thii / rules_swiftlint

Run SwiftLint in your Bazel build efficiently.

rules_swiftlint

Run SwiftLint in your Bazel build efficiently.

Features

• Runs SwiftLint as part of the build/test. There is no need for a pre-build phase in your Xcode project anymore.
• Operates on a single Swift file at a time. This takes advantage of Bazel's powerful caching and paralleling mechanism and allows for incremental validation. You can even lint your Swift code with remote execution.
• Knows your dependency graph. The action won't run on your Swift file until you add it to your dependency tree.
• Simple integration. You just need to add a flag to your .bazelrc file and forget about it.

rules_swiftlint leverages Bazel's Validation Actions to run SwiftLint. This is special in that its outputs are always requested, regardless of the value of the --output_groups flag; and the validation is skipped when the target is depended upon as an implicit dependency, or as a tool, or is build in the exec (or the legacy host) configuration—in short, it only runs on code that goes into your app. It is, however, possible to validate your Swift tools by building or testing your tools directly.

Note that rules_swiftlint only validates, but does not format your Swift code, because source files are immutable to Bazel during a build or a test. If your workflow requires you to auto-format your Swift code, you need to run SwiftLint with bazel run:

bazel run @SwiftLint//:swiftlint -- [<SwiftLint flags>]

Installation

1. WORKSPACE setup

a. If you want to use a prebuilt binary of SwiftLint:

load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")

http_archive(
    name = "SwiftLint",
    build_file_content = """exports_files(["swiftlint"])""",
    # Update these two lines whenever you want to update SwiftLint.
    sha256 = "47078845857fa7cf8497f5861967c7ce67f91915e073fb3d3114b8b2486a9270",
    url = "https://github.com/realm/SwiftLint/releases/download/0.50.3/portable_swiftlint.zip",
)

http_archive(
    name = "com_github_thii_rules_swiftlint",
    sha256 = "<see https://github.com/thii/rules_swiftlint/releases>",
    url = "<see https://github.com/thii/rules_swiftlint/releases>",
)

load(
    "@com_github_thii_rules_swiftlint//swiftlint:repositories.bzl",
    "swiftlint_rules_dependencies",
)

swiftlint_rules_dependencies()

load(
    "@com_github_thii_rules_swiftlint//swiftlint:defs.bzl",
    "swiftlint_register_toolchains",
)

swiftlint_register_toolchains()

b. If you want to build SwiftLint from source:

• Follow instructions from https://github.com/bazelbuild/rules_apple/releases to declare rules_apple's dependencies.
• Follow instructions from https://github.com/realm/SwiftLint/releases to declare SwiftLint's dependencies.
• Add the following to your WORKSPACE file:

http_archive(
    name = "com_github_thii_rules_swiftlint",
    sha256 = "<see https://github.com/thii/rules_swiftlint/releases>",
    url = "<see https://github.com/thii/rules_swiftlint/releases>",
)

load(
    "@com_github_thii_rules_swiftlint//swiftlint:repositories.bzl",
    "swiftlint_rules_dependencies",
)

swiftlint_rules_dependencies()

load(
    "@com_github_thii_rules_swiftlint//swiftlint:defs.bzl",
    "swiftlint_register_toolchains",
)

swiftlint_register_toolchains()

2. Declare a target for your SwiftLint configuration files

Skip this step if you don't have your own SwiftLint configuration file.

Declare this in your BUILD file (e.g., in the top-level BUILD file). If you have multiple configuration files, add them all to this filegroup target.

filegroup(
    name = "swiftlint_config",
    srcs = [".swiftlint.yml"],
)

3. Add the following to your .bazelrc file

build --aspects=@com_github_thii_rules_swiftlint//swiftlint:defs.bzl%swiftlint_aspect

# This flag is only required if you have your own SwiftLint configuration file.
build --@com_github_thii_rules_swiftlint//swiftlint:config=//:swiftlint_config

Then build your target as usual. SwiftLint validation will run as part of the build and report violations as build warnings and errors.

bazel build //your:target

If you only want to run SwiftLint validation alone, add a new Bazel config for that, and explicitly request only the _validation output group:

build:swiftlint --aspects=@com_github_thii_rules_swiftlint//swiftlint:defs.bzl%swiftlint_aspect
build:swiftlint --@com_github_thii_rules_swiftlint//swiftlint:config=//:swiftlint_config
build:swiftlint --output_groups=_validation

Then you can run SwiftLint validation without building your target with:

bazel build --config=swiftlint //your:target

If you only want to build your target but skip the SwiftLint validation, you can do so by setting the --norun_validations (or --run_validations={0,false,no}) flag in your build.

bazel build --norun_validations //your:target

Examples

bazel build //examples:main

Acknowledgments

This repository uses the Bazel ruleset template from https://github.com/bazel-contrib/rules-template.