Aquery (action graph query)
Overview
The aquery
command allows you to query for actions in your build graph.
It operates on the post-analysis Configured Target Graph and exposes
information about Actions, Artifacts and their relationships.
aquery
is useful when we are interested in the properties of the Actions/Artifacts
generated from the Configured Target Graph. For example, the actual commands run
and their inputs/outputs/mnemonics.
The tool accepts several command-line options. Notably, the aquery command runs on top of a regular Bazel build and inherits the set of options available during a build.
It supports the same set of functions that is also available to traditional
query
but siblings
, buildfiles
and
tests
.
An example aquery
output (without specific details):
$ bazel aquery 'deps(//some:label)' action 'Writing file some_file_name' Mnemonic: ... Target: ... Configuration: ... ActionKey: ... Inputs: [...] Outputs: [...]
Basic syntax
A simple example of the syntax for aquery
is as follows:
bazel aquery "aquery_function(function(//target))"
The query expression (in quotes) consists of the following:
-
aquery_function(...)
: functions specific toaquery
. More details below. -
function(...)
: the standard functions as traditionalquery
. -
//target
is the label to the interested target.
# aquery examples: # Get the action graph generated while building //src/target_a $ bazel aquery '//src/target_a' # Get the action graph generated while building all dependencies of //src/target_a $ bazel aquery 'deps(//src/target_a)' # Get the action graph generated while building all dependencies of //src/target_a # whose inputs filenames match the regex ".*cpp". $ bazel aquery 'inputs(".*cpp", deps(//src/target_a))'
Aquery functions
There are currently 3 aquery
functions:
inputs
: filter actions by inputs.outputs
: filter actions by outputsmnemonic
: filter actions by mnemonic
expr ::= inputs(word, expr)
The inputs
operator returns the actions generated from building expr
,
whose input filenames match the regex provided by word
.
$ bazel aquery 'inputs(".*cpp", deps(//src/target_a))'
outputs
and mnemonic
functions share a similar syntax.
You can also combine functions to achieve the AND operation. For example:
$ bazel aquery 'mnemonic("Cpp.*", (inputs(".*cpp", inputs("foo.*", //src/target_a))))'
The above command would find all actions involved in building //src/target_a
,
whose mnemonics match "Cpp.*"
and inputs match the patterns
".*cpp"
and "foo.*"
.
Important: aquery functions can't be nested inside non-aquery functions
- Conceptually this makes sense since the output of aquery functions is Actions, not Configured Targets.
-
An example of the syntax error produced:
$ bazel aquery 'deps(inputs(".*cpp", //src/target_a))' ERROR: aquery filter functions (inputs, outputs, mnemonic) produce actions, and therefore can't be the input of other function types: deps deps(inputs(".*cpp", //src/target_a))
Options
Build options
aquery
runs on top of a regular Bazel build and thus inherits the set of
options
available during a build.
Aquery options
--output=(text|proto|textproto), default=text
The default output format (text
) is human-readable,
use proto
or textproto
for machine-readable format.
--include_commandline, default=true
Includes the content of the action command lines in the output (potentially large).
--include_artifacts, default=true
Includes names of the action inputs and outputs in the output (potentially large).
--include_aspects, default=false
Whether to include Aspect-generated actions in the output.
--include_param_files, default=false
Include the content of the param files used in the command (potentially large).
Warning: Enabling this flag will automatically enable the --include_commandline
flag.
--skyframe_state, default=false
Without performing extra analysis, dump the current Action Graph from Skyframe.
Note: Specifying a target with --skyframe_state
is currently not supported.
This flag is only available with --output=proto
or --output=textproto
.
Other tools and features
Querying against the state of Skyframe
Skyframe is the evaluation and incrementality model of Bazel. On each instance of Bazel server, Skyframe stores the dependency graph constructed from the previous runs of the Analysis phase.
In some cases, it is useful to query the Action Graph currently on Skyframe. An example use case would be:
- Run
bazel build //target_a
- Run
bazel build //target_b
- File
foo.out
was generated.
As a Bazel user, I want to determine if foo.out
was generated from building
//target_a
or //target_b
.
One could run bazel aquery 'outputs("foo.out", //target_a)'
and
bazel aquery 'outputs("foo.out", //target_b)'
to figure out the action responsible
for creating foo.out
, and in turn the target. However, the number of different
targets previously built can be larger than 2, which makes running multiple aquery
commands a hassle.
