repo: Add buf linting

initially just for unused imports

Fix cncf#45

Signed-off-by: Ryan Northey <ryan@synca.io>

bazel/repositories.bzl

@@ -6,6 +6,12 @@ def xds_api_dependencies():
         "bazel_gazelle",
         locations = REPOSITORY_LOCATIONS,
     )
+    xds_http_archive(
+        "com_github_bufbuild_buf",
+        locations = REPOSITORY_LOCATIONS,
+        build_file_content = BUF_BUILD_CONTENT,
+        tags = ["manual"],
+    )
     xds_http_archive(
         "com_envoyproxy_protoc_gen_validate",
         locations = REPOSITORY_LOCATIONS,
@@ -31,3 +37,16 @@ def xds_api_dependencies():
 # TODO(roth): Remove once all callers are updated to use the new name.
 def udpa_api_dependencies():
   xds_api_dependencies()
+
+BUF_BUILD_CONTENT = """
+package(
+    default_visibility = ["//visibility:public"],
+)
+
+filegroup(
+    name = "buf",
+    srcs = [
+        "@com_github_bufbuild_buf//:bin/buf",
+    ],
+)
+"""

bazel/repository_locations.bzl

@@ -7,6 +7,11 @@ REPOSITORY_LOCATIONS = dict(
         sha256 = "1c531376ac7e5a180e0237938a2536de0c54d93f5c278634818e0efc952dd56c",
         urls = ["https://mirror.bazel.build/github.com/bazelbuild/bazel-skylib/releases/download/1.0.3/bazel-skylib-1.0.3.tar.gz"],
     ),
+    com_github_bufbuild_buf = dict(
+        sha256 = "826ad701db09805eb425723ad3ea0c13ce7ca8353d6a1fb473399db915dafdf9",
+        strip_prefix = "buf",
+        urls = ["https://github.com/bufbuild/buf/releases/download/v1.4.0/buf-Linux-x86_64.tar.gz"],
+    ),
     com_envoyproxy_protoc_gen_validate = dict(
         sha256 = "c695fc5a2e5a1b52904cd8a58ce7a1c3a80f7f50719496fd606e551685c01101",
         strip_prefix = "protoc-gen-validate-0.6.1",

buf.lock

@@ -0,0 +1,11 @@
+# Generated by buf. DO NOT EDIT.
+version: v1
+deps:
+  - remote: buf.build
+    owner: gogo
+    repository: protobuf
+    commit: 4df00b267f944190a229ce3695781e99
+  - remote: buf.build
+    owner: googleapis
+    repository: googleapis
+    commit: d1a849b8f8304950832335723096e954

buf.yaml

@@ -0,0 +1,7 @@
+version: v1
+deps:
+    - buf.build/googleapis/googleapis:d1a849b8f8304950832335723096e954
+    - buf.build/gogo/protobuf
+lint:
+  use:
+  - IMPORT_USED

ci/check.sh

@@ -2,6 +2,9 @@
 
 set -e
 
+bazel run @com_github_bufbuild_buf//:bin/buf lint -- --path xds
+bazel run @com_github_bufbuild_buf//:bin/buf lint -- --path udpa
+
 bazel test --config=ci //...
 
 rm -rf go/xds go/udpa