Nixpkgs rules for Bazel
Use Nix and the Nixpkgs package set to import external dependencies (like system packages) into Bazel hermetically. If the version of any dependency changes, Bazel will correctly rebuild targets, and only those targets that use the external dependencies that changed.
Links:
- Nix + Bazel = fully reproducible, incremental builds (blog post)
- Nix + Bazel (lightning talk)
See examples for how to use rules_nixpkgs
with different toolchains.
Rules
- nixpkgs_git_repository
- nixpkgs_http_repository
- nixpkgs_local_repository
- nixpkgs_package
- nixpkgs_flake_package
- nixpkgs_cc_configure
- nixpkgs_cc_configure_deprecated
- nixpkgs_java_configure
- nixpkgs_python_configure
- nixpkgs_python_repository
- nixpkgs_go_configure
- nixpkgs_rust_configure
- nixpkgs_sh_posix_configure
- nixpkgs_nodejs_configure
Setup
Add the following to your WORKSPACE
file, and select a $COMMIT
accordingly.
load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")
http_archive(
name = "io_tweag_rules_nixpkgs",
strip_prefix = "rules_nixpkgs-$COMMIT",
urls = ["https://github.com/tweag/rules_nixpkgs/archive/$COMMIT.tar.gz"],
)
load("@io_tweag_rules_nixpkgs//nixpkgs:repositories.bzl", "rules_nixpkgs_dependencies")
rules_nixpkgs_dependencies()
load("@io_tweag_rules_nixpkgs//nixpkgs:nixpkgs.bzl", "nixpkgs_git_repository", "nixpkgs_package", "nixpkgs_cc_configure")
load("@io_tweag_rules_nixpkgs//nixpkgs:toolchains/go.bzl", "nixpkgs_go_configure") # optional
If you use rules_nixpkgs
to configure a toolchain, then you will also need to
configure the build platform to include the
@rules_nixpkgs_core//constraints:support_nix
constraint. For
example by adding the following to .bazelrc
:
build --host_platform=@rules_nixpkgs_core//platforms:host
Example
nixpkgs_git_repository(
name = "nixpkgs",
revision = "17.09", # Any tag or commit hash
sha256 = "" # optional sha to verify package integrity!
)
nixpkgs_package(
name = "hello",
repositories = { "nixpkgs": "@nixpkgs//:default.nix" }
)
Migration from older releases
path
Attribute (removed in 0.3)
path
was an attribute from the early days of rules_nixpkgs
, and
its ability to reference arbitrary paths is a danger to build hermeticity.
Replace it with either nixpkgs_git_repository
if you need
a specific version of nixpkgs
. If you absolutely must depend on a
local folder, use Bazel's
local_repository
workspace rule.
Both approaches work well with the repositories
attribute of nixpkgs_package
.
local_repository(
name = "local-nixpkgs",
path = "/path/to/nixpkgs",
)
nixpkgs_package(
name = "somepackage",
repositories = {
"nixpkgs": "@local-nixpkgs//:default.nix",
},
)
Reference documentation
nixpkgs_cc_configure
nixpkgs_cc_configure(name, attribute_path, nix_file, nix_file_content, nix_file_deps, repositories, repository, nixopts, quiet, fail_not_supported, exec_constraints, target_constraints, register, cc_lang)
Use a CC toolchain from Nixpkgs. No-op if not a nix-based platform.
By default, Bazel auto-configures a CC toolchain from commands (e.g.
gcc
) available in the environment. To make builds more hermetic, use
this rule to specify explicitly which commands the toolchain should use.
Specifically, it builds a Nix derivation that provides the CC toolchain
tools in the bin/
path and constructs a CC toolchain that uses those
tools. Tools that aren't found are replaced by ${coreutils}/bin/false
.
You can inspect the resulting @<name>_info//:CC_TOOLCHAIN_INFO
to see
which tools were discovered.
If you specify the nix_file
or nix_file_content
argument, the CC
toolchain is discovered by evaluating the corresponding expression. In
addition, you may use the attribute_path
argument to select an attribute
from the result of the expression to use as the CC toolchain (see example below).
