Build micro_rpc for bare metal with Bazel (second edition).

BUG: 340185847
Change-Id: I63093f971b4dda1e818926f0338ae3727ad54e3a

Cargo.bazel.lock

@@ -744,6 +744,7 @@ dependencies = [
  "procfs",
  "prost",
  "prost-build",
+ "prost-derive",
  "prost-types",
  "rand_core",
  "regex",

Cargo_no_std.bazel.lock

@@ -41,6 +41,7 @@ dependencies = [
  "bytes",
  "getrandom",
  "log",
+ "prost",
  "x86_64",
 ]
 
@@ -67,6 +68,15 @@ version = "0.4.21"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "90ed8c1e510134f979dbc4f070f87d4313098b704861a105fe34231c70a3901c"
 
+[[package]]
+name = "prost"
+version = "0.12.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "deb1435c188b76130da55f17a466d252ff7b1418b2ad3e037d127b94e3411f29"
+dependencies = [
+ "bytes",
+]
+
 [[package]]
 name = "rustversion"
 version = "1.0.16"

WORKSPACE

@@ -564,6 +564,9 @@ crates_repository(
             features = ["prost-derive"],
             version = "*",
         ),
+        "prost-derive": crate.spec(
+            version = "*",
+        ),
         "prost-build": crate.spec(
             version = "*",
         ),
@@ -703,6 +706,12 @@ crates_repository(
             features = [],
             version = "*",
         ),
+        "prost": crate.spec(
+            default_features = False,
+            # No derive feature - it requires std and will make other crates
+            # in this index, like bytes, require std.
+            version = "*",
+        ),
         "x86_64": crate.spec(version = "*"),
     },
     supported_platform_triples = [

cargo-bazel-lock.json

@@ -1,5 +1,5 @@
 {
-  "checksum": "cf72206d8060287b076fedaeccc63131ecb47e453b310a56cb0a4c11f1900455",
+  "checksum": "1230c1a0283e3fd0d98539343f1a0dc7140874471b93228f8fc2bcebfe50f4d5",
   "crates": {
     "acpi 5.0.0": {
       "name": "acpi",
@@ -4588,6 +4588,10 @@
             {
               "id": "async-trait 0.1.79",
               "target": "async_trait"
+            },
+            {
+              "id": "prost-derive 0.12.4",
+              "target": "prost_derive"
             }
           ],
           "selects": {}
@@ -19350,6 +19354,7 @@
     "procfs 0.16.0",
     "prost 0.12.4",
     "prost-build 0.12.3",
+    "prost-derive 0.12.4",
     "prost-types 0.12.3",
     "rand_core 0.6.4",
     "regex 1.10.4",

cargo-no-std-bazel-lock.json

@@ -1,5 +1,5 @@
 {
-  "checksum": "7d35e77527edbd7a0a9f635fb185d7c95cd49f7877c7f4a65b183212d648d18b",
+  "checksum": "631d10644e387894ecdde4db0556fe725d97f7c5bd599465b375cdeb5dee84fd",
   "crates": {
     "anyhow 1.0.83": {
       "name": "anyhow",
@@ -267,6 +267,10 @@
               "id": "log 0.4.21",
               "target": "log"
             },
+            {
+              "id": "prost 0.12.6",
+              "target": "prost"
+            },
             {
               "id": "x86_64 0.15.1",
               "target": "x86_64"
@@ -452,6 +456,53 @@
       ],
       "license_file": "LICENSE-APACHE"
     },
+    "prost 0.12.6": {
+      "name": "prost",
+      "version": "0.12.6",
+      "package_url": "https://github.com/tokio-rs/prost",
+      "repository": {
+        "Http": {
+          "url": "https://static.crates.io/crates/prost/0.12.6/download",
+          "sha256": "deb1435c188b76130da55f17a466d252ff7b1418b2ad3e037d127b94e3411f29"
+        }
+      },
+      "targets": [
+        {
+          "Library": {
+            "crate_name": "prost",
+            "crate_root": "src/lib.rs",
+            "srcs": {
+              "allow_empty": false,
+              "include": [
+                "**/*.rs"
+              ]
+            }
+          }
+        }
+      ],
+      "library_target_name": "prost",
+      "common_attrs": {
+        "compile_data_glob": [
+          "**"
+        ],
+        "deps": {
+          "common": [
+            {
+              "id": "bytes 1.6.0",
+              "target": "bytes"
+            }
+          ],
+          "selects": {}
+        },
+        "edition": "2021",
+        "version": "0.12.6"
+      },
+      "license": "Apache-2.0",
+      "license_ids": [
+        "Apache-2.0"
+      ],
+      "license_file": null
+    },
     "rustversion 1.0.16": {
       "name": "rustversion",
       "version": "1.0.16",
@@ -695,6 +746,7 @@
     "bytes 1.6.0",
     "getrandom 0.2.15",
     "log 0.4.21",
+    "prost 0.12.6",
     "x86_64 0.15.1"
   ],
   "direct_dev_deps": []

justfile

@@ -172,7 +172,7 @@ kokoro_run_tests: all_ensure_no_std
 clang-tidy:
     bazel build $BAZEL_CONFIG_FLAG --config=clang-tidy //cc/...
 
