Starting with Bazel v0.19, if you have Starlark (formerly known as "Skylark") code that references #bazel_tools//tools/jdk:jar, you see messages like this at build time:
WARNING: <trimmed-path>/external/bazel_tools/tools/jdk/BUILD:79:1: in alias rule #bazel_tools//tools/jdk:jar: target '#bazel_tools//tools/jdk:jar' depends on deprecated target '#local_jdk//:jar': Don't depend on targets in the JDK workspace; use #bazel_tools//tools/jdk:current_java_runtime instead (see https://github.com/bazelbuild/bazel/issues/5594)
I think I could make things work with #bazel_tools//tools/jdk:current_java_runtime if I wanted access to the java command, but I'm not sure what I'd need to do to get the jar tool to work. The contents of the linked GitHub issue didn't seem to address this particular problem.
I stumbled across a commit to Bazel that makes a similar adjustment to the Starlark java rules. It uses the following pattern: (I've edited the code somewhat)
# in the rule attrs:
"_jdk": attr.label(
default = Label("//tools/jdk:current_java_runtime"),
providers = [java_common.JavaRuntimeInfo],
),
# then in the rule implementation:
java_runtime = ctx.attr._jdk[java_common.JavaRuntimeInfo]
jar_path = "%s/bin/jar" % java_runtime.java_home
ctx.action(
inputs = ctx.files._jdk + other inputs,
outputs = [deploy_jar],
command = "%s cmf %s" % (jar_path, input_files),
)
Additionally, java is available at str(java_runtime.java_executable_exec_path) and javac at "%s/bin/javac" % java_runtime.java_home.
See also, a pull request with a simpler example.
Because my reference to the jar tool is inside a genrule within top-level macro, rather than a rule, I was unable to use the approach from Rodrigo's answer. I instead explicitly referenced the current_java_runtime toolchain and was then able to use the JAVABASE make variable as the base path for the jar tool.
native.genrule(
name = genjar_rule,
srcs = [<rules that create files being jar'd>],
cmd = "some_script.sh $(JAVABASE)/bin/jar $# $(SRCS)",
tools = ["some_script.sh", "#bazel_tools//tools/jdk:current_java_runtime"],
toolchains = ["#bazel_tools//tools/jdk:current_java_runtime"],
outs = [<some outputs>]
)
Related
I have a code analysis tool that I'd like to run for each cc_library (and cc_binary, silently implied for rest of the question). The tool has a CLI interfaces taking:
A tool project file
Compiler specifics, such as type sizes, built-ins, macros etc.
Files to analyze
File path, includes, defines
Rules to (not) apply
Files to add to the project
Options for synchronizing files with build data
JSON compilation database
Parse build log
Analyze and generate analysis report
I've been looking at how to integrate this in Bazel so that the files to analyze AND the associated includes and defines are updated automatically, and that any analysis result is properly cached. Generating JSON compilation database (using third party lib) or parsing build log both requires separate runs and updating the source tree. For this question I consider that a workaround I'm trying to remove.
What I've tried so far is using aspects, adding an analysis aspect to any library. The general idea is having a base project file holding library invariant configuration, appended with the cc_library files to analysis, and finally an analysis is triggered generating the report. But I'm having trouble to execute, and I'm not sure it's even possible.
This is my aspect implementation so far, trying to iterate through cc_library attributes and target compilation context:
def _print_aspect_impl(target, ctx):
# Make sure the rule has a srcs attribute
if hasattr(ctx.rule.attr, 'srcs'):
# Iterate through the files
for src in ctx.rule.attr.srcs:
for f in src.files.to_list():
if f.path.endswith(".c"):
print("file: ")
print(f.path)
print("includes: ")
print(target[CcInfo].compilation_context.includes)
print("quote_includes: ")
print(target[CcInfo].compilation_context.quote_includes)
print("system_includes: ")
print(target[CcInfo].compilation_context.system_includes)
print("define: " + define)
print(ctx.rule.attr.defines)
print("local_defines: ")
print(ctx.rule.attr.local_defines)
print("") # empty line to separate file prints
return []
What I cannot figure out is how to get ALL includes and defines used when compiling the library:
From libraries depended upon, recursively
copts, defines, includes
From the toolchain
features, cxx_builtin_include_directories
Questions:
How do I get the missing flags, continuing on presented technique?
Can I somehow retrieve the compile action command string?
Appended to analysis project using the build log API
Some other solution entirely?
Perhaps there is something one can do with cc_toolchain instead of aspects...
Aspects are the right tool to do that. The information you're looking for is contained in the providers, fragments, and toolchains of the cc_* rules the aspect has access to. Specifically, CcInfo has the target-specific pieces, the cpp fragment has the pieces configured from the command-line flag, and CcToolchainInfo has the parts from the toolchain.
CcInfo in target tells you if the current target has that provider, and target[CcInfo] accesses it.