If neither the nix_file
nor nix_file_content
argument is used, the
toolchain is discovered from the stdenv.cc
and the stdenv.cc.bintools
attributes of the given <nixpkgs>
repository.
# use GCC 11
nixpkgs_cc_configure(
repository = "@nixpkgs",
nix_file_content = "(import <nixpkgs> {}).gcc11",
)
# use GCC 11 (same result as above)
nixpkgs_cc_configure(
repository = "@nixpkgs",
attribute_path = "gcc11",
nix_file_content = "import <nixpkgs> {}",
)
# alternate usage without specifying `nix_file` or `nix_file_content`
nixpkgs_cc_configure(
repository = "@nixpkgs",
attribute_path = "gcc11",
)
# use the `stdenv.cc` compiler (the default of the given @nixpkgs repository)
nixpkgs_cc_configure(
repository = "@nixpkgs",
)
This rule depends on rules_cc
.
Note:
You need to configure --crosstool_top=@<name>//:toolchain
to activate
this toolchain.
Parameters
name |
optional.
default is |
attribute_path |
optional.
default is
optional, string, Obtain the toolchain from the Nix expression under this attribute path. Uses default repository if no |
nix_file |
optional.
default is
optional, Label, Obtain the toolchain from the Nix expression defined in this file. Specify only one of |
nix_file_content |
optional.
default is
optional, string, Obtain the toolchain from the given Nix expression. Specify only one of |
nix_file_deps |
optional.
default is
optional, list of Label, Additional files that the Nix expression depends on. |
repositories |
optional.
default is
dict of Label to string, Provides |
repository |
optional.
default is
Label, Provides |
nixopts |
optional.
default is
optional, list of string, Extra flags to pass when calling Nix. See |
quiet |
optional.
default is
bool, Whether to hide |
fail_not_supported |
optional.
default is
bool, Whether to fail if |
exec_constraints |
optional.
default is
Constraints for the execution platform. |
target_constraints |
optional.
default is
Constraints for the target platform. |
register |
optional.
default is
bool, enabled by default, Whether to register (with |
cc_lang |
optional.
default is
string, |
nixpkgs_cc_configure_deprecated
nixpkgs_cc_configure_deprecated(repository, repositories, nix_file, nix_file_deps, nix_file_content, nixopts)
Use a CC toolchain from Nixpkgs. No-op if not a nix-based platform.
Tells Bazel to use compilers and linkers from Nixpkgs for the CC toolchain.
By default, Bazel auto-configures a CC toolchain from commands available in
the environment (e.g. gcc
). Overriding this autodetection makes builds
more hermetic and is considered a best practice.
Example
nixpkgs_cc_configure(repository = "@nixpkgs//:default.nix")
Parameters
repository |
optional.
default is
A repository label identifying which Nixpkgs to use.
Equivalent to |
repositories |
optional.
default is
A dictionary mapping Setting it to
for example would replace all instances of Specify one of |
nix_file |
optional.
default is
An expression for a Nix environment derivation.
The environment should expose all the commands that make up a CC
toolchain ( |
nix_file_deps |
optional.
default is
Dependencies of |
nix_file_content |
optional.
default is
An expression for a Nix environment derivation. |
nixopts |
optional.
default is
Options to forward to the nix command. |
nixpkgs_flake_package
nixpkgs_flake_package(name, nix_flake_file, nix_flake_lock_file, nix_flake_file_deps, package, build_file, build_file_content, nixopts, quiet, fail_not_supported, kwargs)
Make the content of a local Nix Flake package available in the Bazel workspace.
Parameters
name |
required.
A unique name for this repository. |
nix_flake_file |
required.
Label to |
nix_flake_lock_file |
required.
