WIP: try to use aspects, inspired by protoxform

Signed-off-by: norbjd <[email protected]>

tools/protojsonschema_with_aspects/BUILD

@@ -0,0 +1,13 @@
+load("//tools/protojsonschema_with_aspects:protojsonschema.bzl", "protojsonschema_rule")
+
+licenses(["notice"])  # Apache 2
+
+protojsonschema_rule(
+    name = "api_protojsonschema",
+    visibility = ["//visibility:public"],
+    deps = [
+        #"@envoy_api//versioning:active_protos",
+        #"@envoy_api//versioning:frozen_protos",
+        "@envoy_api//envoy/annotations:pkg", # just for testing
+    ],
+)

tools/protojsonschema_with_aspects/protojsonschema.bzl

@@ -0,0 +1,121 @@
+load("@bazel_skylib//rules:common_settings.bzl", "BuildSettingInfo")
+load("@rules_proto//proto:defs.bzl", "ProtoInfo")
+
+def create_protojsonschema_aspect(aspect_impl):
+    _attrs = {
+        "_protoc": attr.label(
+            default = Label("@com_google_protobuf//:protoc"),
+            executable = True,
+            cfg = "exec",
+        ),
+        "_protoc_plugin": attr.label(
+            default = Label("@com_github_chrusty_protoc_gen_jsonschema//cmd/protoc-gen-jsonschema:protoc-gen-jsonschema"),
+            executable = True,
+            cfg = "exec",
+        ),
+    }
+
+    return aspect(
+        attr_aspects = ["deps"],
+        attrs = _attrs,
+        implementation = aspect_impl,
+    )
+
+# Borrowed from https://github.com/grpc/grpc-java/blob/v1.24.1/java_grpc_library.bzl#L61
+def _path_ignoring_repository(f):
+    virtual_imports = "/_virtual_imports/"
+    if virtual_imports in f.path:
+        return f.path.split(virtual_imports)[1].split("/", 1)[1]
+    elif len(f.owner.workspace_root) == 0:
+        # |f| is in the main repository
+        return f.short_path
+    else:
+        # If |f| is a generated file, it will have "bazel-out/*/genfiles" prefix
+        # before "external/workspace", so we need to add the starting index of "external/workspace"
+        return f.path[f.path.find(f.owner.workspace_root) + len(f.owner.workspace_root) + 1:]
+
+def _protojsonschema_impl(target, ctx):
+    output_group = "proto"
+
+    transitive_outputs = depset(transitive = [dep.output_groups[output_group] for dep in ctx.rule.attr.deps])
+
+    if ProtoInfo not in target:
+        return [OutputGroupInfo(**{output_group: transitive_outputs})]
+
+    proto_sources = [
+        f
+        for f in target[ProtoInfo].direct_sources
+        if (f.path.startswith("external/envoy_api") or
+            f.path.startswith("tools/testdata/protoxform/envoy") or
+            f.path.startswith("external/com_github_cncf_udpa/xds"))
+    ]
+
+    if not proto_sources:
+        return [OutputGroupInfo(**{output_group: transitive_outputs})]
+
+    import_paths = []
+    for f in target[ProtoInfo].transitive_sources.to_list():
+        import_paths.append("{}={}".format(_path_ignoring_repository(f), f.path))
+
+    # TODO: problem here => not 1 output per file and name can't be inferred
+    # e.g. resource.proto => ResourceAnnotation.json
+    outputs = []
+    for f in proto_sources:
+        f_path_split = f.path.split("/")
+        output_file = ctx.label.name + "/" + f_path_split[len(f_path_split)-1] + ".json"
+        outputs.append(ctx.actions.declare_file(output_file))
+
+    # Create the protoc command-line args.
+    inputs = [target[ProtoInfo].transitive_sources]
+
+    ctx_path = ctx.label.package + "/" + ctx.label.name
+    output_path = outputs[0].root.path + "/" + outputs[0].owner.workspace_root + "/" + ctx_path
+
+    args = ctx.actions.args()
+    args.add(ctx.label.workspace_root, format = "-I./%s")
+    args.add_all(import_paths, format_each = "-I%s")
+    args.add(ctx.executable._protoc_plugin, format = "--plugin=protoc-gen-api_proto_plugin=%s")
+    args.add(output_path, format = "--api_proto_plugin_out=%s")
+    args.add_all(target[ProtoInfo].direct_sources)
+
+    ctx.actions.run(
+        inputs = depset(transitive = inputs),
+        outputs = outputs,
+        executable = ctx.executable._protoc,
+        arguments = [args],
+        tools = [ctx.executable._protoc_plugin],
+    )
+
+    transitive_outputs = depset(outputs, transitive = [transitive_outputs])
+    return [OutputGroupInfo(**{output_group: transitive_outputs})]
+
+protojsonschema_aspect = create_protojsonschema_aspect(_protojsonschema_impl)
+
+def _protojsonschema_rule_impl(ctx):
+    deps = []
+    for dep in ctx.attr.deps:
+        for path in dep[OutputGroupInfo].proto.to_list():
+            envoy_api = (
+                path.short_path.startswith("../envoy_api") or
+                path.short_path.startswith("../com_github_cncf_udpa") or
+                path.short_path.startswith("tools/testdata")
+            )
+            if envoy_api:
+                deps.append(path)
+
+    return [
+        DefaultInfo(
+            files = depset(
+                transitive = [
+                    depset(deps),
+                ],
+            ),
+        ),
+    ]
+
+protojsonschema_rule = rule(
+    implementation = _protojsonschema_rule_impl,
+    attrs = {
+        "deps": attr.label_list(aspects = [protojsonschema_aspect]),
+    },
+)