# Copyright 2017 The Bazel Authors. All rights reserved.

#

# Licensed under the Apache License, Version 2.0 (the "License");

# you may not use this file except in compliance with the License.

# You may obtain a copy of the License at

#

# http://www.apache.org/licenses/LICENSE-2.0

#

# Unless required by applicable law or agreed to in writing, software

# distributed under the License is distributed on an "AS IS" BASIS,

# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

# See the License for the specific language governing permissions and

# limitations under the License.

"""Import pip requirements into Bazel."""

def _pip_import_impl(repository_ctx):

"""Core implementation of pip_import."""

# Add an empty top-level BUILD file.

# This is because Bazel requires BUILD files along all paths accessed

# via //this/sort/of:path and we wouldn't be able to load our generated

# requirements.bzl without it.

repository_ctx.file("BUILD", "")

# To see the output, pass: quiet=False

result = repository_ctx.execute([

"python",

repository_ctx.path(repository_ctx.attr._script),

"--name",

repository_ctx.attr.name,

"--input",

repository_ctx.path(repository_ctx.attr.requirements),

"--output",

repository_ctx.path("requirements.bzl"),

"--directory",

repository_ctx.path(""),

])

if result.return_code:

fail("pip_import failed: %s (%s)" % (result.stdout, result.stderr))

pip_import = repository_rule(

attrs = {

"requirements": attr.label(

mandatory = True,

allow_single_file = True,

),

"_script": attr.label(

executable = True,

default = Label("//tools:piptool.par"),

cfg = "host",

),

},

implementation = _pip_import_impl,

)

"""A rule for importing <code>requirements.txt</code> dependencies into Bazel.

This rule imports a <code>requirements.txt</code> file and generates a new

<code>requirements.bzl</code> file. This is used via the <code>WORKSPACE</code>

pattern:

<pre><code>pip_import(

name = "foo",

requirements = ":requirements.txt",

)

load("@foo//:requirements.bzl", "pip_install")

pip_install()

</code></pre>

You can then reference imported dependencies from your <code>BUILD</code>

file with:

<pre><code>load("@foo//:requirements.bzl", "requirement")

py_library(

name = "bar",

...

deps = [

"//my/other:dep",

requirement("futures"),

requirement("mock"),

],

)

</code></pre>

Or alternatively:

<pre><code>load("@foo//:requirements.bzl", "all_requirements")

py_binary(

name = "baz",

...

deps = [

":foo",

] + all_requirements,

)

</code></pre>

Args:

requirements: The label of a requirements.txt file.

"""

def pip_repositories():

"""Pull in dependencies needed to use the pip rules.

At the moment this is a placeholder, in that it does not actually pull in

any dependencies. However, it does do some validation checking.

"""

# As a side effect of migrating our canonical workspace name from

# "@io_bazel_rules_python" to "@rules_python" (#203), users who still

# imported us by the old name would get a confusing error about a

# repository dependency cycle in their workspace. (The cycle is likely

# related to the fact that our repo name is hardcoded into the template

# in piptool.py.)

#

# To produce a more informative error message in this situation, we

# fail-fast here if we detect that we're not being imported by the new

# name. (I believe we have always had the requirement that we're imported

# by the canonical name, because of the aforementioned hardcoding.)

#

# Users who, against best practice, do not call pip_repositories() in their

# workspace will not benefit from this check.

if "rules_python" not in native.existing_rules():

message = "=" * 79 + """\n\

It appears that you are trying to import rules_python without using its

canonical name, "@rules_python". This does not work. Please change your

WORKSPACE file to import this repo with `name = "rules_python"` instead.

"""

if "io_bazel_rules_python" in native.existing_rules():

message += """\n\

Note that the previous name of "@io_bazel_rules_python" is no longer used.

See https://github.com/bazelbuild/rules_python/issues/203 for context.

"""

message += "=" * 79

fail(message)