Implement --target-host

nix/lib.nix

@@ -88,22 +88,39 @@ in
         text = lib.generators.toJSON { } etcFiles;
       };
 
+      registerProfileScript = pkgs.writeShellScript "register-profile" ''
+        ${system-manager}/bin/system-manager generate \
+          --store-path "$(dirname $(realpath $(dirname ''${0})))" \
+          "$@"
+      '';
+
       activationScript = pkgs.writeShellScript "activate" ''
         ${system-manager}/bin/system-manager activate \
-          --store-path "$(realpath $(dirname ''${0}))" \
+          --store-path "$(dirname $(realpath $(dirname ''${0})))" \
           "$@"
       '';
 
       deactivationScript = pkgs.writeShellScript "deactivate" ''
         ${system-manager}/bin/system-manager deactivate "$@"
       '';
+
+      linkFarmEntryFromDrv = drv: {
+        name = drv.name;
+        path = drv;
+      };
+
+      linkFarmBinEntryFromDrv = drv: {
+        name = "bin/${drv.name}";
+        path = drv;
+      };
     in
     returnIfNoAssertions (
-      pkgs.linkFarmFromDrvs "system-manager" [
-        servicesPath
-        etcPath
-        activationScript
-        deactivationScript
+      pkgs.linkFarm "system-manager" [
+        (linkFarmEntryFromDrv servicesPath)
+        (linkFarmEntryFromDrv etcPath)
+        (linkFarmBinEntryFromDrv activationScript)
+        (linkFarmBinEntryFromDrv deactivationScript)
+        (linkFarmBinEntryFromDrv registerProfileScript)
       ]
     );
 }

src/activate.rs

@@ -5,17 +5,18 @@ use anyhow::Result;
 
 use crate::StorePath;
 
-pub fn activate(store_path: StorePath, ephemeral: bool) -> Result<()> {
+pub fn activate(store_path: &StorePath, ephemeral: bool) -> Result<()> {
     log::info!("Activating system-manager profile: {store_path}");
     if ephemeral {
         log::info!("Running in ephemeral mode");
     }
 
-    etc_files::activate(&store_path, ephemeral)?;
-    services::activate(&store_path, ephemeral)?;
+    etc_files::activate(store_path, ephemeral)?;
+    services::activate(store_path, ephemeral)?;
     Ok(())
 }
 
+// TODO should we also remove the GC root for the profile if it exists?
 pub fn deactivate() -> Result<()> {
     log::info!("Deactivating system-manager");
     etc_files::deactivate()?;

src/generate.rs

@@ -14,28 +14,18 @@ struct NixBuildOutput {
     outputs: HashMap<String, String>,
 }
 
-pub fn generate(flake_uri: &str) -> Result<StorePath> {
-    let store_path = build(flake_uri)?;
+pub fn generate(store_path: &StorePath) -> Result<()> {
     let profile_dir = Path::new(PROFILE_DIR);
     let profile_name = Path::new(PROFILE_NAME);
 
     log::info!("Creating new generation from {store_path}");
-    install_nix_profile(&store_path, profile_dir, profile_name)?;
+    install_nix_profile(store_path, profile_dir, profile_name)?;
 
     log::info!("Registering GC root...");
     create_gcroot(GCROOT_PATH, &profile_dir.join(profile_name))?;
 
     log::info!("Done");
-    Ok(store_path)
-}
-
-pub fn build(flake_uri: &str) -> Result<StorePath> {
-    // FIXME: we should not hard-code the system here
-    let flake_attr = format!("{FLAKE_ATTR}.x86_64-linux");
-
-    log::info!("Building new system-manager generation...");
-    log::info!("Running nix build...");
-    run_nix_build(flake_uri, &flake_attr).and_then(get_store_path)
+    Ok(())
 }
 
 fn install_nix_profile(
@@ -61,6 +51,15 @@ fn create_gcroot(gcroot_path: &str, profile_path: &Path) -> Result<()> {
     create_store_link(&store_path, Path::new(gcroot_path))
 }
 
+pub fn build(flake_uri: &str) -> Result<StorePath> {
+    // FIXME: we should not hard-code the system here
+    let flake_attr = format!("{FLAKE_ATTR}.x86_64-linux");
+
+    log::info!("Building new system-manager generation...");
+    log::info!("Running nix build...");
+    run_nix_build(flake_uri, &flake_attr).and_then(get_store_path)
+}
+
 fn get_store_path(nix_build_result: process::Output) -> Result<StorePath> {
     if nix_build_result.status.success() {
         String::from_utf8(nix_build_result.stdout)

src/main.rs

@@ -1,4 +1,4 @@
-use std::process::ExitCode;
+use std::process::{self, ExitCode, ExitStatus};
 
 use anyhow::Result;
 use clap::Parser;
@@ -10,6 +10,13 @@ use system_manager::StorePath;
 struct Args {
     #[command(subcommand)]
     action: Action,
+
+    #[arg(long)]
+    /// The host to deploy the system-manager profile to
+    target_host: Option<String>,
+
+    #[arg(long, action)]
+    use_remote_sudo: bool,
 }
 
 #[derive(clap::Args, Debug)]
@@ -19,6 +26,17 @@ struct BuildArgs {
     flake_uri: String,
 }
 
