azcomputerguru
a062a825ea
Comprehensive specification for terminal-based remote access to headless Linux servers (no X11/Wayland GUI): Core Capabilities: - PTY spawn via openpty() + fork/exec shell (/bin/bash or $SHELL) - Terminal I/O: PTY output → TerminalData protobuf → WebSocket relay - Input: keyboard → TerminalInput protobuf → PTY master write - Resize: SIGWINCH on terminal window resize, TIOCSWINSZ ioctl - Auto-detection: agent detects headless environment (no DISPLAY) at runtime Viewer: - xterm.js-based web terminal (80x24 default, resizable) - Full ANSI/VT100 support (colors, cursor control, vim/nano/htop) - Same protobuf-over-WSS protocol, support-code/agent-key auth - Dashboard shows "Terminal" badge, routes to terminal viewer Use Cases: - Server management (headless Ubuntu Server, VMs, containers) - Emergency recovery (systemd rescue mode, single-user mode) - Container debugging (exec into running containers) - SSH replacement with centralized audit logging Protobuf Extensions: - TerminalData, TerminalInput, TerminalResize messages - AgentStatus.terminal_mode flag Security: - Run agent as unprivileged user + sudo for privileged commands - Session recording to terminal_recordings table (asciicast format) - Same auth model as GUI agents (support-code / per-agent key) Estimated effort: Medium (4-6 weeks) Priority: P2 (server management is market-critical) Extends SPEC-010 Linux agent with PTY alternative to screen capture. Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>
628 lines
23 KiB
Markdown
628 lines
23 KiB
Markdown
# SPEC-012: Headless Linux Mode (Direct TTY Access)
|
|
|
|
**Status:** Proposed
|
|
**Priority:** P2
|
|
**Requested By:** Mike Swanson (2026-05-30)
|
|
**Estimated Effort:** Medium (4-6 weeks)
|
|
|
|
## Overview
|
|
|
|
Enable GuruConnect agent support for headless Linux servers (no X11/Wayland GUI) by providing direct terminal (TTY) access instead of screen capture. This addresses a critical server management use case: remote terminal access to Linux servers, VMs, and containers that run without a graphical desktop environment. Unlike SSH, this integrates with the GuruConnect dashboard for centralized access, audit logging, and support-code workflows. The viewer displays a terminal emulator (xterm.js-based web viewer or native terminal in the desktop viewer) connected to a pseudo-TTY (PTY) on the target server. Success criteria: technician can manage a headless Ubuntu Server 22.04 VM via GuruConnect dashboard with same authentication and session model as GUI agents, full terminal capabilities (colors, cursor control, vim/nano editing), and zero X11/Wayland dependencies on the target.
|
|
|
|
**Use Cases:**
|
|
- Remote terminal access to headless Linux servers (web hosting, databases, Docker hosts)
|
|
- Container debugging (exec into running containers via GuruConnect)
|
|
- Emergency server recovery (systemd rescue mode, single-user mode)
|
|
- MSP consolidation: one tool for both desktop support (GUI) and server management (terminal)
|
|
|
|
**Success Criteria:**
|
|
- GuruConnect agent runs on Ubuntu Server 22.04 minimal install (no desktop packages)
|
|
- Viewer sees full-color, interactive terminal (80x24 or larger, resizable)
|
|
- Full terminal capabilities: ANSI colors, cursor positioning, vim/nano/htop work correctly
|
|