The rules_cc my_c_compile example is where I usually look for pulling out a complete compiler command based on a CcInfo. Something like this should work from the aspect:
load("#rules_cc//cc:action_names.bzl", "C_COMPILE_ACTION_NAME")
load("#rules_cc//cc:toolchain_utils.bzl", "find_cpp_toolchain")
[in the impl]:
cc_toolchain = find_cpp_toolchain(ctx)
feature_configuration = cc_common.configure_features(
ctx = ctx,
cc_toolchain = cc_toolchain,
requested_features = ctx.features,
unsupported_features = ctx.disabled_features,
)
c_compiler_path = cc_common.get_tool_for_action(
feature_configuration = feature_configuration,
action_name = C_COMPILE_ACTION_NAME,
)
[in the loop]
c_compile_variables = cc_common.create_compile_variables(
feature_configuration = feature_configuration,
cc_toolchain = cc_toolchain,
user_compile_flags = ctx.fragments.cpp.copts + ctx.fragments.cpp.conlyopts,
source_file = src.path,
)
command_line = cc_common.get_memory_inefficient_command_line(
feature_configuration = feature_configuration,
action_name = C_COMPILE_ACTION_NAME,
variables = c_compile_variables,
)
env = cc_common.get_environment_variables(
feature_configuration = feature_configuration,
action_name = C_COMPILE_ACTION_NAME,
variables = c_compile_variables,
)
That example only handles C files (not C++), you'll have to change the action names and which parts of the fragment it uses appropriately.
You have to add toolchains = ["#bazel_tools//tools/cpp:toolchain_type"] and fragments = ["cpp"] to the aspect invocation to use those. Also see the note in find_cc_toolchain.bzl about the _cc_toolchain attr if you're using legacy toolchain resolution.
The information coming from the rules and the toolchain is already structured. Depending on what your analysis tool wants, it might make more sense to extract it directly instead of generating a full command line. Most of the provider, fragment, and toolchain is well-documented if you want to look at those directly.
You might pass required_providers = [CcInfo] to aspect to limit propagation to rules which include it, depending on how you want to manage propagation of your aspect.
The Integrating with C++ Rules documentation page also has some more info.
What is the best way to refer to an external package's path in any arbitrary files processed by Bazel?
I'm trying to understand how Bazel preprocesses BUILD and .bzl files. I see instances where strings contain calls to package() and I am wondering how it works (and could not find any relevant documentation). Here is an example of this:
I have a toolchain which BUILD file contains the following expression :
cc_toolchain_config(
name = "cc-toolchain-config",
abi_libc_version = "glibc_" + host_gcc8_bundle()["pkg_version"]["glibc"],
abi_version = "gcc-" + host_gcc8_bundle()["version"],
compiler = "gcc-" + host_gcc8_bundle()["version"],
cpu = "x86_64",
cxx_builtin_include_directories = [
"%package(#host_gcc8_toolchain//include/c++/8)%",
"%package(#host_gcc8_toolchain//lib64/gcc/x86_64-unknown-linux-gnu/8/include-fixed)%",
"%package(#host_gcc8_kernel_headers//include)%",
"%package(#host_gcc8_glibc//include)%",
],
host_system_name = "x86_64-unknown-linux-gnu",
target_libc = "glibc_" + host_gcc8_bundle()["pkg_version"]["glibc"],
target_system_name = "x86_64-unknown-linux-gnu",
toolchain_identifier = "host_linux_gcc8",
)
From my understanding, the cxx_builtin_include_directories defines a list of strings to serve as the --sysroot option passed to GCC as detailed in https://docs.bazel.build/versions/0.23.0/skylark/lib/cc_common.html These strings are in the format %sysroot%.
Since package(#host_gcc8_toolchain//include/c++/8) for example, does not mean anything to GCC, bazel has to somehow expand this function to produce the actual path to the files included in the package before passing them to the compiler driver.
But how can it determine that this needs to be expanded and that it is not a regular string ? So how does Bazel preprocess the BUILD file ? Is it because of the % ... % pattern ? Where is this documented ?
is "%package(#external_package//target)%" a pattern that can be used elsewhere ? In any BUILD file ? Where do I find Bazel documentation showing how this works ?
These directives are expanded by cc_common.create_cc_toolchain_config_info within the cc_toolchain_config rule implementation not any sort of preprocessing on the BUILD file (I.e., "%package(#host_gcc8_glibc//include)%" is literally passed into the cc_toolchain_config rule.) I'm not aware that these special expansions are completely documented anywhere but the source.
Bazel has been working great for me recently, but I've stumbled upon a question for which I have yet to find a satisfactory answer:
How can one collect all files bearing a certain extension from the workspace?
Another way of phrasing the question: how could one obtain the functional equivalent of doing a glob() across a complete Bazel workspace?
Background
The goal in this particular case is to collect all markdown files to run some checks and generate a static site from them.
At first glance, glob() sounds like a good idea, but will stop as soon as it runs into a BUILD file.
Current Approaches
The current approach is to run the collection/generation logic outside of the sandbox, but this is a bit dirty, and I'm wondering if there is a way that is both "proper" and easy (ie, not requiring that each BUILD file explicitly exposes its markdown files.
Is there any way to specify, in the workspace, some default rules that will be added to all BUILD files?
