Cargo.toml

@@ -44,9 +44,18 @@ version = "1.28.1"
 features = [
 	"fs",
 	"io-util",
+	"io-std",
 	"macros",
 	"process",
 	"rt",
 	"rt-multi-thread",
 	"sync",
 ]
+
+[[bin]]
+name = "colmena"
+path = "src/main.rs"
+
+[lib]
+name = "colmena"
+path = "src/lib.rs"

src/error.rs

@@ -55,6 +55,9 @@ pub enum ColmenaError {
     #[snafu(display("Unexpected active profile: {:?}", profile))]
     ActiveProfileUnexpected { profile: Profile },
 
+    #[snafu(display("Invalid JSON from activation program: {}", error))]
+    InvalidActivationProgramJson { error: serde_json::Error },
+
     #[snafu(display("Could not determine current profile"))]
     FailedToGetCurrentProfile,
 

src/lib.rs

@@ -0,0 +1,16 @@
+#![allow(dead_code)]
+
+mod cli;
+mod command;
+mod error;
+mod job;
+mod nix;
+mod progress;
+mod troubleshooter;
+mod util;
+
+pub use nix::host::generic::Request as GenericRequest;
+pub use nix::host::generic::Response as GenericResponse;
+pub use nix::host::CopyOptions;
+pub use nix::key::{Key, UploadAt};
+pub use nix::store::StorePath;

src/nix/hive/eval.nix

@@ -197,7 +197,7 @@ let
   ];
 
   serializableSystemTypeConfigKeys = [
-    "supportsDeployment"
+    "supportsDeployment" "activationProgram" "protocol"
   ];
 
 in rec {

src/nix/hive/mod.rs

@@ -274,24 +274,38 @@ impl Hive {
         for node in selected_nodes.into_iter() {
             let config = node_configs.remove(&node).unwrap();
 
-            let host = config.to_ssh_host().map(|mut host| {
-                n_ssh += 1;
-
-                if let Some(ssh_config) = &ssh_config {
-                    host.set_ssh_config(ssh_config.clone());
-                }
-
-                if self.is_flake() {
-                    host.set_use_nix3_copy(true);
-                }
-
-                host.upcast()
-            });
-            let ssh_host = host.is_some();
-            let target = TargetNode::new(node.clone(), host, config);
-
-            if !ssh_only || ssh_host {
+            if let Some(system_type) = config.system_type.as_ref() {
+                log::debug!(
+                    "Using generic host (system_type: {}) for node {}",
+                    system_type,
+                    node.0
+                );
+                let system_config = registry.systems.get(system_type).unwrap();
+                let mut generic_host = config.to_generic_host(system_config)?;
+                generic_host.connect().await?;
+                let target = TargetNode::new(node.clone(), Some(Box::new(generic_host)), config);
                 targets.insert(node, target);
+            } else {
+                log::debug!("Using SSH host for node {}", node.0);
+                let host = config.to_ssh_host().map(|mut host| {
+                    n_ssh += 1;
+
+                    if let Some(ssh_config) = &ssh_config {
+                        host.set_ssh_config(ssh_config.clone());
+                    }
+
+                    if self.is_flake() {
+                        host.set_use_nix3_copy(true);
+                    }
+
+                    host.upcast()
+                });
+                let ssh_host = host.is_some();
+                let target = TargetNode::new(node.clone(), host, config);
+
+                if !ssh_only || ssh_host {
+                    targets.insert(node, target);
+                }
             }
         }
 

src/nix/hive/options.nix

@@ -134,6 +134,13 @@ with builtins; rec {
           type = types.nullOr types.str;
           default = "root";
         };
+        connectionUri = lib.mkOption {
+          description = mdDoc ''
+            Connection options given to the activation program.
+          '';
+          type = types.str;
+          default = "ssh://localhost";
+        };
         allowLocalDeployment = lib.mkOption {
           description = mdDoc ''
             Allow the configuration to be applied locally on the host running
@@ -258,6 +265,12 @@ with builtins; rec {
         type = types.functionTo types.unspecified;
         default = _: {};
       };
+      activationProgram = lib.mkOption {
+        description = mdDoc ''
+          Program to execute at activation time.
+        '';
+        type = types.path;
+      };
     };
   };
   registryOptions = { lib, ... }: let