- Same protobuf-over-WSS transport, support-code and persistent-agent authentication
|
|
- Audit logging: session recording (terminal output captured to `events` table or file)
|
|
|
|
## Scope
|
|
|
|
### Included in v1
|
|
|
|
**Headless Agent Mode:**
|
|
- Detect headless environment (no DISPLAY, no X11/Wayland libraries) at runtime
|
|
- Spawn pseudo-TTY (PTY) via `openpty()` + fork/exec shell (`/bin/bash -l` or user's `$SHELL`)
|
|
- Terminal I/O: read PTY output → encode as protobuf `TerminalData` → send via WebSocket
|
|
- Input: receive protobuf `TerminalInput` → write to PTY master
|
|
- Terminal resize: handle `TerminalResize` message → send `SIGWINCH` to PTY
|
|
- Fallback shell selection: `$SHELL` env var → `/bin/bash` → `/bin/sh`
|
|
- Same agent binary as GUI mode: `guruconnect` detects headless and switches mode automatically
|
|
- Graceful PTY cleanup on session end (send exit command, wait for shell exit, close PTY)
|
|
|
|
**Viewer (Web Viewer):**
|
|
- xterm.js-based terminal emulator embedded in `viewer.html`
|
|
- Connects to same `/ws/viewer` endpoint with session JWT
|
|
- Relay server detects `TerminalData` frames (not `FrameData`) and routes accordingly
|
|
- Terminal controls: resize on window resize, copy/paste support, configurable font size
|
|
- Session toolbar: connection status, terminal size (e.g., "80x24"), reconnect button
|
|
|
|
**Viewer (Native Desktop Viewer - optional Phase 2):**
|
|
- Defer native viewer terminal support to Phase 2
|
|
- v1: web viewer only for terminal sessions (show "Open in browser" prompt if launched via `guruconnect://`)
|
|
|
|
**Protobuf Protocol:**
|
|
- New message types: `TerminalData` (PTY output), `TerminalInput` (keyboard input), `TerminalResize` (window size)
|
|
- `AgentStatus` includes `terminal_mode: bool` flag (true for headless agents)
|
|
- Dashboard shows terminal icon for headless agents, camera icon for GUI agents
|
|
|
|
**Dashboard:**
|
|
- Detect `terminal_mode: true` in agent status
|
|
- "Connect" button opens web viewer in terminal mode (not screen capture mode)
|
|
- Agent list shows "Terminal" badge for headless agents
|
|
|
|
**Session Recording (Audit):**
|
|
- Log all terminal I/O to `events` table or separate `terminal_sessions` table
|
|
- Playback: recorded session can be replayed as "terminal recording" (asciicast format or raw PTY dump)
|
|
|
|
### Explicitly out of scope
|
|
|
|
- **GUI mode on headless agents** — v1 is terminal-only; no attempt to start Xvfb or launch GUI apps
|
|
- **SSH key management** — agent uses GuruConnect auth (support code / agent key), not SSH keys
|
|
- **File transfer via terminal** — defer to SPEC (file transfer is a separate roadmap item for all agent types)
|
|
- **Multi-user terminal sessions** — v1 is single-session PTY; no tmux/screen built-in sharing
|
|
- **Windows terminal mode** — defer; Windows Server typically has GUI (RDP) or SSH (OpenSSH)
|
|
- **macOS terminal mode** — defer; macOS servers are rare and typically have GUI access
|
|
|
|
## Architecture
|
|
|
|
### Agent PTY Handling
|
|
|
|
**Headless detection:**
|
|
|
|
```rust
|
|
// agent/src/platform/linux/headless.rs
|
|
pub fn is_headless() -> bool {
|
|
// Check if DISPLAY is unset and no X11/Wayland session detected
|
|
std::env::var("DISPLAY").is_err() &&
|
|
std::env::var("WAYLAND_DISPLAY").is_err() &&