Label to |
nix_flake_file_deps |
optional.
default is
Additional dependencies of |
package |
optional.
default is
Nix Flake package to make available. The default package will be used if not specified. |
build_file |
optional.
default is
The file to use as the BUILD file for this repository. See |
build_file_content |
optional.
default is
Like |
nixopts |
optional.
default is
Extra flags to pass when calling Nix. See |
quiet |
optional.
default is
Whether to hide the output of the Nix command. |
fail_not_supported |
optional.
default is
If set to |
kwargs |
optional. |
nixpkgs_git_repository
nixpkgs_git_repository(name, revision, remote, sha256, kwargs)
Name a specific revision of Nixpkgs on GitHub or a local checkout.
Parameters
name |
required.
String A unique name for this repository. |
revision |
required.
String Git commit hash or tag identifying the version of Nixpkgs to use. |
remote |
optional.
default is
String The URI of the remote Git repository. This must be a HTTP URL. There is currently no support for authentication. Defaults to upstream nixpkgs. |
sha256 |
optional.
default is
String The SHA256 used to verify the integrity of the repository. |
kwargs |
optional.
Additional arguments to forward to the underlying repository rule. |
nixpkgs_http_repository
nixpkgs_http_repository(name, url, urls, auth, strip_prefix, integrity, sha256, kwargs)
Download a Nixpkgs repository over HTTP.
Parameters
name |
required.
String A unique name for this repository. |
url |
optional.
default is
String A URL to download the repository from. This must be a file, http or https URL. Redirections are followed. More flexibility can be achieved by the urls parameter that allows to specify alternative URLs to fetch from. |
urls |
optional.
default is
List of String A list of URLs to download the repository from. Each entry must be a file, http or https URL. Redirections are followed. URLs are tried in order until one succeeds, so you should list local mirrors first. If all downloads fail, the rule will fail. |
auth |
optional.
default is
Dict of String An optional dict mapping host names to custom authorization patterns. If a URL's host name is present in this dict the value will be used as a pattern when generating the authorization header for the http request. This enables the use of custom authorization schemes used in a lot of common cloud storage providers. The pattern currently supports 2 tokens: Example attribute and netrc for a http download to an oauth2 enabled API using a bearer token: auth_patterns = { "storage.cloudprovider.com": "Bearer <password>" } netrc: machine storage.cloudprovider.com password RANDOM-TOKEN The final HTTP request would have the following header: Authorization: Bearer RANDOM-TOKEN |
strip_prefix |
optional.
default is
String A directory prefix to strip from the extracted files. Many archives contain a top-level directory that contains all of the useful files in archive. This field can be used to strip it from all of the extracted files. For example, suppose you are using Note that if there are files outside of this directory, they will be
discarded and inaccessible (e.g., a top-level license file). This includes
files/directories that start with the prefix but are not in the directory
(e.g., |
integrity |
optional.
default is
String Expected checksum in Subresource Integrity format of the file downloaded. This must match the checksum of the file downloaded. It is a security risk
to omit the checksum as remote files can change. At best omitting this
field will make your build non-hermetic. It is optional to make development
easier but either this attribute or |
sha256 |
optional.
default is
String The expected SHA-256 of the file downloaded. This must match the SHA-256 of the file downloaded. It is a security risk to omit the SHA-256 as remote files can change. At best omitting this field will make your build non-hermetic. It is optional to make development easier but should be set before shipping. |
kwargs |
optional.
Additional arguments to forward to the underlying repository rule. |
nixpkgs_java_configure
nixpkgs_java_configure(name, attribute_path, java_home_path, repository, repositories, nix_file, nix_file_content, nix_file_deps, nixopts, fail_not_supported, quiet, toolchain, register, toolchain_name, toolchain_version, exec_constraints, target_constraints)
Define a Java runtime provided by nixpkgs.
Creates a nixpkgs_package
for a java_runtime
instance. Optionally,
you can also create & register a Java toolchain. This only works with Bazel >= 5.0
Bazel can use this instance to run JVM binaries and tests, refer to the
Bazel documentation for details.
