Reimplemented grpc-gateway as a rule (no longer genrule)

Author: pcj

bzl/base/class.bzl

@@ -1,12 +1,9 @@
 def get_generated_filename_extensions(lang, self):
 
     if not hasattr(lang, "protobuf"):
-        fail("Required struct 'protobuf' not found in lang %s" % lang.name)
-
-    if not hasattr(lang.protobuf, "file_extensions"):
-      fail("Required string_list 'file_extensions' not found in protobuf struct %s" % lang.protobuf)
+        return
 
-    exts = getattr(lang.protobuf, "file_extensions")
+    exts = getattr(lang.protobuf, "file_extensions", [])
 
     with_grpc = self.get("with_grpc", False)
     ctx = self.get("ctx", None)
@@ -24,6 +21,9 @@ def build_generated_files(lang, self):
     """Build a list of generated filenames (used by rule)"""
     exts = get_generated_filename_extensions(lang, self)
 
+    if not exts:
+        return
+
     ctx = self.get("ctx", None)
     if ctx == None:
         fail("build_generated_files can only be used in bazel context")
@@ -32,7 +32,7 @@ def build_generated_files(lang, self):
     if not protos:
         fail("Empty proto file input list.")
 
-    for srcfile in self.get("srcs", []):
+    for srcfile in protos:
         base = srcfile.basename[:-len(".proto")]
         for ext in exts:
             pbfile = ctx.new_file(base + ext)
@@ -57,8 +57,7 @@ def build_generated_filenames(lang, self):
 def build_imports(lang, self):
     """Build the list of imports"""
     ctx = self["ctx"]
-    if ctx:
-        self["imports"] = self.get("imports", []) + ctx.attr.imports
+    self["imports"] = self.get("imports", []) + ctx.attr.imports
 
 def build_plugin_out(name, key, lang, self):
     #print("build_plugin_out(%s, %s)" % (name, key))
@@ -140,7 +139,6 @@ def build_protoc_command(lang, self):
 
 def build_inputs(lang, self):
     """Build a list of inputs to the ctx.action protoc"""
-    #self["inputs"] += self["srcs"]
     self["requires"] += self["srcs"]
 
 

bzl/build_file/com_github_grpc_ecosystem_grpc_gateway.BUILD

@@ -19,7 +19,7 @@ go_library(
 )
 
 filegroup(
-    name = "googleapis",
+    name = "googleapi_protos",
     srcs = glob([
         "third_party/googleapis/google/api/*.proto",
     ]),

bzl/classes.bzl

@@ -8,12 +8,12 @@ load("//bzl:javanano/class.bzl", JAVANANO = "CLASS")
 load("//bzl:grpc_gateway/class.bzl", GATEWAY = "CLASS")
 
 CLASSES = {
-    "base": BASE,
-    "cpp": CPP,
-    "gateway": GATEWAY,
-    "java": JAVA,
-    "javanano": JAVANANO,
-    "go": GO,
-    "py": PYTHON,
-    "ruby": RUBY,
+    BASE.name: BASE,
+    CPP.name: CPP,
+    GATEWAY.name: GATEWAY,
+    JAVA.name: JAVA,
+    JAVANANO.name: JAVANANO,
+    GO.name: GO,
+    PYTHON.name: PYTHON,
+    RUBY.name: RUBY,
 }