You could write an aspect for this to aggregate markdown files in a bottom-up manner and create actions on those files. There is an example of a file_collector aspect here. I modified the aspect's extensions for your use case. This aspect aggregates all .md and .markdown files across targets on the deps attribute edges.
FileCollector = provider(
fields = {"files": "collected files"},
)
def _file_collector_aspect_impl(target, ctx):
# This function is executed for each dependency the aspect visits.
# Collect files from the srcs
direct = [
f
for f in ctx.rule.files.srcs
if ctx.attr.extension == f.extension
]
# Combine direct files with the files from the dependencies.
files = depset(
direct = direct,
transitive = [dep[FileCollector].files for dep in ctx.rule.attr.deps],
)
return [FileCollector(files = files)]
markdown_file_collector_aspect = aspect(
implementation = _file_collector_aspect_impl,
attr_aspects = ["deps"],
attrs = {
"extension": attr.string(values = ["md", "markdown"]),
},
)
Another way is to do a query on file targets (input and output files known to the Bazel action graph), and process these files separately. Here's an example querying for .bzl files in the rules_jvm_external repo:
$ bazel query //...:* | grep -e ".bzl$"
//migration:maven_jar_migrator_deps.bzl
//third_party/bazel_json/lib:json_parser.bzl
//settings:stamp_manifest.bzl
//private/rules:jvm_import.bzl
//private/rules:jetifier_maven_map.bzl
//private/rules:jetifier.bzl
//:specs.bzl
//:private/versions.bzl
//:private/proxy.bzl
//:private/dependency_tree_parser.bzl
//:private/coursier_utilities.bzl
//:coursier.bzl
//:defs.bzl
I've got a Java project I'm converting to Bazel.
As is typical with Java projects, there are property files with placeholders that need to be resolved/substituted at build time.
Some of the values can be hardcoded in a BUILD or BZL file:
BUILD_PROPERTIES = { "pom.version": "1.0.0", "pom.group.id": "com.mygroup"}
Some of the variables are "stamps" (e.g. BUILD_TIMESTAMP, GIT_REVISION, etc): The source for these variables are volatile-status.txt and stable-status.txt
I must generate a POM for publish, so I use #bazel_common//tools/maven:pom_file in BUILD
(assume that I need ALL the values described above for my pom template):
_local_build_properties = {}
_local_build_properties.update(BUILD_PROPERTIES)
# somehow add workspace status properties?
# add / override
_local_build_properties.update({
"pom.project.name": "my-submodule",
"pom.project.description": "My submodule description",
"pom.artifact.id": "my-submodule",
})
# Variable placeholders in the pom template are wrapped with {}
_pom_substitutions = { '{'+k+'}':v for (k,v) in _local_build_properties.items()}
pom_file(
name = "my_submodule_pom",
targets = [
"//my-submodule",
],
template_file = "//:pom_template.xml",
substitutions = _pom_substitutions,
)
So, my questions are:
How do I get key-value pairs from volatile/stable -status.txt into the
dictionary I need for pom_file.substitutions?
pom_file depends on java_library so that it can write its dependencies
into the POM. How do I update the jar generated by java_library with the
pom?
Once I have the pom and the updated jar containing the pom, how do I publish to a Maven repo?
When I look at existing code, for example rules_docker, it seems that the implementation always bails to a local executable (shell | python | go) to do the real work of substitution, jar manipulation and image publication. Am I trying to do too much in BUILD and BZL files? Should I be thinking, "Ultimately, what do I need to pass to local shell/python/go scripts to get real build work done?
(Answered on bazel-discuss group)
Hi,
You can't get these values from Starlark. You need a genrule to read the stable/volatile files and do the substitutions using an
external tool like 'sed'.
A file cannot be both an input and output of an action, i.e. you can't update the .jar from which you generate the pom. The action has
to produce a new .jar file.
I don't know -- how would you publish outside of Bazel, is there a tool to do so? Can you write a genrule / Starlark rule to wrap this
tool?
Cheers, László
I made a repository for glfw with this:
load("#bazel_tools//tools/build_defs/repo:git.bzl", "new_git_repository")
new_git_repository(
name = "glfw",
build_file = "BUILD.glfw",
remote = "https://github.com/glfw/glfw.git",
tag = "3.2.1",
)
I put BUILD.glfw in the WORKSPACE root. When I built, I saw:
no such package '#glfw//': Not a regular file: [snipped/external/BUILD.glfw
I moved BUILD.glfw to external/BUILD.glfw and it seems to work, but I couldn't find documentation about this. The docs about new_git_repository say that build_file "...is a label relative to the main workspace."; I don't see anything about 'external' there.
This is due to an inconsistent semantical difference between the native and (newer) Skylark versions of new_git_repository. To use the native new_git_repository, comment/remove the load statement:
# load("#bazel_tools//tools/build_defs/repo:git.bzl", "new_git_repository")
Assuming that new_git_repository has the same problem that http_archive has, per Bazel issue 6225 you need to refer to the BUILD file for glfw as #//:BUILD.glfw