-bare_metal_crates := "//oak_linux_boot_params //oak_channel //oak_core //oak_virtio //third_party/rust-hypervisor-firmware-virtio"
+bare_metal_crates := "//oak_linux_boot_params //oak_channel //oak_core //oak_virtio //third_party/rust-hypervisor-firmware-virtio //micro_rpc"
 
 bazel-ci:
     bazel build --config=unsafe-fast-presubmit -- @jemalloc //...:all

micro_rpc/BUILD

@@ -27,11 +27,24 @@ rust_library(
     srcs = glob(["src/**"]),
     proc_macro_deps = [
         "@oak_crates_index//:async-trait",
+        "@oak_crates_index//:prost-derive",
     ],
     deps = [
         ":build",
-        "@oak_crates_index//:prost",
-    ],
+    ] + select({
+        "@platforms//os:none": [
+            "@oak_no_std_crates_index//:prost",
+        ],
+        "//conditions:default": [
+            # When not building for bare metal, use the crate with std. Crates that require std
+            # and that also require prost won't work with @oak_no_std_crates_index//:prost. For
+            # example, oak_containers_orchestrator uses tonic which uses both prost and std.
+            # Both oak_containers_orchestrator and tonic need to see the same prost symbols.
+            # It doesn't work if one sees "@oak_no_std_crates_index//:prost" and the other
+            # sees "@oak_crates_index//:prost".
+            "@oak_crates_index//:prost",
+        ],
+    }),
 )
 
 cargo_build_script(
@@ -42,8 +55,11 @@ cargo_build_script(
     build_script_env = {
         "PROTOC": "$(execpath @com_google_protobuf//:protoc)",
     },
+    crate_features = ["bazel"],  # See b/340185847 and fix_prost_derives function doc.
     data = [
         "//proto/micro_rpc:messages_proto",
+    ],
+    tools = [
         "@com_google_protobuf//:protoc",
     ],
     deps = [

micro_rpc/build.rs

@@ -14,10 +14,52 @@
 // limitations under the License.
 //
 
-fn main() {
+#[cfg(feature = "bazel")]
+use std::fs;
+
+fn main() -> Result<(), Box<dyn std::error::Error>> {
     micro_rpc_build::compile(
         &["../proto/micro_rpc/messages.proto"],
         &["../proto"],
         Default::default(),
     );
+
+    #[cfg(feature = "bazel")]
+    fix_prost_derives()?;
+
+    Ok(())
+}
+
+#[cfg(feature = "bazel")]
+/// Replaces refs to prost with prost_derive. See b/340185847.
+/// Only to be called from build scripts of crates that generate prost code.
+/// Only to be called when building with Bazel.
+/// The issue that this fixes is that prost with "derive" feature uses
+/// "prost-derive", which requires std. In Cargo, that works OK as the
+/// feature "std" isn't propagated to deps of crates that don't use them,
+/// but Bazel's can't handle that. With Bazel, if we bring prost-derive
+/// into the index, it'll make deps like `bytes` also use the "std" feature.
+/// Take into account that in Cargo, features of dependencies are declared in
+/// the "depending" crate, that is, they belong to the dependency arc, while
+/// in Bazel, one crate is brought into an index with a fixed set of features.
+/// To solve this, and to be able to build for bare metal from Bazel, we
+/// import prost without derive to oak_no_std_crates_index, use prost-derive
+/// derive macro directly, but we need to change the crate name, as we no
+/// longer have prost re-exporting the derive macros.
+pub fn fix_prost_derives() -> Result<(), Box<dyn std::error::Error>> {
+    // let out_dir_path = std::path::PathBuf::from(std::env::var("OUT_DIR"))?;
+
+    let out_dir = std::env::var("OUT_DIR")?;
+    for entry in fs::read_dir(&out_dir)? {
+        let file_path = entry?.path();
+        let contents = fs::read_to_string(&file_path)?;
+
+        let updated = contents.replace("::prost::Message", "::prost_derive::Message");
+        let updated = updated.replace("::prost::Oneof", "::prost_derive::Oneof");
+        let updated = updated.replace("::prost::Enumeration", "::prost_derive::Enumeration");
+
+        fs::write(&file_path, updated)?;
+    }
+
+    Ok(())
 }

third_party/rust-hypervisor-firmware-virtio/BUILD

@@ -25,8 +25,8 @@ rust_library(
     srcs = glob(["src/**"]),
     deps = [
         "@oak_crates_index//:atomic_refcell",
-        "@oak_no_std_crates_index//:log",
         "@oak_no_std_crates_index//:bitflags",
+        "@oak_no_std_crates_index//:log",
         "@oak_no_std_crates_index//:x86_64",
     ],
 )