As an alternative, the --skyframe_state
flag can be used:
# List all actions on Skyframe's action graph $ bazel aquery --output=proto --skyframe_state # or # List all actions on Skyframe's action graph, whose output matches "foo.out" $ bazel aquery --output=proto --skyframe_state 'outputs("foo.out")'
With --skyframe_state
mode, aquery
takes the content of the Action Graph
that Skyframe keeps on the current instance of Bazel, (optionally) performs filtering on it and
outputs the content, without re-running the analysis phase.
Special considerations
Output format
--skyframe_state
is currently only available for --output=proto
and --output=textproto
Non-inclusion of target labels in the query expression
Currently, --skyframe_state
queries the whole action graph that exists on Skyframe,
regardless of the targets. Having the target label specified in the query together with
--skyframe_state
is considered a syntax error:
# WRONG: Target Included $ bazel aquery --output=proto --skyframe_state //target_a ERROR: Error while parsing '//target_a)': Specifying build target(s) [//target_a] with --skyframe_state is currently not supported. # WRONG: Target Included $ bazel aquery --output=proto --skyframe_state 'inputs(".*.java", //target_a)' ERROR: Error while parsing '//target_a)': Specifying build target(s) [//target_a] with --skyframe_state is currently not supported. # CORRECT: Without Target $ bazel aquery --output=proto --skyframe_state $ bazel aquery --output=proto --skyframe_state 'inputs(".*.java")'
Comparing aquery outputs
You can compare the outputs of two different aquery invocations using the aquery_differ
tool.
For instance: when you make some changes to your rule definition and want to verify that the
command lines being run did not change. aquery_differ
is the tool for that.
The tool is available in the bazelbuild/bazel repository. To use it, clone the repository to your local machine. An example usage:
$ bazel run //tools/aquery_differ -- \ --before=/path/to/before.proto \ --after=/path/to/after.proto \ --input_type=proto \ --attrs=cmdline \ --attrs=inputs
The above command returns the difference between the before
and after
aquery outputs:
which actions were present in one but not the other, which actions have different
command line/inputs in each aquery output, ...). The result of running the above command would be:
Aquery output 'after' change contains an action that generates the following outputs that aquery output 'before' change doesn't: ... /list of output files/ ... [cmdline] Difference in the action that generates the following output(s): /path/to/abc.out --- /path/to/before.proto +++ /path/to/after.proto @@ -1,3 +1,3 @@ ... /cmdline diff, in unified diff format/ ...
Command options
--before, --after
: The aquery output files to be compared
--input_type=(proto|text_proto), default=proto
: the format of the input
files. We currently support proto
and textproto
aquery output.
--attrs=(cmdline|inputs), default=cmdline
: the attributes of actions
to be compared.
Aspect-on-aspect
It is possible for Aspects to be applied on top of each other. The aquery output of the action generated by these Aspects would then include the Aspect path, which is the sequence of Aspects applied to the target which generated the action.
An example of Aspect-on-Aspect:
t0 ^ | <- a1 t1 ^ | <- a2 t2
Let ti be a target of rule ri, which applies an Aspect ai to its dependencies.
Assume that a2 generates an action X when applied to target t0. The text output of
bazel aquery --include_aspects 'deps(//t2)'
for action X would be:
action ... Mnemonic: ... Target: //my_pkg:t0 Configuration: ... AspectDescriptors: [//my_pkg:rule.bzl%a2(foo=...) -> //my_pkg:rule.bzl%a1(bar=...)] ...
This means that action X
was generated by Aspect a2
applied onto
a1(t0)
, where a1(t0)
is the result of Aspect a1
applied
onto target t0
.
Each AspectDescriptor
has the following format:
AspectClass([param=value,...])
AspectClass
could be the name of the Aspect class (for native Aspects) or
bzl_file%aspect_name
(for Starlark Aspects). AspectDescriptor
are
sorted in topological order of the
dependency graph.
Known issues
Handling Shared Actions
Sometimes actions are
shared
between configured targets.
In the execution phase, those shared actions are
simply considered as one and only executed once.
However, aquery operates on the pre-execution, post-analysis action graph, and hence treats these
like separate actions whose output Artifacts have the exact same execPath
. As a result,
we'll have equivalent Artifacts appearing duplicated.
The list of aquery issues/planned features can be found on GitHub.
Updates
Please contact twerth@google.com and leba@google.com for any issue/feature request.