src/nix/host/generic.rs

@@ -0,0 +1,265 @@
+use std::collections::HashMap;
+use std::process::Stdio;
+
+use async_trait::async_trait;
+use serde::{Deserialize, Serialize};
+use tokio::io::{AsyncBufReadExt, AsyncWriteExt, BufReader, BufWriter};
+use tokio::process::{Child, ChildStdin, ChildStdout, Command};
+
+use super::{CopyDirection, CopyOptions, Host, RebootOptions};
+use crate::error::{ColmenaError, ColmenaResult};
+use crate::job::JobHandle;
+use crate::nix::{self, Key, Profile, StorePath, SystemTypeConfig};
+
+pub type TransportId = String;
+
+#[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize)]
+pub struct Transport {
+    id: TransportId,
+    long_name: String,
+    description: String,
+}
+
+pub type GoalId = String;
+
+#[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize)]
+pub struct Goal {
+    id: GoalId,
+    long_name: String,
+    description: String,
+}
+
+/// A request to the activation program
+#[derive(Clone, Debug, Serialize, Deserialize)]
+pub enum Request {
+    Connection {
+        connection_uri: String,
+    },
+
+    /// Copy closure to/from host
+    CopyClosure {
+        path: StorePath,
+        to_host: bool,
+        options: CopyOptions,
+    },
+
+    /// Deploys the profile to host
+    Deploy {
+        goal: GoalId,
+        toplevel: StorePath,
+        options: CopyOptions,
+    },
+
+    /// Realizes the derivation
+    Realize {
+        path: StorePath,
+    },
+
+    /// Uploads keys to host
+    UploadKeys {
+        keys: HashMap<String, Key>,
+        require_ownership: bool,
+    },
+
+    Activate {
+        profile: StorePath,
+        goal: GoalId,
+    },
+
+    Reboot {
+        wait_for_boot: bool,
+    },
+}
+
+/// A response from the activation program
+#[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize)]
+pub enum Response {
+    ConnectionFailed { error: String },
+    ConnectionSucceded { supported_goals: Vec<String> },
+    Progress { phase: String },
+    NewStorePath { store_path: StorePath },
+    Failed { error: String },
+    Unsupported,
+}
+
+#[derive(Debug)]
+pub struct ActivationCommand {
+    command: Child,
+    stdin: BufWriter<ChildStdin>,
+    stdout: BufReader<ChildStdout>,
+}
+
+#[derive(Debug)]
+pub struct GenericHost {
+    activation_program: ActivationCommand,
+    connection_uri: String,
+}
+
+#[async_trait]
+impl Host for GenericHost {
+    async fn copy_closure(
+        &mut self,
+        closure: &StorePath,
+        direction: CopyDirection,
+        options: CopyOptions,
+    ) -> ColmenaResult<()> {
+        self.call_default_handler(Request::CopyClosure {
+            path: closure.clone(),
+            to_host: direction == CopyDirection::ToRemote,
+            options,
+        })
+        .await
+    }
+
+    async fn realize_remote(&mut self, derivation: &StorePath) -> ColmenaResult<Vec<StorePath>> {
+        Ok(self
+            .call(
+                Request::Realize {
+                    path: derivation.clone(),
+                },
+                move |response, mut store_paths| {
+                    match response {
+                        Response::Progress { phase } => println!("{}", phase),
+                        Response::NewStorePath { store_path } => store_paths.push(store_path),
+                        _ => (),
+                    };
+                    store_paths
+                },
+                Vec::new(),
+            )
+            .await?)
+    }
+
+    fn set_job(&mut self, _: Option<JobHandle>) {}
+
+    async fn deploy(
+        &mut self,
+        profile: &Profile,
+        goal: nix::Goal,
+        copy_options: CopyOptions,
+    ) -> ColmenaResult<()> {
+        self.call_default_handler(Request::Deploy {
+            goal: goal.to_string(),
+            toplevel: profile.as_store_path().clone(),
+            options: copy_options,
+        })
+        .await
+    }
+
+    async fn upload_keys(
+        &mut self,
+        keys: &HashMap<String, Key>,
+        require_ownership: bool,
+    ) -> ColmenaResult<()> {
+        self.call_default_handler(Request::UploadKeys {
+            keys: keys.clone(),
+            require_ownership,
+        })
+        .await
+    }
+
+    async fn get_current_system_profile(&mut self) -> ColmenaResult<Profile> {
+        Err(ColmenaError::Unsupported)
+    }
+
+    async fn get_main_system_profile(&mut self) -> ColmenaResult<Profile> {
+        Err(ColmenaError::Unsupported)
+    }
+
+    async fn activate(&mut self, profile: &Profile, goal: nix::Goal) -> ColmenaResult<()> {
+        self.call_default_handler(Request::Activate {
+            profile: profile.as_store_path().clone(),
+            goal: goal.to_string(),
+        })
+        .await
+    }
+
+    async fn reboot(&mut self, options: RebootOptions) -> ColmenaResult<()> {
+        self.call_default_handler(Request::Reboot {
+            wait_for_boot: options.wait_for_boot,
+        })
+        .await
+    }
+}
+
+impl GenericHost {
+    pub fn new(system: &SystemTypeConfig, connection_uri: String) -> ColmenaResult<GenericHost> {
+        let mut command = Command::new(system.activation_program.as_path())
+            .stdin(Stdio::piped())
+            .stdout(Stdio::piped())
+            .stderr(Stdio::inherit())
+            .spawn()?;
+
+        let stdin = BufWriter::new(command.stdin.take().unwrap());
+        let stdout = BufReader::new(command.stdout.take().unwrap());
+
+        let activation_program = ActivationCommand {
+            command,
+            stdin,
+            stdout,
+        };
+
+        Ok(Self {
+            activation_program,
+            connection_uri,
+        })
+    }
+
+    pub async fn connect(&mut self) -> ColmenaResult<()> {
+        self.call_default_handler(Request::Connection {
+            connection_uri: self.connection_uri.clone(),
+        })
+        .await
+    }
+
+    async fn call<F, T>(
+        &mut self,
+        request: Request,
+        handler: F,
+        initial_value: T,
+    ) -> ColmenaResult<T>
+    where
+        F: Fn(Response, T) -> T,
+    {
+        let json = serde_json::to_string(&request)
+            .map_err(|error| ColmenaError::InvalidActivationProgramJson { error })?;
+
+        log::trace!("giving to activation program stdin {}", json.as_str());
+
+        let stdin = &mut self.activation_program.stdin;
+        let stdout = &mut self.activation_program.stdout;
+
+        stdin.write_all(json.as_bytes()).await?;
+        stdin.write_all(b"\n").await?;
+        stdin.flush().await?;
+
+        let mut line = String::new();
+        let mut value = initial_value;
+
+        // We're reading JSONL, so we can read all the line and parse it
+        while stdout.read_line(&mut line).await.is_ok_and(|x| x != 0) {
+            if line == "\n" {
+                log::trace!("finished receiving responses from activation program");
+                break;
+            }
+            log::trace!("receiving from activation program:\n{}", line);
+            let response: Response = serde_json::from_str(line.as_str())
+                .map_err(|error| ColmenaError::InvalidActivationProgramJson { error })?;
+
+            match response {
+                Response::Progress { phase } => {
+                    log::info!("{phase}");
+                    break;
+                }
+                Response::Unsupported => return Err(ColmenaError::Unsupported),
+                _ => value = handler(response, value),
+            }
+        }
+
+        Ok(value)
+    }
+
+    async fn call_default_handler(&mut self, request: Request) -> ColmenaResult<()> {
+        self.call(request, |_, _| {}, ()).await
+    }
+}

