feat: set default Rust toolchain (#715)

* feat: use RUSTUP_TOOLCHAIN env var

* refactor: set default toolchain

Co-authored-by: kodiakhq[bot] <49736102+kodiakhq[bot]@users.noreply.github.com>

src/runtimes/rust/builder.js

@@ -18,7 +18,7 @@ const build = async ({ config, name, srcDir }) => {
   const functionName = basename(srcDir)
 
   try {
-    await installBuildTarget()
+    await installToolchainOnce()
   } catch (error) {
     error.customErrorInfo = { type: 'functionsBundling', location: { functionName, runtime: RUNTIME_RUST } }
 
@@ -98,17 +98,22 @@ const getTargetDirectory = async ({ config, name }) => {
   return path
 }
 
-let buildTargetInstallation
+let toolchainInstallation
 
-// Installs the build target defined in `BUILD_TARGET`. The Promise is saved to
-// `buildTargetInstallation` so that we run the command just once for multiple
-// Rust functions.
-const installBuildTarget = () => {
-  if (buildTargetInstallation === undefined) {
-    buildTargetInstallation = runCommand('rustup', ['target', 'add', BUILD_TARGET])
+// Sets the default toolchain and installs the build target defined in
+// `BUILD_TARGET`. The Promise is saved to `toolchainInstallation`, so
+// that we run the command just once for multiple Rust functions.
+const installToolchain = async () => {
+  await runCommand('rustup', ['default', 'stable'])
+  await runCommand('rustup', ['target', 'add', BUILD_TARGET])
+}
+
+const installToolchainOnce = () => {
+  if (toolchainInstallation === undefined) {
+    toolchainInstallation = installToolchain()
   }
 
-  return buildTargetInstallation
+  return toolchainInstallation
 }
 
 module.exports = { build }

tests/main.js

@@ -1985,26 +1985,32 @@ test.serial('Builds Rust functions from source if the `buildRustSource` feature
   })
 
   t.is(files.length, 2)
-  t.is(shellUtilsStub.callCount, 3)
+  // eslint-disable-next-line no-magic-numbers
+  t.is(shellUtilsStub.callCount, 4)
 
   const { args: call1 } = shellUtilsStub.getCall(0)
   const { args: call2 } = shellUtilsStub.getCall(1)
-  const { args: call3 } = shellUtilsStub.getCall(1)
+  const { args: call3 } = shellUtilsStub.getCall(2)
+  const { args: call4 } = shellUtilsStub.getCall(3)
 
   t.is(call1[0], 'rustup')
-  t.is(call1[1][0], 'target')
-  t.is(call1[1][1], 'add')
-  t.is(call1[1][2], 'x86_64-unknown-linux-musl')
+  t.is(call1[1][0], 'default')
+  t.is(call1[1][1], 'stable')
 
-  t.is(call2[0], 'cargo')
-  t.is(call2[1][0], 'build')
-  t.is(call2[1][1], '--target')
+  t.is(call2[0], 'rustup')
+  t.is(call2[1][0], 'target')
+  t.is(call2[1][1], 'add')
   t.is(call2[1][2], 'x86_64-unknown-linux-musl')
 
-  t.is(call2[0], call3[0])
-  t.is(call2[1][0], call3[1][0])
-  t.is(call2[1][1], call3[1][1])
-  t.is(call2[1][2], call3[1][2])
+  t.is(call3[0], 'cargo')
+  t.is(call3[1][0], 'build')
+  t.is(call3[1][1], '--target')
+  t.is(call3[1][2], 'x86_64-unknown-linux-musl')
+
+  t.is(call4[0], call3[0])
+  t.is(call4[1][0], call3[1][0])
+  t.is(call4[1][1], call3[1][1])
+  t.is(call4[1][2], call3[1][2])
 
   t.is(files[0].mainFile, join(FIXTURES_DIR, fixtureName, 'rust-func-1', 'src', 'main.rs'))
   t.is(files[0].name, 'rust-func-1')