Example
Bazel 4
Add the following to your WORKSPACE
file to import a JDK from nixpkgs:
load("@io_tweag_rules_nixpkgs//nixpkgs:nixpkgs.bzl", "nixpkgs_java_configure")
nixpkgs_java_configure(
attribute_path = "jdk11.home",
repository = "@nixpkgs",
)
Add the following configuration to .bazelrc
to enable this Java runtime:
build --javabase=@nixpkgs_java_runtime//:runtime
build --host_javabase=@nixpkgs_java_runtime//:runtime
# Adjust this to match the Java version provided by this runtime.
# See `bazel query 'kind(java_toolchain, @bazel_tools//tools/jdk:all)'` for available options.
build --java_toolchain=@bazel_tools//tools/jdk:toolchain_java11
build --host_java_toolchain=@bazel_tools//tools/jdk:toolchain_java11
Bazel 5
Add the following to your WORKSPACE
file to import a JDK from nixpkgs:
load("@io_tweag_rules_nixpkgs//nixpkgs:nixpkgs.bzl", "nixpkgs_java_configure")
nixpkgs_java_configure(
attribute_path = "jdk11.home",
repository = "@nixpkgs",
toolchain = True,
toolchain_name = "nixpkgs_java",
toolchain_version = "11",
)
Add the following configuration to .bazelrc
to enable this Java runtime:
build --host_platform=@io_tweag_rules_nixpkgs//nixpkgs/platforms:host
build --java_runtime_version=nixpkgs_java
build --tool_java_runtime_version=nixpkgs_java
Bazel 6
Add the following to your WORKSPACE
file to import a JDK from nixpkgs:
load("@io_tweag_rules_nixpkgs//nixpkgs:nixpkgs.bzl", "nixpkgs_java_configure")
nixpkgs_java_configure(
attribute_path = "jdk11.home",
repository = "@nixpkgs",
toolchain = True,
toolchain_name = "nixpkgs_java",
toolchain_version = "11",
)
Add the following configuration to .bazelrc
to enable this Java runtime:
build --host_platform=@io_tweag_rules_nixpkgs//nixpkgs/platforms:host
build --java_runtime_version=nixpkgs_java_11
build --tool_java_runtime_version=nixpkgs_java_11
build --java_language_version=11
build --tool_java_language_version=11
Parameters
name |
optional.
default is
The name-prefix for the created external repositories. |
attribute_path |
optional.
default is
string, The nixpkgs attribute path for |
java_home_path |
optional.
default is
optional, string, The path to |
repository |
optional.
default is
See |
repositories |
optional.
default is
See |
nix_file |
optional.
default is
optional, Label, Obtain the runtime from the Nix expression defined in this file. Specify only one of |
nix_file_content |
optional.
default is
optional, string, Obtain the runtime from the given Nix expression. Specify only one of |
nix_file_deps |
optional.
default is
See |
nixopts |
optional.
default is
See |
fail_not_supported |
optional.
default is
See |
quiet |
optional.
default is
See |
toolchain |
optional.
default is
Create a Bazel toolchain based on the Java runtime. |
register |
optional.
default is
Register the created toolchain. Requires |
toolchain_name |
optional.
default is
The name of the toolchain that can be used in --java_runtime_version. |
toolchain_version |
optional.
default is
The version of the toolchain that can be used in --java_runtime_version. |
exec_constraints |
optional.
default is
Constraints for the execution platform. |
target_constraints |
optional.
default is
Constraints for the target platform. |
nixpkgs_local_repository
nixpkgs_local_repository(name, nix_file, nix_file_deps, nix_file_content, nix_flake_lock_file, kwargs)
Create an external repository representing the content of Nixpkgs.
Based on a Nix expression stored locally or provided inline. One of
nix_file
or nix_file_content
must be provided.
Parameters
name |
required.
String A unique name for this repository. |
nix_file |
optional.
default is
Label A file containing an expression for a Nix derivation. |
nix_file_deps |
optional.
default is
List of labels Dependencies of |
nix_file_content |
optional.
default is
String An expression for a Nix derivation. |
nix_flake_lock_file |
optional.
default is
String A flake lock file that can be used on the provided nixpkgs repository. |
kwargs |
optional.