|
|
!std::path::Path::new("/tmp/.X11-unix").exists()
|
|
}
|
|
```
|
|
|
|
**PTY spawn:**
|
|
|
|
```rust
|
|
// agent/src/platform/linux/pty.rs
|
|
use libc::{openpty, fork, execvp, dup2, STDIN_FILENO, STDOUT_FILENO, STDERR_FILENO, winsize, TIOCSWINSZ};
|
|
use std::os::unix::io::RawFd;
|
|
|
|
pub struct PtySession {
|
|
master_fd: RawFd,
|
|
child_pid: libc::pid_t,
|
|
cols: u16,
|
|
rows: u16,
|
|
}
|
|
|
|
impl PtySession {
|
|
pub fn spawn(shell: &str, cols: u16, rows: u16) -> Result<Self> {
|
|
let mut master_fd: RawFd = 0;
|
|
let mut slave_fd: RawFd = 0;
|
|
let mut winsize = winsize {
|
|
ws_row: rows,
|
|
ws_col: cols,
|
|
ws_xpixel: 0,
|
|
ws_ypixel: 0,
|
|
};
|
|
|
|
unsafe {
|
|
if openpty(&mut master_fd, &mut slave_fd, std::ptr::null_mut(),
|
|
std::ptr::null(), &mut winsize as *mut _) != 0 {
|
|
return Err(anyhow!("openpty failed"));
|
|
}
|
|
|
|
let pid = fork();
|
|
if pid == 0 {
|
|
// Child process: exec shell
|
|
dup2(slave_fd, STDIN_FILENO);
|
|
dup2(slave_fd, STDOUT_FILENO);
|
|
dup2(slave_fd, STDERR_FILENO);
|
|
libc::close(master_fd);
|
|
libc::close(slave_fd);
|
|
|
|
let shell_cstr = CString::new(shell)?;
|
|
let args = [shell_cstr.as_ptr(), std::ptr::null()];
|
|
execvp(shell_cstr.as_ptr(), args.as_ptr());
|
|
std::process::exit(1); // exec failed
|
|
} else {
|
|
// Parent process: close slave, return master FD
|
|
libc::close(slave_fd);
|
|
Ok(PtySession {
|
|
master_fd,
|
|
child_pid: pid,
|
|
cols,
|
|
rows,
|
|
})
|
|
}
|
|
}
|
|
}
|
|
|
|
pub fn read(&self, buf: &mut [u8]) -> Result<usize> {
|
|
unsafe {
|
|
let n = libc::read(self.master_fd, buf.as_mut_ptr() as *mut _, buf.len());
|
|
if n < 0 {
|
|
Err(anyhow!("PTY read failed"))
|
|
} else {
|
|
Ok(n as usize)
|
|
}
|
|
}
|
|
}
|
|
|
|
pub fn write(&self, data: &[u8]) -> Result<()> {
|
|
unsafe {
|
|
let n = libc::write(self.master_fd, data.as_ptr() as *const _, data.len());
|
|
if n < 0 {
|
|
Err(anyhow!("PTY write failed"))
|
|
} else {
|
|
Ok(())
|
|
}
|
|
}
|
|
}
|
|
|
|
pub fn resize(&mut self, cols: u16, rows: u16) -> Result<()> {
|
|
self.cols = cols;
|
|
self.rows = rows;
|
|
let winsize = winsize {
|
|
ws_row: rows,
|
|
ws_col: cols,
|
|
ws_xpixel: 0,
|
|
ws_ypixel: 0,
|
|
};
|
|
unsafe {
|
|
if libc::ioctl(self.master_fd, TIOCSWINSZ, &winsize as *const _) != 0 {
|
|
return Err(anyhow!("TIOCSWINSZ failed"));
|
|
}
|
|
}
|
|
// Send SIGWINCH to child process group
|
|
unsafe { libc::kill(-self.child_pid, libc::SIGWINCH); }
|
|
Ok(())
|
|
}
|
|
}
|
|
|
|
impl Drop for PtySession {
|
|
fn drop(&mut self) {
|
|
unsafe {
|
|
libc::close(self.master_fd);
|
|
// Send SIGTERM to child, wait briefly, then SIGKILL if still alive
|
|
libc::kill(self.child_pid, libc::SIGTERM);
|
|
std::thread::sleep(std::time::Duration::from_millis(500));
|
|
libc::waitpid(self.child_pid, std::ptr::null_mut(), libc::WNOHANG);
|
|
}
|
|
}
|
|
}
|
|
```
|
|
|
|
**Agent session loop:**
|
|
|
|
```rust
|
|
// agent/src/session/terminal.rs
|
|
pub async fn run_terminal_session(ws: WebSocketClient, support_code: String) -> Result<()> {
|
|
let shell = std::env::var("SHELL").unwrap_or_else(|_| "/bin/bash".to_string());
|
|
let mut pty = PtySession::spawn(&shell, 80, 24)?;
|
|
|
|
// Status update: terminal mode
|
|
ws.send(AgentStatus {
|
|
terminal_mode: true,
|
|
os: "Linux".to_string(),
|
|
// ...
