Use grpc_build_system.bzl in other projects

Added //external to grpc deps in case where grpc_build_system.bzl is
imported in a project that is using grpc as a dependency.

1 files changed, 18 insertions, 3 deletions

diff --git a/bazel/cc_grpc_library.bzl b/bazel/cc_grpc_library.bzl
index 9020eacb74..94874fe937 100644
--- a/bazel/cc_grpc_library.bzl
+++ b/bazel/cc_grpc_library.bzl
@@ -2,7 +2,7 @@
 
 load("//:bazel/generate_cc.bzl", "generate_cc")
 
-def cc_grpc_library(name, srcs, deps, proto_only, **kwargs):
+def cc_grpc_library(name, srcs, deps, proto_only, use_external, **kwargs):
   """Generates C++ grpc classes from a .proto file.
 
   Assumes the generated classes will be used in cc_api_version = 2.
@@ -12,6 +12,8 @@ def cc_grpc_library(name, srcs, deps, proto_only, **kwargs):
       srcs: a single proto_library, which wraps the .proto files with services.
       deps: a list of C++ proto_library (or cc_proto_library) which provides
         the compiled code of any message that the services depend on.
+      use_external: When True the grpc deps are prefixed with //external. This
+        allows grpc to be used as a dependency in other bazel projects.
       **kwargs: rest of arguments, e.g., compatible_with and visibility.
   """
   if len(srcs) > 1:
@@ -37,18 +39,31 @@ def cc_grpc_library(name, srcs, deps, proto_only, **kwargs):
   )
 
   if not proto_only:
+    if use_external:
+      # when this file is used by non-grpc projects
+      plugin = "//external:grpc_cpp_plugin"
+    else:
+      plugin = "//:grpc_cpp_plugin"
+
     generate_cc(
         name = codegen_grpc_target,
         srcs = [proto_target],
-        plugin = "//:grpc_cpp_plugin",
+        plugin = plugin,
         **kwargs
     )
 
+    if use_external:
+      # when this file is used by non-grpc projects
+      grpc_deps = ["//external:grpc++", "//external:grpc++_codegen_proto",
+                   "//external:protobuf"]
+    else:
+      grpc_deps = ["//:grpc++", "//:grpc++_codegen_proto", "//external:protobuf"]
+
     native.cc_library(
         name = name,
         srcs = [":" + codegen_grpc_target, ":" + codegen_target],
         hdrs = [":" + codegen_grpc_target, ":" + codegen_target],
-        deps = deps + ["//:grpc++", "//:grpc++_codegen_proto", "//external:protobuf"],
+        deps = deps + grpc_deps,
         **kwargs
     )
   else: