Building gRPC Gateway Binary Using Bazel using 'grpc-gateway'

BUILD

load("@io_bazel_rules_go//go:def.bzl", "go_library", "go_binary")
load("@io_bazel_rules_go//proto:def.bzl", "go_proto_library")

##########
# Common #
##########
proto_library(
    name = "project_proto",
    srcs = [
        "project.proto",
    ],
    deps = [
      "@com_github_googleapis_googleapis//google/api:annotations_proto",
    ],
    visibility = ["//visibility:public"],
)

######
# Go #
######
go_proto_library(
    name = "project_go_proto",
    compilers = [
        "@io_bazel_rules_go//proto:go_grpc",
        "@com_github_grpc_ecosystem_grpc_gateway//protoc-gen-grpc-gateway:go_gen_grpc_gateway",
    ],
    importpath = "github.com/user/project",
    proto = ":project_proto",
    deps = [
      "@com_github_googleapis_googleapis//google/api:annotations_go_proto",
      "@com_github_golang_protobuf//descriptor:go_default_library_gen",
    ],
)

go_binary(
    name = "project_grpc_gateway",
    srcs = [
        "main.go",
    ],
    visibility = ["//visibility:public"],
    deps = [
        "@com_github_grpc_ecosystem_grpc_gateway//runtime:go_default_library",
        ":project_go_proto",
    ],
)

WORKSPACE

http_archive(
    name = "io_bazel_rules_go",
    urls = [
        "https://storage.googleapis.com/bazel-mirror/github.com/bazelbuild/rules_go/releases/download/0.19.3/rules_go-0.19.3.tar.gz",
        "https://github.com/bazelbuild/rules_go/releases/download/0.19.3/rules_go-0.19.3.tar.gz",
    ],
    sha256 = "313f2c7a23fecc33023563f082f381a32b9b7254f727a7dd2d6380ccc6dfe09b",
)

grpc_gateway_version = "9d0c596203d5ceb50d4071f4f67020873e60d17a" # Change it to the Commit you would like to work with.

http_archive(
    name = "com_github_grpc_ecosystem_grpc_gateway",
    url = "https://github.com/grpc-ecosystem/grpc-gateway/archive/%s.tar.gz" % grpc_gateway_version,
    strip_prefix = "grpc-gateway-%s" % grpc_gateway_version,
)

load("@io_bazel_rules_go//go:deps.bzl", "go_rules_dependencies", "go_register_toolchains")

go_rules_dependencies()

go_register_toolchains()

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

load("@com_github_grpc_ecosystem_grpc_gateway//:repositories.bzl", "go_repositories")

go_repositories()

As someone who doesn't know the first thing about Go but was hoping to get a gateway running for services written in another language, what would the main.go look like?

There's a minimal example here:
https://grpc-ecosystem.github.io/grpc-gateway/docs/tutorials/creating_main.go/

I suggest checking all the "Tutorial" section, as this will give the main.go file more context. Also note this gist is a bit out-dated. The BUILD file is probably the same, but the WORKSPACE can be update as gRPC Gateway now running v2.