|
|
}).await?;
|
|
|
|
let mut buf = vec![0u8; 4096];
|
|
loop {
|
|
tokio::select! {
|
|
// Read PTY output, send to relay
|
|
Ok(n) = tokio::task::spawn_blocking({
|
|
let master = pty.master_fd;
|
|
move || unsafe { libc::read(master, buf.as_mut_ptr() as *mut _, buf.len()) }
|
|
}) => {
|
|
if n > 0 {
|
|
ws.send(TerminalData {
|
|
data: buf[..n as usize].to_vec(),
|
|
}).await?;
|
|
}
|
|
}
|
|
|
|
// Receive input from relay, write to PTY
|
|
Some(msg) = ws.recv() => {
|
|
match msg {
|
|
Message::TerminalInput(input) => {
|
|
pty.write(&input.data)?;
|
|
}
|
|
Message::TerminalResize(resize) => {
|
|
pty.resize(resize.cols, resize.rows)?;
|
|
}
|
|
Message::Disconnect => break,
|
|
_ => {}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
Ok(())
|
|
}
|
|
```
|
|
|
|
### Protobuf Protocol Extensions
|
|
|
|
```protobuf
|
|
// proto/guruconnect.proto
|
|
|
|
message AgentStatus {
|
|
// Existing fields...
|
|
optional bool terminal_mode = 21; // true for headless agents
|
|
}
|
|
|
|
message TerminalData {
|
|
bytes data = 1; // PTY raw output (may include ANSI escape sequences)
|
|
}
|
|
|
|
message TerminalInput {
|
|
bytes data = 1; // Keyboard input from viewer (UTF-8 encoded)
|
|
}
|
|
|
|
message TerminalResize {
|
|
uint32 cols = 1; // Terminal width (characters)
|
|
uint32 rows = 2; // Terminal height (lines)
|
|
}
|
|
|
|
// Update AgentMessage and ViewerMessage unions
|
|
message AgentMessage {
|
|
oneof message {
|
|
AgentStatus status = 1;
|
|
FrameData frame = 2;
|
|
TerminalData terminal_data = 10; // NEW
|
|
}
|
|
}
|
|
|
|
message ViewerMessage {
|
|
oneof message {
|
|
InputEvent input = 1;
|
|
TerminalInput terminal_input = 10; // NEW
|
|
TerminalResize terminal_resize = 11; // NEW
|
|
}
|
|
}
|
|
```
|
|
|
|
### Relay Server Changes
|
|
|
|
**Route terminal vs. screen capture sessions:**
|
|
|
|
```rust
|
|
// server/src/relay/mod.rs
|
|
async fn handle_agent_message(msg: AgentMessage, session: &Session) {
|
|
match msg.message {
|
|
Some(agent_message::Message::Status(status)) => {
|
|
session.terminal_mode = status.terminal_mode.unwrap_or(false);
|
|
// Store in DB: UPDATE sessions SET terminal_mode = ? WHERE id = ?
