feat: add cargo build config and prebuilt support (#91)

* add cargo build config and prebuilt support

* fix missing newline

* add missing punctation

* Update README.md

Co-authored-by: Douglas Parsons <dglsparsons@users.noreply.github.com>

---------

Co-authored-by: Douglas Parsons <dglsparsons@users.noreply.github.com>

Author: ecklf

Cargo.lock

@@ -2,9 +2,18 @@
 
 members = [
     "vercel_runtime",
-    "examples/*",
+    "examples/simple",
+    "examples/cron",
+    "examples/nextjs",
 ]
 
 exclude = [
-    "test/*",
+    "test/fixtures/01-include-files",
+    "test/fixtures/02-with-utility",
+    "test/fixtures/03-with-function",
+    "test/fixtures/04-with-parameter",
+    "test/fixtures/05-with-similar-entrypaths",
+    "test/fixtures/06-with-toolchain-override",
+    "test/fixtures/07-with-cargo-configuration",
 ]
+

Cargo.toml

@@ -99,6 +99,26 @@ This Builder supports installing dependencies defined in the `Cargo.toml` file.
 
 Furthermore, more system dependencies can be installed at build time with the presence of a shell `build.sh` file in the same directory as the entrypoint file.
 
+## Prebuilt Deployments
+
+When creating a prebuilt deployment, the build output must be for x86_64 linux. To do this, create a Cargo build configuration at `.cargo/config.toml` with the following contents:
+
+```toml
+[build]
+target = "x86_64-unknown-linux-musl"
+
+# Uncomment below to support Rust cross-compilation from macOS to Linux
+# Follow these installation instructions: https://github.com/chinedufn/cross-compile-rust-from-mac-to-linux
+# [target.x86_64-unknown-linux-musl]
+# linker = "x86_64-unknown-linux-gnu-gcc"
+```
+
+You then can build the file and trigger the deployment with the Vercel CLI.
+
+```shell
+vercel build && vercel deploy --prebuilt
+```
+
 ## Local Development
 
 With `vercel dev` and `vercel-rust`, you can develop your Rust-based lambdas on your own machine.

README.md

@@ -14,6 +14,7 @@ import {
   getCargoMetadata,
   findBinaryName,
   findCargoWorkspace,
+  findCargoBuildConfiguration,
 } from './lib/cargo';
 import {
   assertEnv,
@@ -46,7 +47,12 @@ async function buildHandler(options: BuildOptions): Promise<BuildResultV3> {
     env: rustEnv,
     cwd: path.dirname(entryPath),
   });
+
   const binaryName = findBinaryName(cargoWorkspace, entryPath);
+  const cargoBuildConfiguration = await findCargoBuildConfiguration(
+    cargoWorkspace,
+  );
+  const buildTarget = cargoBuildConfiguration?.build.target ?? '';
 
   await runUserScripts(workPath);
 
@@ -72,11 +78,13 @@ async function buildHandler(options: BuildOptions): Promise<BuildResultV3> {
 
   debug(`Building \`${binaryName}\` for \`${process.platform}\` completed`);
 
-  const { target_directory: targetDirectory } = await getCargoMetadata({
+  let { target_directory: targetDirectory } = await getCargoMetadata({
     cwd: process.cwd(),
     env: rustEnv,
   });
 
+  targetDirectory = path.join(targetDirectory, buildTarget);
+
   const bin = path.join(
     targetDirectory,
     BUILDER_DEBUG ? 'debug' : 'release',

src/index.ts

@@ -168,6 +168,35 @@ export async function findCargoWorkspace(
   };
 }
 
+interface CargoBuildConfiguration {
+  build: {
+    target?: string;
+    'target-dir'?: string;
+  };
+  target: Record<
+    string,
+    {
+      linker?: string;
+    }
+  >;
+}
+
+export async function findCargoBuildConfiguration(
+  workspace: CargoWorkspace,
+): Promise<CargoBuildConfiguration | null> {
+  const configPath = path.join(
+    path.dirname(workspace.root),
+    '.cargo/config.toml',
+  );
+
+  if (!fs.existsSync(configPath)) {
+    return null;
+  }
+
+  const config = await toml.parse.stream(fs.createReadStream(configPath));
+  return config as unknown as CargoBuildConfiguration;
+}
+
 export function findBinaryName(
   workspace: CargoWorkspace,
   entryPath: string,

src/lib/cargo.ts

@@ -102,4 +102,9 @@ describe('vercel-rust', () => {
   it('deploy 06-with-toolchain-override', async () => {
     await expect(testFixture('06-with-toolchain-override')).resolves.toBe('ok');
   });
+  it('deploy 07-with-cargo-configuration', async () => {
+    await expect(testFixture('07-with-cargo-configuration')).resolves.toBe(
+      'ok',
+    );
+  });
 });

test/fixtures.test.ts

@@ -1,7 +1,7 @@
 {
   "functions": {
     "api/**/*.rs": {
-      "runtime": "vercel-rust@4.0.0-beta.3"
+      "runtime": "vercel-dev-builder@0.0.5"
     }
   }
 }

test/fixtures/02-with-utility/vercel.json

@@ -1 +1 @@
-rustc 1.70.0-nightly (44f518058 2023-03-20)
+rustc 1.70.0-nightly (478cbb42b 2023-03-28)

test/fixtures/06-with-toolchain-override/static/toolchain.txt

@@ -0,0 +1,5 @@
+[build]
+# target = "x86_64-unknown-linux-musl"
+
+[target.x86_64-unknown-linux-musl]
+linker = "x86_64-unknown-linux-gnu-gcc"

test/fixtures/07-with-cargo-configuration/.cargo/config.toml

@@ -0,0 +1 @@
+.vercel