Additional arguments to forward to the underlying repository rule. |
nixpkgs_nodejs_configure
nixpkgs_nodejs_configure(name, attribute_path, repository, repositories, nix_platform, nix_file, nix_file_content, nix_file_deps, nixopts, fail_not_supported, quiet, exec_constraints, target_constraints, register)
Parameters
name |
optional.
default is |
attribute_path |
optional.
default is |
repository |
optional.
default is |
repositories |
optional.
default is |
nix_platform |
optional.
default is |
nix_file |
optional.
default is |
nix_file_content |
optional.
default is |
nix_file_deps |
optional.
default is |
nixopts |
optional.
default is |
fail_not_supported |
optional.
default is |
quiet |
optional.
default is |
exec_constraints |
optional.
default is |
target_constraints |
optional.
default is |
register |
optional.
default is |
nixpkgs_nodejs_configure_platforms
nixpkgs_nodejs_configure_platforms(name, platforms_mapping, attribute_path, repository, repositories, nix_platform, nix_file, nix_file_content, nix_file_deps, nixopts, fail_not_supported, quiet, exec_constraints, target_constraints, register, kwargs)
Runs nixpkgs_nodejs_configure for each platform.
Since rules_nodejs adds platform suffix to repository name, this can be helpful if one wants to use npm_install and reference js dependencies from npm repo. See the example directory.
Parameters
name |
optional.
default is |
platforms_mapping |
optional.
default is
struct describing mapping between nix platform and rules_nodejs bazel platform with target and exec constraints |
attribute_path |
optional.
default is |
repository |
optional.
default is |
repositories |
optional.
default is |
nix_platform |
optional.
default is |
nix_file |
optional.
default is |
nix_file_content |
optional.
default is |
nix_file_deps |
optional.
default is |
nixopts |
optional.
default is |
fail_not_supported |
optional.
default is |
quiet |
optional.
default is |
exec_constraints |
optional.
default is |
target_constraints |
optional.
default is |
register |
optional.
default is |
kwargs |
optional. |
nixpkgs_package
nixpkgs_package(name, attribute_path, nix_file, nix_file_deps, nix_file_content, repository, repositories, build_file, build_file_content, nixopts, quiet, fail_not_supported, kwargs)
Make the content of a Nixpkgs package available in the Bazel workspace.
If repositories
is not specified, you must provide a nixpkgs clone in nix_file
or nix_file_content
.
Parameters
name |
required.
A unique name for this repository. |
attribute_path |
optional.
default is
Select an attribute from the top-level Nix expression being evaluated. The attribute path is a sequence of attribute names separated by dots. |
nix_file |
optional.
default is
A file containing an expression for a Nix derivation. |
nix_file_deps |
optional.
default is
Dependencies of |
nix_file_content |
optional.
default is
An expression for a Nix derivation. |
repository |
optional.
default is
A repository label identifying which Nixpkgs to use. Equivalent to |
repositories |
optional.
default is
A dictionary mapping Setting it to
for example would replace all instances of Specify one of |
build_file |
optional.
default is
The file to use as the BUILD file for this repository. Its contents are copied into the file For common use cases we provide filegroups that expose certain files as targets:
If you need different files from the nix package, you can reference them like this:
|
build_file_content |
optional.
default is
Like |
nixopts |
optional.
default is
Extra flags to pass when calling Nix. Subject to location expansion, any instance of Note, labels to external workspaces will resolve to paths that contain |
quiet |
optional.
default is
Whether to hide the output of the Nix command. |
fail_not_supported |
optional.
default is
If set to |
kwargs |
optional. |
nixpkgs_python_configure
nixpkgs_python_configure(name, python2_attribute_path, python2_bin_path, python3_attribute_path, python3_bin_path, repository, repositories, nix_file_deps, nixopts, fail_not_supported, quiet, exec_constraints, target_constraints, register)
Define and register a Python toolchain provided by nixpkgs.