+#[derive(clap::Args, Debug)]
+struct GenerateArgs {
+    #[arg(long)]
+    /// The flake defining the system-manager profile
+    flake_uri: Option<String>,
+
+    #[arg(long)]
+    /// The store path containing the system-manager profile
+    store_path: Option<StorePath>,
+}
+
 #[derive(clap::Args, Debug)]
 struct ActivationArgs {
     #[arg(long, action)]
@@ -45,7 +63,7 @@ enum Action {
     /// Generate a new system-manager generation
     Generate {
         #[command(flatten)]
-        build_args: BuildArgs,
+        generate_args: GenerateArgs,
     },
     /// Generate a new system-manager generation and activate it
     Switch {
@@ -57,42 +75,69 @@ enum Action {
 }
 
 fn main() -> ExitCode {
-    let args = Args::parse();
-
     // FIXME: set default level to info
     env_logger::Builder::from_env(env_logger::Env::default().default_filter_or("debug")).init();
-    handle_toplevel_error(go(args.action))
+    handle_toplevel_error(go(Args::parse()))
 }
 
-fn go(action: Action) -> Result<()> {
+fn go(args: Args) -> Result<()> {
+    let Args {
+        action,
+        target_host,
+        use_remote_sudo,
+    } = args;
+
     match action {
         Action::Activate {
             store_path,
             activation_args: ActivationArgs { ephemeral },
         } => {
-            check_root()?;
-            activate(store_path, ephemeral)
+            // FIXME handle target_host
+            copy_closure(&store_path, &target_host)?;
+            activate(&store_path, ephemeral, &target_host, use_remote_sudo)
         }
         Action::Build {
             build_args: BuildArgs { flake_uri },
         } => build(flake_uri),
         Action::Deactivate => {
             check_root()?;
+            // FIXME handle target_host
             deactivate()
         }
-        Action::Generate {
-            build_args: BuildArgs { flake_uri },
-        } => {
-            check_root()?;
-            generate(flake_uri).map(|_| ())
+        Action::Generate { generate_args } => {
+            generate(generate_args, &target_host, use_remote_sudo)
         }
         Action::Switch {
             build_args: BuildArgs { flake_uri },
             activation_args: ActivationArgs { ephemeral },
         } => {
-            check_root()?;
-            let store_path = generate(flake_uri)?;
-            activate(store_path, ephemeral)
+            let store_path = do_build(flake_uri)?;
+            copy_closure(&store_path, &target_host)?;
+            do_generate(&store_path, &target_host, use_remote_sudo)?;
+            activate(&store_path, ephemeral, &target_host, use_remote_sudo)
+        }
+    }
+}
+
+fn generate(args: GenerateArgs, target_host: &Option<String>, use_remote_sudo: bool) -> Result<()> {
+    match args {
+        GenerateArgs {
+            flake_uri: Some(flake_uri),
+            store_path: None,
+        } => {
+            let store_path = do_build(flake_uri)?;
+            copy_closure(&store_path, target_host)?;
+            do_generate(&store_path, target_host, use_remote_sudo)
+        }
+        GenerateArgs {
+            flake_uri: None,
+            store_path: Some(store_path),
+        } => {
+            copy_closure(&store_path, target_host)?;
+            do_generate(&store_path, target_host, use_remote_sudo)
+        }
+        _ => {
+            anyhow::bail!("Supply either a flake URI or a store path.")
         }
     }
 }
@@ -109,18 +154,75 @@ fn do_build(flake_uri: String) -> Result<StorePath> {
     system_manager::generate::build(&flake_uri)
 }
 
-fn generate(flake_uri: String) -> Result<StorePath> {
-    system_manager::generate::generate(&flake_uri)
+fn do_generate(
+    store_path: &StorePath,
+    target_host: &Option<String>,
+    use_remote_sudo: bool,
+) -> Result<()> {
+    if let Some(target_host) = target_host {
+        invoke_remote_script(store_path, "register-profile", target_host, use_remote_sudo)?;
+        Ok(())
+    } else {
+        check_root()?;
+        system_manager::generate::generate(store_path)
+    }
 }
 
-fn activate(store_path: StorePath, ephemeral: bool) -> Result<()> {
-    system_manager::activate::activate(store_path, ephemeral)
+fn activate(
+    store_path: &StorePath,
+    ephemeral: bool,
+    target_host: &Option<String>,
+    use_remote_sudo: bool,
+) -> Result<()> {
+    if let Some(target_host) = target_host {
+        invoke_remote_script(store_path, "activate", target_host, use_remote_sudo)?;
+        Ok(())
+    } else {
+        check_root()?;
+        system_manager::activate::activate(store_path, ephemeral)
+    }
 }
 
 fn deactivate() -> Result<()> {
     system_manager::activate::deactivate()
 }
 
+fn copy_closure(store_path: &StorePath, target_host: &Option<String>) -> Result<()> {
+    target_host
+        .as_ref()
+        .map_or(Ok(()), |target| do_copy_closure(store_path, target))
+}
+
+fn do_copy_closure(store_path: &StorePath, target_host: &str) -> Result<()> {
+    process::Command::new("nix-copy-closure")
+        .arg("--to")
+        .arg(target_host)
+        .arg("--use-substitutes")
+        .arg(&store_path.store_path)
+        .stdout(process::Stdio::inherit())
+        .stderr(process::Stdio::inherit())
+        .status()?;
+    Ok(())
+}
+
+fn invoke_remote_script(
+    store_path: &StorePath,
+    script_name: &str,
+    target_host: &str,
+    use_remote_sudo: bool,
+) -> Result<ExitStatus> {
+    let mut cmd = process::Command::new("ssh");
+    cmd.arg(target_host).arg("--");
+    if use_remote_sudo {
+        cmd.arg("sudo");
+    }
+    cmd.arg(format!("{store_path}/bin/{script_name}"))
+        .stdout(process::Stdio::inherit())
+        .stderr(process::Stdio::inherit())
+        .status()
+        .map_err(anyhow::Error::from)
+}
+
 fn check_root() -> Result<()> {
     if !nix::unistd::Uid::is_root(nix::unistd::getuid()) {
         anyhow::bail!("We need root permissions.")