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RFD 189: Console Access - vmadmd console proxy #1159

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RFD 189: Console Access - vmadmd console proxy #1159

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fd44461
Add console proxy support to vmadmd
nwilkens Sep 30, 2025
b4a61eb
Add console to runtime_info for all VM brands
nwilkens Sep 30, 2025
f6b4547
Spawn console proxy for all running VMs at startup
nwilkens Sep 30, 2025
c09edc8
Fix console proxy to use fs streams for device files
nwilkens Oct 1, 2025
dda998b
Use socat to proxy zone console devices
nwilkens Oct 1, 2025
44a60a8
Use zoneadmd console socket instead of /dev/zcons device
nwilkens Oct 1, 2025
abfe095
Add zoneadmd console handshake for non-KVM brands
nwilkens Oct 1, 2025
44e65b8
Fix resource leaks and add handshake timeout in console proxy
nwilkens Oct 1, 2025
5e564d5
Add named constants and improve protocol validation
nwilkens Jan 12, 2026
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9 changes: 6 additions & 3 deletions src/vm/node_modules/proptable.js
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224 changes: 224 additions & 0 deletions src/vm/sbin/vmadmd.js
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Original file line number Diff line number Diff line change
Expand Up @@ -63,6 +63,11 @@ var REPORTED_STATES = ['running', 'stopped'];
var VMADMD_PORT = 8080;
var VMADMD_AUTOBOOT_FILE = '/tmp/.autoboot_vmadmd';

// Console proxy configuration
var CONSOLE_HANDSHAKE_TIMEOUT = 5000; // Timeout for zoneadmd handshake (ms)
var CONSOLE_LOG_TRUNCATE_LEN = 100; // Max chars to log from handshake errors

var CONSOLE = {};
var PROV_WAIT = {};
var SDC = {};
var SPICE = {};
Expand Down Expand Up @@ -411,6 +416,186 @@ function reloadRemoteDisplay(vmobj)
spawnRemoteDisplay(vmobj);
}

//
// spawnConsoleProxy()
//
// Creates a TCP proxy for console access (serial console for KVM, zone console
// for other brands).
//
// For KVM: Proxies to unix socket at <zonepath>/root/tmp/vm.console
// For other brands: Proxies to zone console device at /dev/zcons/<zonename>/zoneconsole
//
// vmobj must have:
//
// brand
// state
// uuid
// zonename
// zonepath
// zone_state
//
function spawnConsoleProxy(vmobj)
{
var addr;
var consolePath;
var port = 0; // Let the OS assign an ephemeral port
var server;
var zonepath = vmobj.zonepath;

if (!vmobj.zonepath) {
zonepath = '/zones/' + vmobj.uuid;
}

if (vmobj.state !== 'running' && vmobj.zone_state !== 'running') {
log.debug('skipping console setup for non-running VM ' + vmobj.uuid);
return;
}

// Determine console path based on brand
if (vmobj.brand === 'kvm') {
// KVM uses unix socket for serial console
consolePath = path.join(zonepath, '/root/tmp/vm.console');
} else {
// Bhyve, Joyent, LX, etc. use zoneadmd console socket
consolePath = '/var/run/zones/' + vmobj.zonename + '.console_sock';
}

// Create TCP server that proxies to console socket
server = net.createServer(function (c) {
var consoleSocket = new net.Socket();
var remote_address = '';
var isKvm = (vmobj.brand === 'kvm');
var handshakeDone = false;
var handshakeTimer = null;
var cleanedUp = false;

remote_address = '[' + c.remoteAddress + ']:' + c.remotePort;

// Cleanup function ensures all resources are properly released
function cleanup() {
if (cleanedUp) {
return;
}
cleanedUp = true;

if (handshakeTimer) {
clearTimeout(handshakeTimer);
handshakeTimer = null;
}

if (consoleSocket && !consoleSocket.destroyed) {
consoleSocket.destroy();
}
}

c.on('close', function (had_error) {
log.info('console connection ended from ' + remote_address +
' for VM ' + vmobj.uuid);
cleanup();
});

consoleSocket.on('error', function (err) {
log.warn('console socket error for VM ' + vmobj.uuid +
': ' + err.message);
cleanup();
c.end();
});

c.on('error', function (err) {
log.warn('console net socket error for VM ' + vmobj.uuid +
': ' + err.message);
cleanup();
});

// For non-KVM brands, perform zoneadmd console handshake
if (!isKvm) {
// Set timeout for handshake completion
handshakeTimer = setTimeout(function() {
if (!handshakeDone) {
log.error('console handshake timeout for VM ' + vmobj.uuid);
cleanup();
c.end();
}
}, CONSOLE_HANDSHAKE_TIMEOUT);

consoleSocket.once('connect', function () {
// Send zlogin-C handshake: IDENT <locale> <flags>\n
consoleSocket.write('IDENT C 0\n');

// Wait for OK response before starting data flow
consoleSocket.once('data', function (data) {
clearTimeout(handshakeTimer);
handshakeTimer = null;

if (data.toString().trim() === 'OK') {
handshakeDone = true;
// Now start bidirectional pipe
c.pipe(consoleSocket);
consoleSocket.pipe(c);
} else {
log.error('console handshake failed for VM ' + vmobj.uuid +
': ' + data.toString().substring(0, CONSOLE_LOG_TRUNCATE_LEN));
cleanup();
c.end();
}
});
});
} else {
// KVM brand: pipe immediately (no handshake needed)
handshakeDone = true;
c.pipe(consoleSocket);
consoleSocket.pipe(c);
}

