feat: add Rust support in 'aspect init' (#125)

* feat: add Rust support

* chore: add rules_rust module

* Escape quotes

* Rust uses snake (or kebab) crate names, not pascal

* Create src file

* Add cargo tool

* Update rules_rust to version with upstream_tools

* Hide stderr from bazel info call

* Add instructions for running cargo

* remove src folder

* add rust ci matrix

* Add rust smoke test

* Make project in subdir to not stomp on lint

* Update ci.yaml

---------

Co-authored-by: Daniel Wagner-Hall <dawagner@gmail.com>

.github/workflows/ci.yaml

@@ -17,6 +17,7 @@ jobs:
                     - go
                     - py
                     - cpp
+                    - rust
                     - minimal
         runs-on: ubuntu-latest
         steps:
@@ -84,6 +85,28 @@ jobs:
               working-directory: "${{ steps.scaffold.outputs.dir }}"
               if: "${{ matrix.preset == 'js' }}"
 
+            - name: Rust smoke test
+              run: |
+                mkdir -p hello_world/src
+
+                cat >hello_world/BUILD.bazel <<EOF
+                load("@rules_rust//rust:defs.bzl", "rust_binary")
+
+                rust_binary(
+                    name = "hello_world",
+                    srcs = ["src/main.rs"],
+                )
+                EOF
+
+                cat >hello_world/src/main.rs <<EOF
+                fn main() { println!("Hello from Rust"); }
+                EOF
+
+                output="$(bazel run //hello_world)"
+                [[ "${output}" == "Hello from Rust" ]] || { echo >&2 "Wanted output 'Hello from Rust' but got '${output}'" ; exit 1 ; }
+              working-directory: "${{ steps.scaffold.outputs.dir }}"
+              if: "${{ matrix.preset == 'rust' }}"
+
             - run: bazel lint ...
               working-directory: "${{ steps.scaffold.outputs.dir }}"
 

scaffold.yaml

@@ -32,6 +32,7 @@ questions:
         - Go
         - Java
         - C & C++
+        - Rust
   - name: copier
     prompt:
       confirm: Setup code generation?
@@ -103,19 +104,24 @@ features:
     globs:
       - "*/.aspect/cli/go_image.star"
       - "*/tools/oci/go_image.bzl"
-
+  - value: "{{ .Computed.rust }}"
+    globs:
+      - "*/Cargo.toml"
+      - "*/tools/cargo"
+      - "*/src/main.rs"
 
 computed:
   javascript: "{{ has \"JavaScript & TypeScript\" .Scaffold.langs }}"
   python: "{{ has \"Python\" .Scaffold.langs }}"
   go: "{{ has \"Go\" .Scaffold.langs }}"
   java: "{{ has \"Java\" .Scaffold.langs }}"
   cpp: "{{ has \"C & C++\" .Scaffold.langs }}"
+  rust: "{{ has \"Rust\" .Scaffold.langs }}"
 
 presets:
   kitchen-sink:
     lint: true
-    langs: ['C & C++', 'JavaScript & TypeScript', 'Python', 'Go', 'Java']
+    langs: ['C & C++', 'JavaScript & TypeScript', 'Python', 'Go', 'Java', 'Rust']
     copier: true
     stamp: true
     protobuf: true
@@ -136,5 +142,8 @@ presets:
   cpp:
     langs: ['C & C++']
     lint: true
+  rust:
+    langs: ['Rust']
+    lint: true
   minimal:
     langs: []

{{ .ProjectSnake }}/Cargo.toml

@@ -0,0 +1,8 @@
+[package]
+name = "{{ .ProjectSnake }}"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]

{{ .ProjectSnake }}/MODULE.bazel

@@ -22,6 +22,9 @@ bazel_dep(name = "rules_python_gazelle_plugin", version = "0.36.0")
 bazel_dep(name = "aspect_rules_py", version = "0.8.1")
 bazel_dep(name = "rules_uv", version = "0.31.0")
 {{- end }}
+{{- if .Computed.rust }}
+bazel_dep(name = "rules_rust", version = "0.50.1")
+{{- end }}
 {{- if .Computed.go }}
 bazel_dep(name = "rules_go", version = "0.50.1")
 bazel_dep(name = "gazelle", version = "0.39.1")
@@ -38,6 +41,8 @@ multitool.hub(lockfile = "//tools:tools.lock.json")
 use_repo(multitool, "multitool")
 {{- if .Computed.go }}
 
+#########################
+# Go
 go_deps = use_extension("@gazelle//:extensions.bzl", "go_deps")
 go_deps.from_file(go_mod = "//:go.mod")
 
