Speed up rust crate installs in workflow by using cargo-binstall (#2915)

When cargo xtask install-tools --binstall is used, precompiled binaries
are fetched if available.
Triggers a regular (compilation) install if binary releases do not
exist.

This is now configured to be used by the CI to speed up the build and
deploy workflows where possible.

Currently binary packages exist for:
- mdbook
- mdbook-pandoc

.github/workflows/install-mdbook/action.yml

@@ -5,8 +5,11 @@ description: Install mdbook with the dependencies we need.
 runs:
   using: composite
   steps:
+    - name: Ensure cargo-binstall is installed
+      uses: cargo-bins/cargo-binstall@main
+
     - name: Install mdbook
-      run: cargo xtask install-tools
+      run: cargo xtask install-tools --binstall
       shell: bash
 
     - name: Install dependencies for mdbook-pandoc

xtask/src/main.rs

@@ -42,7 +42,11 @@ struct Cli {
 #[derive(Subcommand)]
 enum Task {
     /// Installs the tools the project depends on.
-    InstallTools,
+    InstallTools {
+        /// Use cargo-binstall for faster installation.
+        #[arg(long)]
+        binstall: bool,
+    },
     /// Runs the web driver tests in the tests directory.
     WebTests {
         /// Optional 'book html' directory - if set, will also refresh the list
@@ -79,7 +83,7 @@ enum Task {
 fn execute_task() -> Result<()> {
     let cli = Cli::parse();
     match cli.task {
-        Task::InstallTools => install_tools(),
+        Task::InstallTools { binstall } => install_tools(binstall),
         Task::WebTests { dir } => run_web_tests(dir),
         Task::RustTests => run_rust_tests(),
         Task::Serve { language, output } => start_web_server(language, output),
@@ -105,9 +109,13 @@ fn run_command(cmd: &mut Command) -> Result<()> {
     Ok(())
 }
 
-fn install_tools() -> Result<()> {
+fn install_tools(binstall: bool) -> Result<()> {
     println!("Installing project tools...");
 
+    let cargo = env!("CARGO");
+
+    let install_command = if binstall { "binstall" } else { "install" };
+
     const PINNED_NIGHTLY: &str = "nightly-2025-09-01";
 
     // Install rustup components
@@ -121,7 +129,6 @@ fn install_tools() -> Result<()> {
         run_command(&mut cmd)?;
     }
 
-    let cargo = env!("CARGO");
     // The --locked flag is important for reproducible builds.
     let tools = [
         ("mdbook", "0.4.52"),
@@ -134,12 +141,13 @@ fn install_tools() -> Result<()> {
 
     for (tool, version) in tools {
         let mut cmd = Command::new(cargo);
-        cmd.args(["install", tool, "--version", version, "--locked"]);
+        cmd.args([install_command, tool, "--version", version, "--locked"]);
         run_command(&mut cmd)?;
     }
 
     // Install local tools from the workspace.
     let workspace_dir = Path::new(env!("CARGO_WORKSPACE_DIR"));
+    // cargo-binstall does not support --path, so we always use cargo install here.
     let local_tools = ["mdbook-exerciser", "mdbook-course"];
     for tool in local_tools {
         let mut cmd = Command::new(cargo);