General-purpose Starlark utility functions
load("@aspect_bazel_lib//lib:utils.bzl", "utils")
out_label = utils.to_label(out_file)consistent_label_str(ctx, label)
Generate a consistent label string for all Bazel versions.
Starting in Bazel 6, the workspace name is empty for the local workspace and there's no other way to determine it. This behavior differs from Bazel 5 where the local workspace name was fully qualified in str(label).
This utility function is meant for use in rules and requires the rule context to determine the
user's workspace name (ctx.workspace_name).
PARAMETERS
| Name | Description | Default Value |
|---|---|---|
| ctx | The rule context. | none |
| label | A Label. | none |
RETURNS
String representation of the label including the repository name if the label is from an
external repository. For labels in the user's repository the label will start with @//.
default_timeout(size, timeout)
Provide a sane default for *_test timeout attribute.
The test-encyclopedia says:
Tests may return arbitrarily fast regardless of timeout. A test is not penalized for an overgenerous timeout, although a warning may be issued: you should generally set your timeout as tight as you can without incurring any flakiness.
However Bazel's default for timeout is medium, which is dumb given this guidance.
It also says:
Tests which do not explicitly specify a timeout have one implied based on the test's size as follows
Therefore if size is specified, we should allow timeout to take its implied default.
If neither is set, then we can fix Bazel's wrong default here to avoid warnings under
--test_verbose_timeout_warnings.
This function can be used in a macro which wraps a testing rule.
PARAMETERS
| Name | Description | Default Value |
|---|---|---|
| size | the size attribute of a test target | none |
| timeout | the timeout attribute of a test target | none |
RETURNS
"short" if neither is set, otherwise timeout
file_exists(path)
Check whether a file exists.
Useful in macros to set defaults for a configuration file if it is present. This can only be called during the loading phase, not from a rule implementation.
PARAMETERS
| Name | Description | Default Value |
|---|---|---|
| path | a label, or a string which is a path relative to this package | none |
glob_directories(include, kwargs)
PARAMETERS
| Name | Description | Default Value |
|---|---|---|
| include | - |
none |
| kwargs | - |
none |
is_bazel_6_or_greater()
Detects if the Bazel version being used is greater than or equal to 6 (including Bazel 6 pre-releases and RCs).
Detecting Bazel 6 or greater is particularly useful in rules as slightly different code paths may be needed to support bzlmod which was added in Bazel 6.
Unlike the undocumented native.bazel_version, which only works in WORKSPACE and repository rules, this function can
be used in rules and BUILD files.
An alternate approach to make the Bazel version available in BUILD files and rules would be to
use the host_repo repository rule
which contains the bazel_version in the exported host struct:
WORKSPACE:
load("@aspect_bazel_lib//lib:host_repo.bzl", "host_repo")
host_repo(name = "aspect_bazel_lib_host")
BUILD.bazel:
load("@aspect_bazel_lib_host//:defs.bzl", "host")
print(host.bazel_version)
That approach, however, incurs a cost in the user's WORKSPACE.
RETURNS
True if the Bazel version being used is greater than or equal to 6 (including pre-releases and RCs)
is_bazel_7_or_greater()
Detects if the Bazel version being used is greater than or equal to 7 (including Bazel 7 pre-releases and RCs).
Unlike the undocumented native.bazel_version, which only works in WORKSPACE and repository rules, this function can
be used in rules and BUILD files.
An alternate approach to make the Bazel version available in BUILD files and rules would be to
use the host_repo repository rule
which contains the bazel_version in the exported host struct:
WORKSPACE:
load("@aspect_bazel_lib//lib:host_repo.bzl", "host_repo")
host_repo(name = "aspect_bazel_lib_host")
BUILD.bazel:
load("@aspect_bazel_lib_host//:defs.bzl", "host")
print(host.bazel_version)
That approach, however, incurs a cost in the user's WORKSPACE.
RETURNS
True if the Bazel version being used is greater than or equal to 7 (including pre-releases and RCs)
is_bzlmod_enabled()
Detect the value of the --enable_bzlmod flag
is_external_label(param)
Returns True if the given Label (or stringy version of a label) represents a target outside of the workspace
PARAMETERS
| Name | Description | Default Value |
|---|---|---|
| param | a string or label | none |
RETURNS
a bool
maybe_http_archive(kwargs)
Adapts a maybe(http_archive, ...) to look like an http_archive.
This makes WORKSPACE dependencies easier to read and update.
