How to use
- Copy the installation command and review the source package before installing it in your own agent environment.
- Check the source document for required tools, credentials and supported hosts.
- Describe your input and desired deliverable; review the output against the source material.
npx skills add https://github.com/mohitmishra786/low-level-dev-skills --skill bazelBefore you start
- Installation does not include a model subscription, API allowance or permission to access your files.
- Repository stars and installation counts describe activity, not an independent quality or security test.
Original skill document
Rendered from the source repository. Headings, examples, code, tables, links, and referenced images are preserved.
Bazel
Purpose
Guide agents through Bazel for C/C++ projects: writing BUILD files, cclibrary/ccbinary rules, toolchain registration, remote execution, dependency graph queries, Bzlmod dependency management, and sandbox debugging.
Triggers
- "How do I write a Bazel BUILD file for a C++ library?"
- "How do I add external dependencies with Bzlmod?"
- "How do I debug Bazel sandbox errors?"
- "How do I query the Bazel dependency graph?"
- "How do I set up remote execution with Bazel?"
- "How do I register a custom C++ toolchain?"
Workflow
1. Workspace structure
my-project/
├── MODULE.bazel # Bzlmod dependency file (Bazel ≥6)
├── WORKSPACE # legacy (still needed for some features)
├── BUILD # root build file
├── src/
│ ├── BUILD
│ └── main.cc
└── lib/
├── BUILD
├── mylib.cc
└── mylib.h2. Basic BUILD file — cclibrary / ccbinary
python
# lib/BUILD
cc_library(
name = "mylib",
srcs = ["mylib.cc"],
hdrs = ["mylib.h"],
copts = ["-Wall", "-Wextra", "-std=c++17"],
visibility = ["//visibility:public"],
deps = [
"@com_google_absl//absl/strings", # external dep
"//util:helpers", # internal dep
],
)
cc_test(
name = "mylib_test",
srcs = ["mylib_test.cc"],
deps = [
":mylib",
"@com_google_googletest//:gtest_main",
],
)python
# src/BUILD
cc_binary(
name = "main",
srcs = ["main.cc"],
deps = ["//lib:mylib"],
linkopts = ["-lpthread"],
)bash
# Build
bazel build //src:main
bazel build //... # build everything
# Test
bazel test //lib:mylib_test
bazel test //... # run all tests
# Run
bazel run //src:main -- arg1 arg2
# Output path
bazel-bin/src/main3. Bzlmod — modern dependency management
python
# MODULE.bazel
module(
name = "my_project",
version = "1.0",
)
bazel_dep(name = "abseil-cpp", version = "20240116.2")
bazel_dep(name = "googletest", version = "1.14.0")
bazel_dep(name = "rules_cc", version = "0.0.9")
bazel_dep(name = "platforms", version = "0.0.8")
# For http_archive deps not yet in BCR (Bazel Central Registry)
# Use module extensionsbash
# Check available versions
bazel mod graph | head -30
# Show dependency tree
bazel mod deps --depth=24. Dependency graph queries
bash
# Show all dependencies of a target
bazel query "deps(//src:main)"
# Find reverse dependencies (who depends on this?)
bazel query "rdeps(//..., //lib:mylib)"
# Find what changed between builds
bazel query "filter('//lib', deps(//src:main))"
# cquery — configuration-aware query
bazel cquery "deps(//src:main)" --output=files
# Show include paths for a target
bazel cquery "//lib:mylib" --output=build
# Find cycles in the build graph
bazel query --nohost_deps --noimplicit_deps \
"somepath(//src:main, //lib:mylib)"
# aquery — action graph (shows compiler flags, inputs, outputs)
bazel aquery "//src:main"
bazel aquery "//src:main" --output=jsonproto | jq '.actions[0].arguments'5. Toolchain registration
python
# platforms/BUILD
platform(
name = "linux_x86_64",
constraint_values = [
"@platforms//os:linux",
"@platforms//cpu:x86_64",
],
)
# toolchains/BUILD
cc_toolchain_suite(
name = "my_toolchain",
toolchains = {
"k8": ":my_k8_toolchain",
},
)
cc_toolchain(
name = "my_k8_toolchain",
all_files = ":empty",
compiler_files = ":compiler_wrapper",
# ... other file groups
)
toolchain(
name = "my_cc_toolchain",
toolchain = ":my_k8_toolchain",
toolchain_type = "@bazel_tools//tools/cpp:toolchain_type",
target_compatible_with = ["@platforms//os:linux"],
)python
# MODULE.bazel — register toolchain
register_toolchains("//toolchains:my_cc_toolchain")6. Remote execution
bash
# Use --remote_executor flag
bazel build //... \
--remote_executor=grpc://buildgrid.example.com:50051 \
--remote_instance_name=main
# Google Cloud Build Remote Execution
bazel build //... \
--remote_executor=remotebuildexecution.googleapis.com \
--remote_instance_name=projects/my-project/instances/default \
--google_default_credentials
# Caching (without remote execution)
bazel build //... \
--remote_cache=grpc://cache.example.com:9092
# Show what's cached
bazel build //... --remote_upload_local_results=true7. Sandbox debugging
bash
# Show sandbox inputs and outputs
bazel build //src:main --sandbox_debug
# Run build with verbose sandboxing
bazel build //src:main --verbose_failures --sandbox_debug
# Disable sandbox entirely (for debugging)
bazel build //src:main --spawn_strategy=local
# Common sandbox errors
# "No such file or directory" → missing data dependency
# Fix: add file to `data = [...]` attribute
# "Permission denied" → trying to write outside sandbox
# Fix: use genrule output paths instead of hardcoded paths
# "FAILED: Build did NOT complete successfully" → check verbose output
# See the exact command Bazel ran
bazel build //src:main --subcommandsFor Bazel C++ toolchain configuration, see references/bazel-cpp-toolchain.md.
Related skills
- Use
skills/build-systems/cmakefor CMake as an alternative build system - Use
skills/build-systems/build-accelerationfor sccache integration with Bazel remote cache - Use
skills/compilers/gccorskills/compilers/clangfor compiler flags used in Bazelcopts