bzl/cpp/README.md

@@ -71,7 +71,7 @@ cc_library(
   srcs = ['MyApp.cpp'],
   deps = [
     ":protolib"
-  ] + CC.grpc.compile_deps,
+  ] + CPP.grpc.compile_deps,
 )
 ```
 

bzl/cpp/rules.bzl

@@ -2,7 +2,7 @@ load("//bzl:protoc.bzl", "implement", "EXECUTABLE")
 load("//bzl:util.bzl", "invoke")
 load("//bzl:cpp/class.bzl", CPP = "CLASS")
 
-cc_proto_compile = implement(["cpp"])
+cc_proto_compile = implement([CPP.name])
 
 def cc_proto_library(
     name,

bzl/go/class.bzl

@@ -19,11 +19,20 @@ def implement_compile_attributes(lang, self):
         cfg = HOST_CFG,
     )
 
+    attrs["go_import_map"] = attr.string_dict()
+
 
 def build_protobuf_out(lang, self):
     """Override behavior to add a plugin option before building the --go_out option"""
     if self.get("with_grpc", False):
         self["protobuf_plugin_options"] = self.get("protobuf_plugin_options", []) + ["plugins=grpc"]
+
+    ctx = self["ctx"]
+    if ctx.attr.verbose > 1:
+        print("go_import_map: %s" % ctx.attr.go_import_map)
+    for k, v in ctx.attr.go_import_map.items():
+        self["protobuf_plugin_options"] += ["M%s=%s" % (k, v)]
+
     invokesuper("build_protobuf_out", lang, self)
 
 
@@ -37,8 +46,6 @@ def build_imports(lang, self):
     invokesuper("build_imports", lang, self)
 
     ctx = self["ctx"]
-    if not ctx:
-        fail("Bazel context is required for build_imports")
 
     go_prefix = ctx.attr.go_prefix.go_prefix
 

bzl/go/rules.bzl

@@ -2,7 +2,7 @@ load("//bzl:protoc.bzl", "implement", "EXECUTABLE")
 load("//bzl:go/class.bzl", GO = "CLASS")
 load("@io_bazel_rules_go//go:def.bzl", "go_library")
 
-go_proto_compile = implement(["go"])
+go_proto_compile = implement([GO.name])
 
 def go_proto_library(
     name,

bzl/grpc_gateway/class.bzl

@@ -2,48 +2,85 @@ load("//bzl:base/class.bzl", BASE = "CLASS", "build_plugin_out")
 load("//bzl:go/class.bzl", GO = "CLASS")
 load("//bzl:util.bzl", "invokesuper")
 
+# https://github.com/bazelbuild/bazel/blame/master/src/main/java/com/google/devtools/build/lib/packages/BuildType.java#L227
+# NPE at BuildType.java:227 when str() is used to wrap Label i.e. attr.label_list(default = [str(Label("...")])
+
+def implement_compile_attributes(lang, self):
+    """Override attributes for the X_proto_compile rule"""
+    GO.implement_compile_attributes(lang, self)
+    #invokesuper("implement_compile_attributes", lang, self)
+
+    attrs = self["attrs"]
+
+    attrs["_googleapi_protos"] = attr.label(
+        default = Label(
+            "@com_github_grpc_ecosystem_grpc_gateway//:googleapi_protos",
+        ),
+    )
+
+    attrs["logtostderr"] = attr.bool(default = True)
+    attrs["alsologtostderr"] = attr.bool()
+    attrs["stderrthreshold"] = attr.int()
+    attrs["log_backtrace_at"] = attr.int()
+    attrs["log_dir"] = attr.string()
+    attrs["log_level"] = attr.int()
+    # TODO:-vmodule value: what does this mean?
+
+    attrs["import_prefix"] = attr.string()
+
 
 def build_imports(lang, self):
     invokesuper("build_imports", lang, self)
+
     self["imports"] += [
-        "external/com_github_grpc_ecosystem_grpc_gateway/third_party/googleapis",
-        "external/com_github_google_protobuf/src",
-        ".",
+        "external/com_github_grpc_ecosystem_grpc_gateway/third_party/googleapis/",
+        "external/com_github_google_protobuf/src/",
     ]
 
 def build_inputs(lang, self):
     invokesuper("build_inputs", lang, self)
-    self["requires"] += [
-        "@com_github_grpc_ecosystem_grpc_gateway/third_party/googleapis",
-    ]
+    ctx = self["ctx"]
+    self["requires"] += list(ctx.attr._googleapi_protos.files)
+
+
+def build_protobuf_out(lang, self):
+    # Standard protobuf outputs are implemented by the GO.class, so
+    # there is no additional work to be done here.
+    pass
+
 
 def build_grpc_out(lang, self):
+    ctx = self["ctx"]
+    outdir = self["outdir"]
     opts = self.get("gateway_plugin_options", [])
-    opts += ["logtostderr=true"]
-    outdir = self["gendir"]
-    if opts:
-        outdir = ",".join(opts) + ":" + outdir
-    self["args"] += ["--grpc-gateway_out=%s" % (outdir)]
+
+    if ctx.attr.logtostderr:
+        opts += ["logtostderr=true"]
+    if ctx.attr.alsologtostderr:
+        opts += ["alsologtostderr=true"]
+    if ctx.attr.log_backtrace_at:
+        opts += ["log_backtrace_at=%s" % ctx.attr.log_backtrace_at]
+    if ctx.attr.stderrthreshold:
+        opts += ["stderrthreshold=%s" % ctx.attr.stderrthreshold]
+    if ctx.attr.log_dir:
+        opts += ["log_dir=%s" % ctx.attr.log_dir]
+    if ctx.attr.log_level:
+        opts += ["v=%s" % ctx.attr.log_level]
+    if ctx.attr.import_prefix:
+        opts += ["import_prefix=%s" % ctx.attr.import_prefix]
+
+    params = ",".join(opts) + ":" + outdir
+
+    self["args"] += ["--grpc-gateway_out=%s" % params]
 
 
 CLASS = struct(
         parent = BASE,
-        name = "go", # Left as "go" to implement gen_go and hence --protoc-gen-go=...
-        short_name = "gateway",
-
-        protobuf = struct(
-            name = GO.protobuf.name,
-            file_extensions = GO.protobuf.file_extensions,
-            executable = GO.protobuf.executable,
-            tools = [
-                "@com_github_grpc_ecosystem_grpc_gateway//:googleapis",
-            ],
-            default_options = [
-                "Mgoogle/api/annotations.proto=github.com/grpc-ecosystem/grpc-gateway/third_party/googleapis/google/api",
-            ],
-            requires = GO.protobuf.requires,
-            compile_deps = GO.protobuf.compile_deps,
-        ),
+        name = "gateway",
+
+        default_go_import_map = {
+            "google/api/annotations.proto": "github.com/grpc-ecosystem/grpc-gateway/third_party/googleapis/google/api"
+        },
 
         grpc = struct(
             name = 'protoc-gen-grpc-gateway',
@@ -62,8 +99,11 @@ CLASS = struct(
             ],
         ),
 
-        build_protobuf_out = GO.build_protobuf_out,
+        build_protobuf_out = build_protobuf_out,
+        implement_compile_attributes = implement_compile_attributes,
+
         build_grpc_out = build_grpc_out,
         build_imports = build_imports,
         build_inputs = build_inputs,
+
 )