Stream provision output live and fix generated key permissions

- Add ssh::exec_streaming() that prints stdout/stderr as data arrives
  instead of buffering until command completion. Provision scripts now
  show output in real time without tracing annotation.
- Set 0600 permissions on generated SSH private keys so OpenSSH
  accepts them.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

crates/vm-manager/src/provision.rs

@@ -11,8 +11,8 @@ use crate::vmfile::{FileProvision, ProvisionDef, ShellProvision, resolve_path};
 
 /// Run all provision steps on an established SSH session.
 ///
-/// If `log_dir` is provided, all stdout/stderr from provision steps is appended to
+/// Output from shell provisioners is streamed to stdout/stderr in real time.
-/// `provision.log` in that directory.
+/// If `log_dir` is provided, output is also appended to `provision.log`.
 pub fn run_provisions(
     sess: &Session,
     provisions: &[ProvisionDef],
@@ -34,16 +34,6 @@ pub fn run_provisions(
     Ok(())
 }
 
-/// Log provision output to tracing and optionally to a file.
-fn log_output(vm_name: &str, step: usize, label: &str, stdout: &str, stderr: &str) {
-    for line in stdout.lines() {
-        info!(vm = %vm_name, step, "[{label}:stdout] {line}");
-    }
-    for line in stderr.lines() {
-        info!(vm = %vm_name, step, "[{label}:stderr] {line}");
-    }
-}
-
 /// Append provision output to a log file in the given directory.
 pub fn append_provision_log(log_dir: &Path, step: usize, label: &str, stdout: &str, stderr: &str) {
     let log_path = log_dir.join("provision.log");
@@ -77,14 +67,19 @@ fn run_shell(
 ) -> Result<()> {
     if let Some(ref cmd) = shell.inline {
         info!(vm = %vm_name, step, cmd = %cmd, "running inline shell provision");
-        let (stdout, stderr, exit_code) =
+
-            ssh::exec(sess, cmd).map_err(|e| VmError::ProvisionFailed {
+        let (stdout, stderr, exit_code) = ssh::exec_streaming(
+            sess,
+            cmd,
+            std::io::stdout(),
+            std::io::stderr(),
+        )
+        .map_err(|e| VmError::ProvisionFailed {
             vm: vm_name.into(),
             step,
             detail: format!("shell exec: {e}"),
         })?;
 
-        log_output(vm_name, step, cmd, &stdout, &stderr);
         if let Some(dir) = log_dir {
             append_provision_log(dir, step, cmd, &stdout, &stderr);
         }
@@ -115,14 +110,18 @@ fn run_shell(
 
         // Make executable and run
         let run_cmd = format!("chmod +x {remote_path_str} && {remote_path_str}");
-        let (stdout, stderr, exit_code) =
+        let (stdout, stderr, exit_code) = ssh::exec_streaming(
-            ssh::exec(sess, &run_cmd).map_err(|e| VmError::ProvisionFailed {
+            sess,
+            &run_cmd,
+            std::io::stdout(),
+            std::io::stderr(),
+        )
+        .map_err(|e| VmError::ProvisionFailed {
             vm: vm_name.into(),
             step,
             detail: format!("script exec: {e}"),
         })?;
 
-        log_output(vm_name, step, script_raw, &stdout, &stderr);
         if let Some(dir) = log_dir {
             append_provision_log(dir, step, script_raw, &stdout, &stderr);
         }

crates/vm-manager/src/ssh.rs

@@ -91,6 +91,94 @@ pub fn exec(sess: &Session, cmd: &str) -> Result<(String, String, i32)> {
     Ok((stdout, stderr, exit_code))
 }
 