|
|
}
|
|
Some(agent_message::Message::TerminalData(data)) => {
|
|
// Forward to viewer WebSocket
|
|
if let Some(viewer_ws) = session.viewer_ws.lock().await.as_mut() {
|
|
viewer_ws.send(ViewerMessage {
|
|
message: Some(viewer_message::Message::TerminalData(data))
|
|
}).await?;
|
|
}
|
|
// Optional: append to terminal_recording buffer for audit
|
|
}
|
|
Some(agent_message::Message::Frame(frame)) => {
|
|
// Existing screen capture logic...
|
|
}
|
|
_ => {}
|
|
}
|
|
}
|
|
|
|
async fn handle_viewer_message(msg: ViewerMessage, session: &Session) {
|
|
match msg.message {
|
|
Some(viewer_message::Message::TerminalInput(input)) => {
|
|
// Forward to agent WebSocket
|
|
if let Some(agent_ws) = session.agent_ws.lock().await.as_mut() {
|
|
agent_ws.send(AgentMessage {
|
|
message: Some(agent_message::Message::TerminalInput(input))
|
|
}).await?;
|
|
}
|
|
}
|
|
Some(viewer_message::Message::TerminalResize(resize)) => {
|
|
// Forward resize to agent
|
|
if let Some(agent_ws) = session.agent_ws.lock().await.as_mut() {
|
|
agent_ws.send(AgentMessage {
|
|
message: Some(agent_message::Message::TerminalResize(resize))
|
|
}).await?;
|
|
}
|
|
}
|
|
Some(viewer_message::Message::Input(input)) => {
|
|
// Existing GUI input logic...
|
|
}
|
|
_ => {}
|
|
}
|
|
}
|
|
```
|
|
|
|
### Web Viewer (xterm.js)
|
|
|
|
**HTML template:**
|
|
|
|
```html
|
|
<!-- server/static/viewer-terminal.html -->
|
|
<!DOCTYPE html>
|
|
<html>
|
|
<head>
|
|
<title>GuruConnect Terminal</title>
|
|
<link rel="stylesheet" href="/vendor/xterm/xterm.css" />
|
|
<script src="/vendor/xterm/xterm.js"></script>
|
|
<script src="/vendor/xterm/xterm-addon-fit.js"></script>
|
|
<style>
|
|
#terminal { height: 100vh; }
|
|
.toolbar { background: #333; color: #fff; padding: 8px; }
|
|
</style>
|
|
</head>
|
|
<body>
|
|
<div class="toolbar">
|
|
<span id="status">Connecting...</span>
|
|
<span id="size" style="float: right;">80x24</span>
|
|
</div>
|
|
<div id="terminal"></div>
|
|
<script>
|
|
const term = new Terminal({
|
|
cursorBlink: true,
|
|
fontSize: 14,
|
|
fontFamily: 'Consolas, "Courier New", monospace',
|
|
theme: {
|
|
background: '#1e1e1e',
|
|
foreground: '#d4d4d4',
|
|
}
|
|
});
|
|
const fitAddon = new FitAddon.FitAddon();
|
|
term.loadAddon(fitAddon);
|
|
term.open(document.getElementById('terminal'));
|
|
fitAddon.fit();
|
|
|
|
const ws = new WebSocket(`wss://${location.host}/ws/viewer?token=${TOKEN}&session=${SESSION_ID}`);
|
|
|
|
ws.onopen = () => {
|
|
document.getElementById('status').textContent = 'Connected';
|
|
// Send initial terminal size
|
|
ws.send(encodeTerminalResize(term.cols, term.rows));
|
|
};
|
|
|
|
ws.onmessage = (event) => {
|
|
const msg = decodeProtobuf(event.data);
|
|
if (msg.terminal_data) {
|
|
term.write(new Uint8Array(msg.terminal_data.data));
|
|
}
|
|
};
|
|
|
|
term.onData((data) => {
|
|
ws.send(encodeTerminalInput(data));
|
|
});
|
|
|
|
term.onResize(({ cols, rows }) => {
|
|
document.getElementById('size').textContent = `${cols}x${rows}`;
|
|
ws.send(encodeTerminalResize(cols, rows));
|
|
});
|
|
|
|
window.addEventListener('resize', () => fitAddon.fit());
