Support multiple Rust toolchain files (#20)

* Support multiple Rust toolchain files

Accept one or two toolchain directories and install the versions,
components, and targets declared by their native rustup files.

Document the breaking v2 interface and explicit default selection.

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>
Signed-off-by: Simon Davies <simongdavies@users.noreply.github.com>

* Simplify multiple toolchain setup

Use setup-rust-toolchain's source directory support for the optional
additional toolchain and update the documentation.

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>
Signed-off-by: Simon Davies <simongdavies@users.noreply.github.com>

---------

Signed-off-by: Simon Davies <simongdavies@users.noreply.github.com>
Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Author: simongdavies

README.md

@@ -9,32 +9,48 @@ jobs:
   setup:
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v7
 
-    - uses: hyperlight-dev/ci-setup-workflow@v1.0.0
-        with:
-          rust-toolchain: "1.74.0"
+    - uses: hyperlight-dev/ci-setup-workflow@v2.0.0
+      with:
+        additional-toolchain-directory: guests
 ```
 
+Check out the consumer repository before invoking the action.
+
 ## Inputs
 
 ### Parameters
 
 | Name | Description |
 | ---- | ----------- |
-| `rust-toolchain` | The rust toolchain version to use. |
+| `additional-toolchain-directory` | Optional directory containing another `rust-toolchain.toml` or `rust-toolchain` file. |
+| `just-version` | Version of Just to install; defaults to `1.41`. |
+
+The action reads `rust-toolchain.toml` or `rust-toolchain` from the repository
+root, falling back to stable when neither file exists. Set
+`additional-toolchain-directory` when another directory, such as a guest
+project, uses a different toolchain.
+
+Rustup reads the version, profile, components, and targets from each toolchain
+file. Put required extras such as `clippy`, `rustfmt`, `x86_64-unknown-none`,
+or cross-compilation targets in those files.
 
 ## Overview
 
 This action performs the following steps:
 
-- Installs the Rust tool chain at the specified version.
-- Installs additional rust components like clippy, rustfmt, ect
-- Installs Just
-- Sets up the clang toolchain on Linux machines (this should probably get moved into the hosted runner image setup...)
-- Installs the `x86_64-pc-windows-msvc` rust target for cross-compilation on Linux machines
+- Installs rustup if needed and the root toolchain (or stable by default).
+- Installs an additional toolchain when requested.
+- Installs the requested components and targets.
+- Installs Just.
+- Sets up the clang toolchain on Linux.
+- Enables the Windows Hypervisor Platform on Windows.
 - Sets up environment variables needed to build / run tests based on the machine's configuration. 
 
+Runners need Bash 5 and rustup or curl. The setup action installs rustup when
+missing and installs Bash through Homebrew on macOS.
+
 ## Code of Conduct
 
 See the [Code of Conduct](./CODE_OF_CONDUCT.md).

action.yml

@@ -4,10 +4,9 @@ name: "Hyperlight Workflow Setup"
 description: "Common setup steps for GitHub workflows in the Hyperlight project"
 
 inputs:
-  rust-toolchain:
-    description: "(Default: 1.94.0) Rust toolchain specification to install - see https://rust-lang.github.io/rustup/concepts/toolchains.html#toolchain-specification"
+  additional-toolchain-directory:
+    description: "Optional directory containing another Rust toolchain file."
     required: false
-    default: "1.94.0"
   just-version:
     description: '(Default: 1.41) Version of just to install.'
     required: false
@@ -16,12 +15,23 @@ runs:
   using: composite
   steps:
 
-    - uses: dtolnay/rust-toolchain@master
+    - name: Install Rust toolchain
+      uses: actions-rust-lang/setup-rust-toolchain@ecabd13d1c56bd1345c230e542e9144811ad706f # v2
       with:
-        toolchain: ${{ inputs.rust-toolchain }}
-        components: clippy, rustfmt
-    
-    - uses: extractions/setup-just@v4
+        cache: 'false'
+        matcher: 'false'
+        build-warnings: ''
+
+    - name: Install additional Rust toolchain
+      if: ${{ inputs.additional-toolchain-directory != '' }}
+      uses: actions-rust-lang/setup-rust-toolchain@ecabd13d1c56bd1345c230e542e9144811ad706f # v2
+      with:
+        rust-src-dir: ${{ inputs.additional-toolchain-directory }}
+        cache: 'false'
+        matcher: 'false'
+        build-warnings: ''
+
+    - uses: extractions/setup-just@53165ef7e734c5c07cb06b3c8e7b647c5aa16db3 # v4
       with:
         just-version: ${{ inputs.just-version }}
 
@@ -87,21 +97,6 @@ runs:
         fi
       shell: bash
 
-    # This is needed to build the rust guests
-    - name: Install x86_64-unknown-none target
-      if: ${{ (runner.os == 'Linux') }}
-      run: |
-        rustup target add x86_64-unknown-none
-      shell: bash
-
-    # We do this in case there is toolchain skew between repos
-    - name: Install older rust toolchain(s)
-      if: ${{ (runner.os == 'Linux') }}
-      run: |
-        rustup toolchain install 1.85.0
-        rustup toolchain install 1.86.0
-      shell: bash
-
     - name: Set up env vars (Linux)
       if: ${{ (runner.os == 'Linux') }}
       run: |
@@ -125,25 +120,6 @@ runs:
       run:  Enable-WindowsOptionalFeature -Online -FeatureName HyperVisorPlatform
       shell: pwsh
 
-    - name: Install x86_64-pc-windows-msvc target (Windows)
-      if: ${{ (runner.os == 'Windows') }}
-      run: |
-        rustup target add x86_64-pc-windows-msvc
-      shell: pwsh
-
-    - name: Install x86_64-unknown-none target (Windows)
-      if: ${{ (runner.os == 'Windows') }}
-      run: |
-        rustup target add x86_64-unknown-none
-      shell: pwsh
-
-    - name: Install older rust toolchain(s) (Windows)
-      if: ${{ (runner.os == 'Windows') }}
-      run: |
-        rustup toolchain install 1.85.0
-        rustup toolchain install 1.86.0
-      shell: pwsh
-
     - name: Set up env vars (Windows)
       if: ${{ (runner.os == 'Windows') }}
       run: |