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Readme.md

rules_cpan e2e example

Demonstrates how to use rules_cpan by building https://github.com/linux-test-project/lcov.

cpanfile

Some projects already deliver a cpanfile.

In the case of Lcov the Perl dependencies are just listed in the Readme: https://github.com/linux-test-project/lcov/blob/v2.1/README#L116.
It's straightforward to convert this into requires 'Capture::Tiny'; (and so on) for the cpanfile.

cpanfile.snapshot

rules_cpan needs a cpanfile.snapshot as input.

The user needs to install and run Carton manually to generate this file.

This will actually install the dependencies into a local directory. We just remove this directory afterwards.

curl -L https://cpanmin.us | perl - --sudo App::cpanminus
sudo cpanm --notest Carton

cd e2e
carton

rm -rf local

cpanfile.snapshot.lock.json

The cpanfile.snapshot.lock.json is generated by lock.py of rules_cpan:

bazel run @rules_cpan//lock -- cpanfile.snapshot cpanfile.snapshot.lock.json

It contains the URLs and checksums of the cpan dependencies that will be downloaded by Bazel.

MODULE.bazel

Until bazelbuild/rules_perl#62 is merged you need to add a rules_perl dependency with a git_override:

bazel_dep(name = "rules_perl")
git_override(
    module_name = "rules_perl",
    remote = "https://github.com/lalten/rules_perl",
    commit = "973efb79defe0c417aa9655ac24a09148d599e9e",
)

Now you can use the cpan extension of rules_cpan to generate the perl_library targets.

cpan = use_extension("@rules_cpan//cpan:extensions.bzl", "cpan")
cpan.install(
    name = "cpan_deps",
    lock = "//:cpanfile.snapshot.lock.json",
)
use_repo(cpan, "cpan_deps")

In this example we don't have any Perl code of our own and just pull in the latest Lcov release as http_archive.

BUILD

Now we can finally depend on the cpan targets in our BUILD file:

load("@rules_perl//perl:perl.bzl", "perl_binary", "perl_library")

perl_library(
    name = "liblcov",
    srcs = glob(["lib/**/*"]),
    deps = ["@cpan_deps"],
)

Testing

In this example we have an integration test that runs the gehtml --version:

bazel test //:integration_test --test_output=all