|
|
</script>
|
|
</body>
|
|
</html>
|
|
```
|
|
|
|
### Dashboard Detection
|
|
|
|
```javascript
|
|
// server/static/dashboard.js
|
|
function renderAgentRow(agent) {
|
|
const icon = agent.terminal_mode
|
|
? '<i class="icon-terminal"></i> Terminal'
|
|
: '<i class="icon-screen"></i> Screen';
|
|
|
|
const connectButton = agent.online
|
|
? `<button onclick="connectToAgent('${agent.id}', ${agent.terminal_mode})">Connect</button>`
|
|
: '<span>Offline</span>';
|
|
|
|
return `<tr>
|
|
<td>${agent.name}</td>
|
|
<td>${icon}</td>
|
|
<td>${agent.os} ${agent.os_version}</td>
|
|
<td>${connectButton}</td>
|
|
</tr>`;
|
|
}
|
|
|
|
function connectToAgent(agentId, terminalMode) {
|
|
if (terminalMode) {
|
|
window.open(`/viewer-terminal.html?session=${agentId}&token=${JWT}`, '_blank');
|
|
} else {
|
|
window.open(`/viewer.html?session=${agentId}&token=${JWT}`, '_blank');
|
|
}
|
|
}
|
|
```
|
|
|
|
### Database Schema
|
|
|
|
**Minor addition to `sessions` table:**
|
|
|
|
```sql
|
|
-- migrations/012_terminal_mode.sql
|
|
ALTER TABLE connect_sessions ADD COLUMN terminal_mode BOOLEAN DEFAULT FALSE;
|
|
|
|
-- Optional: separate table for terminal recordings
|
|
CREATE TABLE IF NOT EXISTS terminal_recordings (
|
|
id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
|
|
session_id UUID REFERENCES connect_sessions(id) ON DELETE CASCADE,
|
|
started_at TIMESTAMPTZ DEFAULT NOW(),
|
|
ended_at TIMESTAMPTZ,
|
|
recording_data BYTEA, -- asciicast JSON or raw PTY dump (compressed)
|
|
size_bytes BIGINT,
|
|
INDEX idx_terminal_recordings_session (session_id)
|
|
);
|
|
```
|
|
|
|
## Implementation Details
|
|
|
|
### Files to Create
|
|
|
|
**Agent (Linux-specific):**
|
|
- `agent/src/platform/linux/pty.rs` — PTY spawn, I/O, resize (openpty, fork, exec)
|
|
- `agent/src/platform/linux/headless.rs` — Headless detection logic
|
|
- `agent/src/session/terminal.rs` — Terminal session loop (PTY ↔ WebSocket)
|
|
|
|
**Server:**
|
|
- `server/src/relay/terminal.rs` — Terminal message routing (TerminalData/Input/Resize)
|
|
- `server/static/viewer-terminal.html` — xterm.js-based web terminal viewer
|
|
- `server/static/vendor/xterm/` — xterm.js library files (CDN or bundled)
|
|
- `server/migrations/012_terminal_mode.sql` — Schema update
|
|
|
|
**Protobuf:**
|
|
- `proto/guruconnect.proto` — Add TerminalData, TerminalInput, TerminalResize messages
|
|
|
|
**Dashboard:**
|
|
- `server/static/dashboard.js` — Detect `terminal_mode`, render terminal icon, route to terminal viewer
|
|
|
|
### Key Dependencies
|
|
|
|
```toml
|
|
# agent/Cargo.toml (Linux-specific)
|
|
[target.'cfg(target_os = "linux")'.dependencies]
|
|
libc = "0.2" # openpty, fork, exec, ioctl
|
|
nix = "0.27" # Safe wrappers for POSIX APIs
|
|
```
|
|
|
|
**xterm.js (web viewer):**
|
|
- Version: 5.3.0+ (latest stable)
|
|
- Addons: `xterm-addon-fit` (auto-resize)
|
|
- Delivery: CDN link or bundled in `server/static/vendor/xterm/`
|
|
|
|
## Security Considerations
|
|
|
|
### Shell Access Risk
|
|
|
|
- **Privilege escalation:** PTY spawns shell as the agent's user (typically `root` if agent runs as systemd service)