@@ -47,6 +52,8 @@ use_repo(go_deps)
 {{- end }}
 {{- if .Computed.javascript }}
 
+#########################
+# JavaScript and pnpm package manager
 pnpm = use_extension("@aspect_rules_js//npm:extensions.bzl", "pnpm")
 
 # Allows developers to run the same pnpm version that Bazel manages
@@ -71,6 +78,8 @@ use_repo(rules_ts_ext, "npm_typescript")
 {{- end}}
 {{- if .Computed.python }}
 
+#########################
+# Hermetic Python interpreter and pip dependencies
 pip = use_extension("@rules_python//python/extensions:pip.bzl", "pip")
 
 python = use_extension("@rules_python//python/extensions:python.bzl", "python")
@@ -93,9 +102,9 @@ register_toolchains(
 )
 {{- end }}
 {{- if .Computed.cpp }}
+
 #########################
 # Hermetic C++ toolchain, to relieve the dependency on a locally installed CC etc.
-
 llvm = use_extension("@toolchains_llvm//toolchain/extensions:llvm.bzl", "llvm")
 llvm.toolchain(
     # NB: llvm doesn't release for all platforms on every patch release
@@ -109,15 +118,25 @@ use_repo(llvm, "llvm_toolchain", "llvm_toolchain_llvm")
 
 register_toolchains("@llvm_toolchain//:all")
 {{- end }}
+{{- if .Computed.rust }}
+
+#########################
+# Support for Rust, see https://github.com/bazelbuild/rules_rust
+rust = use_extension("@rules_rust//rust:extensions.bzl", "rust")
+rust.toolchain(
+    edition = "2021",
+    versions = ["1.75.0"],
+)
+{{- end }}
 {{- if .Computed.java }}
+
 #########################
 # Java and other JVM languages:
 # https://github.com/bazelbuild/rules_jvm_external/blob/master/examples/bzlmod/MODULE.bazel
 # https://github.com/bazelbuild/rules_jvm_external#pinning-artifacts-and-integration-with-bazels-downloader
 
 # In the Maven support variation, the dependencies are conveniently listed here
 # in the MODULE.bazel file.
-
 maven = use_extension("@rules_jvm_external//:extensions.bzl", "maven")
 maven.install(
     artifacts = ["io.grpc:grpc-all:1.51.1"],

{{ .ProjectSnake }}/README.bazel.md

@@ -115,3 +115,25 @@ Available keys are listed in `/tools/workspace_status.sh` and may include:
 
 To request stamped build outputs, add the flag `--config=release`.
 {{ end }}
+
+{{ if .Computed.rust }}
+## Working with Cargo
+
+If you need to run `cargo` outside of Bazel, you can do so by running `./tools/cargo`, e.g.
+
+```console
+% ./tools/cargo add reqwest
+    Updating crates.io index
+      Adding reqwest v0.12.7 to dependencies.
+             Features:
+             + __tls
+             + charset
+             + default-tls
+             + h2
+             + http2
+             + macos-system-configuration
+             25 deactivated features
+    Updating crates.io index
+```
+
+{{ end }}

{{ .ProjectSnake }}/tools/_run_under_cwd.sh

@@ -9,6 +9,10 @@ case "$(basename "$0")" in
     target="//tools:copier"
     ;;
 {{- end }}
+  cargo)
+    # Being documented in https://github.com/bazelbuild/rules_rust/pull/2890
+    target="@rules_rust//tools/upstream_wrapper:cargo"
+    ;;
   go)
     # https://github.com/bazelbuild/rules_go/blob/master/docs/go/core/bzlmod.md#using-a-go-sdk
     target="@rules_go//go"
@@ -23,4 +27,4 @@ case "$(basename "$0")" in
 esac
 
 # NB: we don't use 'bazel run' because it may leave behind zombie processes under ibazel
-bazel 2>/dev/null build --build_runfile_links "$target" && BAZEL_BINDIR=. exec $(bazel info execution_root)/$(bazel 2>/dev/null cquery --output=files "$target") "$@"
+bazel 2>/dev/null build --build_runfile_links "$target" && BAZEL_BINDIR=. exec $(bazel 2>/dev/null info execution_root)/$(bazel 2>/dev/null cquery --output=files "$target") "$@"

{{ .ProjectSnake }}/tools/cargo

@@ -0,0 +1 @@
+./_run_under_cwd.sh

{{ .ProjectSnake }}/tools/format/BUILD.bazel

@@ -31,6 +31,9 @@ format_multirun(
 {{- end }}
 {{- if .Computed.python }}
     python = "@aspect_rules_lint//format:ruff",
+{{- end }}
+{{- if .Computed.rust }}
+    rust = "@rules_rust//tools/rustfmt:upstream_rustfmt",
 {{- end }}
     starlark = "@buildifier_prebuilt//:buildifier",
 )