bazelbuild/bazel

Support `build_file` or `build_file_content` for `http_file`

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#25,383 opened on Feb 25, 2025

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P2help wantedteam-ExternalDepstype: feature request

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Description

Description of the feature request:

I would like to use http_file to download a single proto file.

http_file(
    name = "fake_proto",
    sha256 = "abc1234",
    url = "https://raw.githubusercontent.com/myorg/myrepo/src/path/probo/fake.proto
    downloaded_file_path = "fake.proto",
)

I cannot use this natively in a proto_library due to the following via https://github.com/protocolbuffers/protobuf/blob/2d6ab3ce45f85af6bffd694659148062ba9aecde/bazel/private/bazel_proto_library_rule.bzl#L24C5-L24C24

Error in fail: Proto source with label '@@_main~_repo_rules~fake_proto//file:fake.proto' must be in same package as consuming rule.

You can get around this in two ways:

A dummy genrule to copy it to local package

genrule(
    name = "fake_proto_file",
    srcs = ["@fake_proto//file:fake.proto"],
    outs = ["fake.proto"],
    cmd = """
        cp $< $@
    """,
)

http_archive with custom build_file The custom build_file_content can create the proto_library and therefore be in the same package.

Both of these feels unnecessary; pulling in protobuf files should be a straightforward UX in Bazel.

Contributor guide

Research direction
Examine the current implementation of http file in Bazel's rules (likely in rules repository or similar). Understand how build file and build file content are handled in other rules like http archive. Then inspect the proto library rule's source restriction that requires proto files to be in the same package. Propose adding build file or build file content support to http file to allow users to define a build file for the downloaded file, enabling proto library usage directly.
Tech stack
java
Domain
build system
Issue type
Feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-2 days
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
Bazel
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
60