Typical usage looks like,
load("//lib:utils.bzl", http_archive = "maybe_http_archive")
http_archive(
name = "aspect_rules_js",
sha256 = "5bb643d9e119832a383e67f946dc752b6d719d66d1df9b46d840509ceb53e1f1",
strip_prefix = "rules_js-1.6.2",
url = "https://github.com/aspect-build/rules_js/archive/refs/tags/v1.6.2.tar.gz",
)
instead of the classic maybe pattern of,
load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")
load("@bazel_tools//tools/build_defs/repo:utils.bzl", "maybe")
maybe(
http_archive,
name = "aspect_rules_js",
sha256 = "5bb643d9e119832a383e67f946dc752b6d719d66d1df9b46d840509ceb53e1f1",
strip_prefix = "rules_js-1.6.2",
url = "https://github.com/aspect-build/rules_js/archive/refs/tags/v1.6.2.tar.gz",
)
PARAMETERS
| Name | Description | Default Value |
|---|---|---|
| kwargs | all arguments to pass-forward to http_archive | none |
path_to_workspace_root()
Returns the path to the workspace root under bazel
RETURNS
Path to the workspace root
propagate_common_binary_rule_attributes(attrs)
Returns a dict of rule parameters filtered from the input dict that only contains the ones that are common to all binary rules
These are listed in Bazel's documentation: https://bazel.build/reference/be/common-definitions#common-attributes https://bazel.build/reference/be/common-definitions#common-attributes-binary
PARAMETERS
| Name | Description | Default Value |
|---|---|---|
| attrs | Dict of parameters to filter | none |
RETURNS
The dict of parameters, containing only common binary attributes
propagate_common_rule_attributes(attrs)
Returns a dict of rule parameters filtered from the input dict that only contains the ones that are common to all rules
These are listed in Bazel's documentation: https://bazel.build/reference/be/common-definitions#common-attributes
PARAMETERS
| Name | Description | Default Value |
|---|---|---|
| attrs | Dict of parameters to filter | none |
RETURNS
The dict of parameters, containing only common attributes
propagate_common_test_rule_attributes(attrs)
Returns a dict of rule parameters filtered from the input dict that only contains the ones that are common to all test rules
These are listed in Bazel's documentation: https://bazel.build/reference/be/common-definitions#common-attributes https://bazel.build/reference/be/common-definitions#common-attributes-tests
PARAMETERS
| Name | Description | Default Value |
|---|---|---|
| attrs | Dict of parameters to filter | none |
RETURNS
The dict of parameters, containing only common test attributes
propagate_well_known_tags(tags)
Returns a list of tags filtered from the input set that only contains the ones that are considered "well known"
These are listed in Bazel's documentation: https://docs.bazel.build/versions/main/test-encyclopedia.html#tag-conventions https://docs.bazel.build/versions/main/be/common-definitions.html#common-attributes
PARAMETERS
| Name | Description | Default Value |
|---|---|---|
| tags | List of tags to filter | [] |
RETURNS
List of tags that only contains the well known set
to_label(param)
Converts a string to a Label. If Label is supplied, the same label is returned.
PARAMETERS
| Name | Description | Default Value |
|---|---|---|
| param | a string representing a label or a Label | none |
RETURNS
a Label
utils.consistent_label_str(ctx, label)
Generate a consistent label string for all Bazel versions.
Starting in Bazel 6, the workspace name is empty for the local workspace and there's no other way to determine it. This behavior differs from Bazel 5 where the local workspace name was fully qualified in str(label).
This utility function is meant for use in rules and requires the rule context to determine the
user's workspace name (ctx.workspace_name).
PARAMETERS
| Name | Description | Default Value |
|---|---|---|
| ctx | The rule context. | none |
| label | A Label. | none |
RETURNS
String representation of the label including the repository name if the label is from an
external repository. For labels in the user's repository the label will start with @//.
utils.default_timeout(size, timeout)
Provide a sane default for *_test timeout attribute.
The test-encyclopedia says:
Tests may return arbitrarily fast regardless of timeout. A test is not penalized for an overgenerous timeout, although a warning may be issued: you should generally set your timeout as tight as you can without incurring any flakiness.
However Bazel's default for timeout is medium, which is dumb given this guidance.
It also says:
Tests which do not explicitly specify a timeout have one implied based on the test's size as follows
Therefore if size is specified, we should allow timeout to take its implied default.
If neither is set, then we can fix Bazel's wrong default here to avoid warnings under
--test_verbose_timeout_warnings.
This function can be used in a macro which wraps a testing rule.
PARAMETERS
| Name | Description | Default Value |
|---|---|---|
| size | the size attribute of a test target | none |
| timeout | the timeout attribute of a test target | none |
RETURNS
"short" if neither is set, otherwise timeout
utils.file_exists(path)
Check whether a file exists.
Useful in macros to set defaults for a configuration file if it is present. This can only be called during the loading phase, not from a rule implementation.
PARAMETERS
| Name | Description | Default Value |
|---|---|---|
| path | a label, or a string which is a path relative to this package | none |
utils.glob_directories(include, kwargs)
PARAMETERS
| Name | Description | Default Value |
|---|---|---|
| include | - |
none |
| kwargs | - |
none |
utils.is_bazel_6_or_greater()
Detects if the Bazel version being used is greater than or equal to 6 (including Bazel 6 pre-releases and RCs).
Detecting Bazel 6 or greater is particularly useful in rules as slightly different code paths may be needed to support bzlmod which was added in Bazel 6.
Unlike the undocumented native.bazel_version, which only works in WORKSPACE and repository rules, this function can
be used in rules and BUILD files.