src/nix/host/mod.rs

@@ -1,6 +1,7 @@
 use std::collections::HashMap;
 
 use async_trait::async_trait;
+use serde::{Deserialize, Serialize};
 
 use super::{Goal, Key, Profile, StorePath};
 use crate::error::{ColmenaError, ColmenaResult};
@@ -14,13 +15,16 @@ pub use local::Local;
 
 mod key_uploader;
 
-#[derive(Copy, Clone, Debug)]
+pub mod generic;
+pub use generic::GenericHost;
+
+#[derive(Copy, Clone, Debug, PartialEq, Eq, Serialize, Deserialize)]
 pub enum CopyDirection {
     ToRemote,
     FromRemote,
 }
 
-#[derive(Copy, Clone, Debug)]
+#[derive(Copy, Clone, Debug, PartialEq, Eq, Serialize, Deserialize)]
 pub struct CopyOptions {
     include_outputs: bool,
     use_substitutes: bool,

src/nix/mod.rs

@@ -10,8 +10,8 @@ use validator::{Validate, ValidationError as ValidationErrorType};
 use crate::error::{ColmenaError, ColmenaResult};
 
 pub mod host;
-use host::Ssh;
 pub use host::{CopyDirection, CopyOptions, Host, RebootOptions};
+use host::{GenericHost, Ssh};
 
 pub mod hive;
 pub use hive::{Hive, HivePath};
@@ -67,6 +67,9 @@ pub struct NodeConfig {
     #[serde(rename = "targetPort")]
     target_port: Option<u16>,
 
+    #[serde(rename = "connectionUri")]
+    connection_uri: String,
+
     #[serde(rename = "allowLocalDeployment")]
     allow_local_deployment: bool,
 
@@ -101,6 +104,9 @@ pub struct MetaConfig {
 pub struct SystemTypeConfig {
     #[serde(rename = "supportsDeployment")]
     pub supports_deployment: bool,
+
+    #[serde(rename = "activationProgram")]
+    pub activation_program: StorePath,
 }
 
 #[derive(Debug, Clone, Validate, Deserialize)]
@@ -208,6 +214,10 @@ impl NodeConfig {
             host
         })
     }
+
+    pub fn to_generic_host(&self, system_config: &SystemTypeConfig) -> ColmenaResult<GenericHost> {
+        GenericHost::new(system_config, self.connection_uri.clone())
+    }
 }
 
 impl NixFlags {