Creates nixpkgs_package
s for Python 2 or 3 py_runtime
instances and a
corresponding py_runtime_pair
and toolchain
. The toolchain is
automatically registered and uses the constraint:
"@io_tweag_rules_nixpkgs//nixpkgs/constraints:support_nix"
Parameters
name |
optional.
default is
The name-prefix for the created external repositories. |
python2_attribute_path |
optional.
default is
The nixpkgs attribute path for python2. |
python2_bin_path |
optional.
default is
The path to the interpreter within the package. |
python3_attribute_path |
optional.
default is
The nixpkgs attribute path for python3. |
python3_bin_path |
optional.
default is
The path to the interpreter within the package. |
repository |
optional.
default is
See |
repositories |
optional.
default is
See |
nix_file_deps |
optional.
default is
See |
nixopts |
optional.
default is
See |
fail_not_supported |
optional.
default is
See |
quiet |
optional.
default is
See |
exec_constraints |
optional.
default is
Constraints for the execution platform. |
target_constraints |
optional.
default is
Constraints for the target platform. |
register |
optional.
default is |
nixpkgs_python_repository
nixpkgs_python_repository(name, repository, repositories, nix_file, nix_file_deps, quiet)
Define a collection of python packages based on a nix file.
The only entry point is a nix_file
which should expose a pkgs
and a python
attributes. python
is the
python interpreter, and pkgs
a set of python packages that will be made
available to bazel.
pkgs
are built by this rule. It is
therefore not a good idea to expose something as big as pkgs.python3
as
provided by nixpkgs.
This rule is instead intended to expose an ad-hoc set of packages for your project, as can be built by poetry2nix, mach-nix, dream2nix or by manually picking the python packages you need from nixpkgs.
The format is generic to support the many ways to generate such packages
sets with nixpkgs. See our python tests
and
examples to get started.
This rule is intended to mimic as closely as possible the rules_python
API.
nixpkgs_python_repository
should be a drop-in replacement of pip_parse
.
As such, it also provides a requirement
function.
requirement
fucntion inherits the same advantages and
limitations as the one in rules_python. All the function does is create a
label of the form @{nixpkgs_python_repository_name}//:{package_name}
.
While depending on such a label directly will work, the layout may change
in the future. To be on the safe side, define and import your own
requirement
function if you need to play with these labels.
pname
attribute of the corresponding nix package. These may vary slightly from
names used by rules_python. Should this be a problem, you can provide you
own requirement
function, for example one that lowercases its argument.
Parameters
name |
required.
The name for the created package set. |
repository |
optional.
default is
See |
repositories |
optional.
default is
See |
nix_file |
optional.
default is
See |
nix_file_deps |
optional.
default is
See |
quiet |
optional.
default is
See |
nixpkgs_rust_configure
nixpkgs_rust_configure(name, default_edition, repository, repositories, nix_file, nix_file_deps, nix_file_content, nixopts, fail_not_supported, quiet, exec_constraints, target_constraints, register)
Parameters
name |
optional.
default is |
default_edition |
optional.
default is |
repository |
optional.
default is |
repositories |
optional.
default is |
nix_file |
optional.
default is |
nix_file_deps |
optional.
default is |
nix_file_content |
optional.
default is |
nixopts |
optional.
default is |
fail_not_supported |
optional.
default is |
quiet |
optional.
default is |
exec_constraints |
optional.
default is |
target_constraints |
optional.
default is |
register |
optional.
default is |
nixpkgs_sh_posix_configure
nixpkgs_sh_posix_configure(name, packages, exec_constraints, register, kwargs)
Create a POSIX toolchain from nixpkgs.
Loads the given Nix packages, scans them for standard Unix tools, and
generates a corresponding sh_posix_toolchain
.
Make sure to call nixpkgs_sh_posix_configure
before sh_posix_configure
,
if you use both. Otherwise, the local toolchain will always be chosen in
favor of the nixpkgs one.
Parameters
name |
optional.
default is
Name prefix for the generated repositories. |
packages |
optional.
default is
List of Nix attribute paths to draw Unix tools from. |
exec_constraints |
optional.
default is
Constraints for the execution platform. |
register |
optional.
default is
Automatically register the generated toolchain if set to True. |
kwargs |
optional. |