An alternate approach to make the Bazel version available in BUILD files and rules would be to
use the host_repo repository rule
which contains the bazel_version in the exported host struct:
WORKSPACE:
load("@aspect_bazel_lib//lib:host_repo.bzl", "host_repo")
host_repo(name = "aspect_bazel_lib_host")
BUILD.bazel:
load("@aspect_bazel_lib_host//:defs.bzl", "host")
print(host.bazel_version)
That approach, however, incurs a cost in the user's WORKSPACE.
RETURNS
True if the Bazel version being used is greater than or equal to 6 (including pre-releases and RCs)
utils.is_bazel_7_or_greater()
Detects if the Bazel version being used is greater than or equal to 7 (including Bazel 7 pre-releases and RCs).
Unlike the undocumented native.bazel_version, which only works in WORKSPACE and repository rules, this function can
be used in rules and BUILD files.
An alternate approach to make the Bazel version available in BUILD files and rules would be to
use the host_repo repository rule
which contains the bazel_version in the exported host struct:
WORKSPACE:
load("@aspect_bazel_lib//lib:host_repo.bzl", "host_repo")
host_repo(name = "aspect_bazel_lib_host")
BUILD.bazel:
load("@aspect_bazel_lib_host//:defs.bzl", "host")
print(host.bazel_version)
That approach, however, incurs a cost in the user's WORKSPACE.
RETURNS
True if the Bazel version being used is greater than or equal to 7 (including pre-releases and RCs)
utils.is_bzlmod_enabled()
Detect the value of the --enable_bzlmod flag
utils.is_external_label(param)
Returns True if the given Label (or stringy version of a label) represents a target outside of the workspace
PARAMETERS
| Name | Description | Default Value |
|---|---|---|
| param | a string or label | none |
RETURNS
a bool
utils.maybe_http_archive(kwargs)
Adapts a maybe(http_archive, ...) to look like an http_archive.
This makes WORKSPACE dependencies easier to read and update.
Typical usage looks like,
load("//lib:utils.bzl", http_archive = "maybe_http_archive")
http_archive(
name = "aspect_rules_js",
sha256 = "5bb643d9e119832a383e67f946dc752b6d719d66d1df9b46d840509ceb53e1f1",
strip_prefix = "rules_js-1.6.2",
url = "https://github.com/aspect-build/rules_js/archive/refs/tags/v1.6.2.tar.gz",
)
instead of the classic maybe pattern of,
load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")
load("@bazel_tools//tools/build_defs/repo:utils.bzl", "maybe")
maybe(
http_archive,
name = "aspect_rules_js",
sha256 = "5bb643d9e119832a383e67f946dc752b6d719d66d1df9b46d840509ceb53e1f1",
strip_prefix = "rules_js-1.6.2",
url = "https://github.com/aspect-build/rules_js/archive/refs/tags/v1.6.2.tar.gz",
)
PARAMETERS
| Name | Description | Default Value |
|---|---|---|
| kwargs | all arguments to pass-forward to http_archive | none |
utils.path_to_workspace_root()
Returns the path to the workspace root under bazel
RETURNS
Path to the workspace root
utils.propagate_common_binary_rule_attributes(attrs)
Returns a dict of rule parameters filtered from the input dict that only contains the ones that are common to all binary rules
These are listed in Bazel's documentation: https://bazel.build/reference/be/common-definitions#common-attributes https://bazel.build/reference/be/common-definitions#common-attributes-binary
PARAMETERS
| Name | Description | Default Value |
|---|---|---|
| attrs | Dict of parameters to filter | none |
RETURNS
The dict of parameters, containing only common binary attributes
utils.propagate_common_rule_attributes(attrs)
Returns a dict of rule parameters filtered from the input dict that only contains the ones that are common to all rules
These are listed in Bazel's documentation: https://bazel.build/reference/be/common-definitions#common-attributes
PARAMETERS
| Name | Description | Default Value |
|---|---|---|
| attrs | Dict of parameters to filter | none |
RETURNS
The dict of parameters, containing only common attributes
utils.propagate_common_test_rule_attributes(attrs)
Returns a dict of rule parameters filtered from the input dict that only contains the ones that are common to all test rules
These are listed in Bazel's documentation: https://bazel.build/reference/be/common-definitions#common-attributes https://bazel.build/reference/be/common-definitions#common-attributes-tests
PARAMETERS
| Name | Description | Default Value |
|---|---|---|
| attrs | Dict of parameters to filter | none |
RETURNS
The dict of parameters, containing only common test attributes
utils.propagate_well_known_tags(tags)
Returns a list of tags filtered from the input set that only contains the ones that are considered "well known"
These are listed in Bazel's documentation: https://docs.bazel.build/versions/main/test-encyclopedia.html#tag-conventions https://docs.bazel.build/versions/main/be/common-definitions.html#common-attributes
PARAMETERS
| Name | Description | Default Value |
|---|---|---|
| tags | List of tags to filter | [] |
RETURNS
List of tags that only contains the well known set
utils.to_label(param)
Converts a string to a Label. If Label is supplied, the same label is returned.
PARAMETERS
| Name | Description | Default Value |
|---|---|---|
| param | a string representing a label or a Label | none |
RETURNS
a Label