|
|
- **Mitigation 1:** Run agent as unprivileged user (`guruconnect` service user), use `sudo` for privileged commands
|
|
- **Mitigation 2:** Add `allowed_commands` whitelist (optional Phase 2 feature) — restrict to specific binaries
|
|
- **Mitigation 3:** Audit logging: record all terminal I/O for compliance review
|
|
|
|
### Authentication
|
|
|
|
**Same as GUI agents:**
|
|
- Support-code for ad-hoc sessions (6-digit, time-limited)
|
|
- Persistent agent key for managed servers (per-agent `cak_*` key from SPEC-004)
|
|
- Viewer JWT token required for WebSocket connection
|
|
|
|
### Session Recording (Compliance)
|
|
|
|
- **Optional toggle:** dashboard setting "Record terminal sessions" (default: ON for compliance)
|
|
- **Storage:** `terminal_recordings` table (BYTEA column, compressed)
|
|
- **Playback:** Admin dashboard can replay terminal sessions as asciicast (xterm.js built-in playback)
|
|
- **Retention:** configurable (default: 90 days, auto-purge older recordings)
|
|
|
|
### Input Sanitization
|
|
|
|
- **No sanitization needed:** PTY handles raw bytes; ANSI escape sequences are terminal-native
|
|
- **DoS risk:** Malicious viewer could spam resize events; rate-limit `TerminalResize` (max 10/sec)
|
|
|
|
## Testing Strategy
|
|
|
|
### Unit Tests
|
|
|
|
- PTY spawn/cleanup: verify `openpty()` success, shell exec, FD management
|
|
- Terminal I/O: mock PTY master FD, test read/write buffers
|
|
- Protobuf serialization: TerminalData/Input/Resize round-trip
|
|
|
|
### Integration Tests
|
|
|
|
- **Headless VM:** Ubuntu Server 22.04 minimal (no desktop packages)
|
|
- **Agent install:** `guruconnect` binary, systemd service, no X11 deps
|
|
- **Connect flow:** Dashboard → "Connect" → xterm.js viewer → type `ls`, verify output
|
|
- **Resize:** Browser window resize → PTY receives SIGWINCH → `htop` redraws correctly
|
|
- **Session cleanup:** Close viewer → PTY process exits gracefully
|
|
|
|
### Manual Testing Scenarios
|
|
|
|
1. **Basic shell interaction:**
|
|
- Connect to headless agent via dashboard
|
|
- Type `ls -la`, verify colorized output
|
|
- Run `vim test.txt`, verify cursor movement, editing, save/quit
|
|
- Run `htop`, verify full-screen TUI app renders correctly
|
|
|
|
2. **Terminal resize:**
|
|
- Start session at default 80x24
|
|
- Resize browser window to 120x40
|
|
- Run `tput cols; tput lines` → verify output matches
|
|
- Run `htop` → verify UI scales to new dimensions
|
|
|
|
3. **Multi-line output:**
|
|
- Run `dmesg | head -100` → verify scrollback works
|
|
- Run `journalctl -f` → verify live log streaming
|
|
|
|
4. **Session recording playback:**
|
|
- Perform session actions (ls, vim, htop)
|
|
- End session
|
|
- Admin dashboard → "View Recording" → verify asciicast playback
|
|
|
|
5. **Privilege escalation (sudo):**
|
|
- Agent runs as `guruconnect` user (non-root)
|
|
- Connect via terminal
|
|
- Run `sudo apt update` → enter sudo password → verify command executes
|
|
- Run `whoami` → verify shows `root` after sudo
|
|
|
|
### Performance
|
|
|
|
- **Latency target:** <100ms round-trip for input (same as GUI mode)
