'

This is the Bazel superpower. Reverse deps. Change main.py and Bazel tells you exactly: app_layer -> hello_image -> hello_tarball. Nothing else.

“Show me the full rule definition”

bazel query '//image:app_layer' --output=build

This expands all defaults and shows you every attribute. Super useful when you’re trying to figure out what a macro is actually generating under the hood.

pkg_tar_impl(
  name = "app_layer",
  package_dir = "/app",
  srcs = ["//app:main.py"],
  out = "//image:app_layer.tar",   # <-- there's the output
)

“What can I actually run?”

bazel query 'kind(".*_binary|.*_test|oci_load|sh_binary|py_binary", //...)'

Not everything is runnable. bazel build works on any target, but bazel run only works on targets that produce an executable.

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