+/// Execute a command and stream stdout/stderr to the provided writers as data arrives.
+///
+/// Returns `(stdout_collected, stderr_collected, exit_code)`.
+pub fn exec_streaming<W1: std::io::Write, W2: std::io::Write>(
+    sess: &Session,
+    cmd: &str,
+    mut out: W1,
+    mut err: W2,
+) -> Result<(String, String, i32)> {
+    let mut channel = sess.channel_session().map_err(|e| VmError::SshFailed {
+        detail: format!("channel session: {e}"),
+    })?;
+
+    // Non-blocking mode so we can interleave stdout and stderr reads
+    sess.set_blocking(false);
+
+    channel.exec(cmd).map_err(|e| {
+        sess.set_blocking(true);
+        VmError::SshFailed {
+            detail: format!("exec '{cmd}': {e}"),
+        }
+    })?;
+
+    let mut stdout_buf = Vec::new();
+    let mut stderr_buf = Vec::new();
+    let mut buf = [0u8; 8192];
+
+    loop {
+        let mut progress = false;
+
+        // Read stdout
+        match channel.read(&mut buf) {
+            Ok(0) => {}
+            Ok(n) => {
+                let _ = out.write_all(&buf[..n]);
+                let _ = out.flush();
+                stdout_buf.extend_from_slice(&buf[..n]);
+                progress = true;
+            }
+            Err(ref e) if e.kind() == std::io::ErrorKind::WouldBlock => {}
+            Err(e) => {
+                sess.set_blocking(true);
+                return Err(VmError::SshFailed {
+                    detail: format!("read stdout: {e}"),
+                });
+            }
+        }
+
+        // Read stderr
+        match channel.stderr().read(&mut buf) {
+            Ok(0) => {}
+            Ok(n) => {
+                let _ = err.write_all(&buf[..n]);
+                let _ = err.flush();
+                stderr_buf.extend_from_slice(&buf[..n]);
+                progress = true;
+            }
+            Err(ref e) if e.kind() == std::io::ErrorKind::WouldBlock => {}
+            Err(e) => {
+                sess.set_blocking(true);
+                return Err(VmError::SshFailed {
+                    detail: format!("read stderr: {e}"),
+                });
+            }
+        }
+
+        if channel.eof() && !progress {
+            break;
+        }
+
+        if !progress {
+            std::thread::sleep(Duration::from_millis(50));
+        }
+    }
+
+    sess.set_blocking(true);
+
+    channel.wait_close().map_err(|e| VmError::SshFailed {
+        detail: format!("wait close: {e}"),
+    })?;
+    let exit_code = channel.exit_status().unwrap_or(1);
+
+    let stdout = String::from_utf8_lossy(&stdout_buf).into_owned();
+    let stderr = String::from_utf8_lossy(&stderr_buf).into_owned();
+
+    Ok((stdout, stderr, exit_code))
+}
+
 /// Upload a local file to a remote path via SFTP.
 pub fn upload(sess: &Session, local: &Path, remote: &Path) -> Result<()> {
     let sftp = sess.sftp().map_err(|e| VmError::SshFailed {

crates/vmctl/src/commands/mod.rs

@@ -97,16 +97,23 @@ fn ssh_port_for_handle(handle: &VmHandle) -> u16 {
 const GENERATED_KEY_FILE: &str = "id_ed25519_generated";
 
 /// Persist a generated SSH private key PEM to the VM's work directory (if present).
+///
+/// The file is written with 0600 permissions so that OpenSSH accepts it.
 async fn save_generated_ssh_key(
     spec: &vm_manager::VmSpec,
     handle: &VmHandle,
 ) -> miette::Result<()> {
+    use std::os::unix::fs::PermissionsExt;
+
     if let Some(ref ssh) = spec.ssh {
         if let Some(ref pem) = ssh.private_key_pem {
             let key_path = handle.work_dir.join(GENERATED_KEY_FILE);
             tokio::fs::write(&key_path, pem)
                 .await
                 .map_err(|e| miette::miette!("failed to save generated SSH key: {e}"))?;
+            tokio::fs::set_permissions(&key_path, std::fs::Permissions::from_mode(0o600))
+                .await
+                .map_err(|e| miette::miette!("failed to set SSH key permissions: {e}"))?;
         }
     }
     Ok(())