|
|
- **Bandwidth:** ~1-5 KB/sec for typical terminal I/O (much lower than screen capture)
|
|
- **Stress test:** Run `yes` command (infinite output) → verify relay doesn't OOM, rate-limit applied
|
|
|
|
## Effort Estimate & Dependencies
|
|
|
|
**Size:** Medium (4-6 weeks, 1 developer)
|
|
|
|
**Breakdown:**
|
|
- PTY implementation (Linux agent): 1.5 weeks
|
|
- Protobuf protocol updates: 0.5 weeks
|
|
- Relay server terminal routing: 1 week
|
|
- xterm.js web viewer integration: 1 week
|
|
- Dashboard terminal mode detection + routing: 0.5 weeks
|
|
- Session recording + playback: 1 week
|
|
- Testing, edge cases, systemd integration: 1 week
|
|
- Documentation: 0.5 weeks
|
|
|
|
**Dependencies:**
|
|
- **SPEC-010 Linux agent base** — PTY mode extends the Linux agent; can be implemented in parallel with SPEC-010's GUI capture
|
|
- **xterm.js library** — mature, well-tested (used by VS Code, Jupyter, many commercial products)
|
|
- **libc/nix crates** — standard Rust POSIX bindings
|
|
- **SPEC-004 per-agent keys** — already shipped for persistent agent auth
|
|
|
|
**Unblocks:**
|
|
- Server management use case (Linux VMs, containers, bare metal)
|
|
- SSH replacement with centralized audit logging
|
|
- Emergency recovery (single-user mode, systemd rescue shell)
|
|
- Container debugging (exec into running containers via GuruConnect)
|
|
|
|
## Open Questions
|
|
|
|
1. **Run agent as root or unprivileged user?** — Recommend unprivileged `guruconnect` service user + sudo whitelist. Security-sensitive orgs may require root; make configurable.
|
|
|
|
2. **Shell selection?** — v1: `$SHELL` env var → `/bin/bash` → `/bin/sh`. Phase 2: dashboard setting to override shell per agent (`/bin/zsh`, `/bin/fish`).
|
|
|
|
3. **Concurrent PTY sessions?** — v1: one PTY per agent connection (like SSH). Phase 2: tmux/screen integration for multi-viewer session sharing.
|
|
|
|
4. **Terminal recording format?** — Asciicast (JSON, industry standard, xterm.js playback support) vs. raw PTY dump (more compact, custom playback). Recommend asciicast for v1.
|
|
|
|
5. **Command whitelisting?** — Optional Phase 2 feature. v1 is unrestricted shell access (same as SSH). Add `allowed_commands` array to agent config if compliance requires it.
|
|
|
|
6. **Windows/macOS terminal mode?** — Defer. Windows Server typically uses RDP or SSH (OpenSSH built-in since Server 2019). macOS servers are rare. Linux headless servers are the primary use case.
|
|
|
|
7. **File upload/download via terminal?** — v1: use standard tools (`scp`, `rsync`, `wget`). Phase 2: integrate with SPEC (file transfer) for dashboard-native upload/download.
|
|
|
|
---
|
|
|
|
**Cross-references:**
|
|
- SPEC-010: Cross-platform agents (macOS/Linux GUI) — headless mode extends Linux agent with PTY alternative
|
|
- SPEC-004: Stable machine identity — headless agents use same deterministic `machine_uid` (`/etc/machine-id`)
|
|
- ADR-001: GuruConnect is standalone — headless mode doesn't require GuruRMM integration
|
|
- Future: File transfer spec (roadmap item) — will integrate with terminal mode for `scp`-like functionality
|