// Connect to console socket
consoleSocket.connect(consolePath);
});

log.info('spawning console listener for ' + vmobj.uuid +
' on ' + SDC.sysinfo.admin_ip + ' (brand: ' + vmobj.brand + ')');

server.on('connection', function (sock) {
log.info('console connection started from [' +
sock.remoteAddress + ']:' + sock.remotePort + ' for VM ' + vmobj.uuid);
});

server.on('error', function (err) {
log.error('console server error for VM ' + vmobj.uuid + ': ' + err.message);
});

server.listen(port, SDC.sysinfo.admin_ip, function () {
addr = server.address();

CONSOLE[vmobj.uuid] = {
'host': SDC.sysinfo.admin_ip,
'port': addr.port,
'server': server,
'type': 'socket',
'path': consolePath
};
Comment on lines +566 to +575

Copilot AI Oct 8, 2025

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The CONSOLE object is being populated inside the async callback, but the function returns immediately without waiting for the server to start listening. This creates a race condition where other code trying to access CONSOLE[vmobj.uuid] might find it undefined.

Copilot uses AI. Check for mistakes.

@danmcd danmcd Oct 8, 2025

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A JS person should reality-check this.

@danmcd danmcd Jan 12, 2026

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When this moves to non-draft we'll need >= two reviewers for JS reality checking.


log.info('console proxy for ' + vmobj.uuid + ' listening on ' +
SDC.sysinfo.admin_ip + ':' + addr.port +
' (type: ' + CONSOLE[vmobj.uuid].type + ', path: ' + consolePath + ')');
});
}

function clearConsoleProxy(uuid)
{
if (CONSOLE[uuid] && CONSOLE[uuid].server) {
log.info('clearing console proxy for ' + uuid);
CONSOLE[uuid].server.close();
}
delete CONSOLE[uuid];
}

function reloadConsoleProxy(vmobj)
{
log.info('reloading console proxy for ' + vmobj.uuid);
clearConsoleProxy(vmobj.uuid);
spawnConsoleProxy(vmobj);
}

function clearTimer(uuid)
{
if (TIMER.hasOwnProperty(uuid)) {
Expand All @@ -422,6 +607,7 @@ function clearTimer(uuid)
function clearVM(uuid)
{
clearRemoteDisplay(uuid);
clearConsoleProxy(uuid);
clearTimer(uuid);
}

Expand Down Expand Up @@ -516,6 +702,7 @@ function handleProvisioning(vmobj, cb)
rotateKVMLog(vmobj.uuid);
}
spawnRemoteDisplay(obj);
spawnConsoleProxy(obj);
}
cb(null, 'success');
});
Expand Down Expand Up @@ -1139,6 +1326,7 @@ function updateZoneStatus(ev)
rotateKVMLog(vmobj.uuid);
}
spawnRemoteDisplay(vmobj);
spawnConsoleProxy(vmobj);
} else if (ev.oldstate === 'running') {
if (VNC.hasOwnProperty(ev.zonename)) {
// VMs always have zonename === uuid, so we can remove this
Expand Down Expand Up @@ -1567,6 +1755,11 @@ function infoVM(uuid, types, callback)
}
}
}
if ((types.indexOf('all') !== -1)
|| (types.indexOf('console') !== -1)) {

infoConsole();
}
callback(null, res);
}
});
Expand All @@ -1580,9 +1773,24 @@ function infoVM(uuid, types, callback)
if (types.indexOf('all') !== -1 || types.indexOf('vnc') !== -1) {
infoVNC();
}
if (types.indexOf('all') !== -1 || types.indexOf('console') !== -1) {
infoConsole();
}
callback(null, res);
};

// Generic callback for other brands (joyent, lx, etc.) - only console info
loadCbs.joyent = loadCbs['joyent-minimal'] = loadCbs.lx =
function loadGenericCb(vmobj) {
assert.object(vmobj);
assert.uuid(vmobj.uuid);

if (types.indexOf('all') !== -1 || types.indexOf('console') !== -1) {
infoConsole();
}
callback(null, res);
};

function infoVNC() {
res.vnc = {};
if (VNC.hasOwnProperty(uuid)) {
Expand All @@ -1598,6 +1806,15 @@ function infoVM(uuid, types, callback)
}
}
}

function infoConsole() {
res.console = {};
if (CONSOLE.hasOwnProperty(uuid)) {
res.console.host = CONSOLE[uuid].host;
res.console.port = CONSOLE[uuid].port;
res.console.type = CONSOLE[uuid].type;
}
}
}

function resetVM(uuid, callback)
Expand Down Expand Up @@ -1831,6 +2048,9 @@ function loadVM(vmobj, do_autoboot)

// Start Remote Display
spawnRemoteDisplay(vmobj);

// Start Console Proxy

@danmcd danmcd Jan 12, 2026

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This and other always-on calls to spawnRemoteDisplay() have me curious about an overarching question. Will ask it in the overarching comment.

spawnConsoleProxy(vmobj);
}

// To help diagnose problems we write the keys we're watching to the TRACE log
Expand Down Expand Up @@ -2528,6 +2748,10 @@ function main()
});
} else {
log.debug('ignoring non-kvm VM ' + vmobj.uuid);
// Still spawn console proxy for non-KVM running VMs
if (vmobj.state === 'running' || vmobj.zone_state === 'running') {
spawnConsoleProxy(vmobj);
}
upg_cb();
}
}
Expand Down