Re: [pve-devel] [PATCH manager v3] ui: vm console: autodetect novnc or xtermjs

[Friedrich Weber <f.weber@proxmox.com>]

On 25/02/2025 16:47, Aaron Lauterer wrote:
> Some users configure their VMs to use serial as their display. The big
> benefit is that in combination with the xtermjs remote console, copy &
> paste works a lot better than via novnc.

I agree that defaulting to xterm.js in the serial terminal case makes
for a better user experience.

Tested this with a VM with a serial port booting from the PVE ISO,
didn't notice any big issues. See below for some minor comments.

> While the console button in the top right allows to manually choose the
> console type, the Console in the main submenu of a VM does not.
> 
> This patch changes the behavior for VMs and will first fetch the VM
> config and if the display is set to "serialX", will set the console to
> xtermjs. Otherwise it will fall back to regular noVNC.
> 
> Since getting the VM config is an async API call, the code had to be
> restructured so we can do the actual loading of the console after the
> config has been fetched.
> Therefore we now have the 'loadConsole()' function which will be called
> when the UI item is activated and in the KVM case, after loading and
> handling the VM config. It is guarded by the 'activated' and
> 'configLoaded' variables.
> 
> Signed-off-by: Aaron Lauterer <a.lauterer@proxmox.com>
> ---
> Another thing that I noticed is that the property we use to decide if we
> enable xtermjs for VMs in the top right console button only checks if
> the VM has a serial device configured.
> PVE::QemuServer::vmstatus() calls `conf_has_serial()`.
> 
> A better approach would be to have a vmstatus property that actually
> tells us if the VM has serial set as display option. As the display
> could be set to something else, even if a serial device exists. There
> are other use-cases for a serial device in the VM, like passing through
> an actual serial port.
> But I did not want to introduce another new property for vmstatus() and
> changing the meaning of the current serial property would be a breaking
> change.
> Therefore, this current UI only implementation.
> 
> changes since:
> v2:
> * change approach and do it in the UI alone by fetching the VM
>   config before deciding which console to use
> 
> v1:
> * set 'autodetect' to always true in 'VNCConsole.js'
> * add additional checks in pveproxy
>   * only if autodetect is enabled and console is set to 'kvm'
>   * username exists and has VM.Console permissions for the guest
> 
>  www/manager6/VNCConsole.js | 61 +++++++++++++++++++++++++++-----------
>  1 file changed, 44 insertions(+), 17 deletions(-)
> 
> diff --git a/www/manager6/VNCConsole.js b/www/manager6/VNCConsole.js
> index 9057e447..69ced0f8 100644
> --- a/www/manager6/VNCConsole.js
> +++ b/www/manager6/VNCConsole.js
> @@ -27,31 +27,58 @@ Ext.define('PVE.noVncConsole', {
>  	    throw "no VM ID specified";
>  	}
>  
> +	let activated = false;
> +	let configLoaded = false;
>  	// always use same iframe, to avoid running several noVnc clients
>  	// at same time (to avoid performance problems)
>  	var box = Ext.create('Ext.ux.IFrame', { itemid: "vncconsole" });
>  
> -	var type = me.xtermjs ? 'xtermjs' : 'novnc';
> +	let loadConsole = function() {
> +	    if (!activated || !configLoaded) {
> +		return;
> +	    }

I was wondering whether there might a race condition possible here
(i.e., the success callback of API2Request and the `activate` listener
called with unfortunate timing that would prevent the console from
appearing), but thinking about it more, it looks okay -- there is no
threading and both the callback and the listener should normally be
called eventually (in whatever order). We won't get a console if the
/config API request fails, but I guess in that case something is
currently wrong with the setup anyway.

> +	    let type = me.xtermjs ? 'xtermjs' : 'novnc';
> +	    let sp = Ext.state.Manager.getProvider();
> +	    if (Ext.isFunction(me.beforeLoad)) {
> +		me.beforeLoad();
> +	    }
> +	    let queryDict = {
> +		console: me.consoleType, // kvm, lxc, upgrade or shell
> +		vmid: me.vmid,
> +		node: me.nodename,
> +		cmd: me.cmd,
> +		'cmd-opts': me.cmdOpts,
> +		resize: sp.get('novnc-scaling', 'scale'),
> +	    };
> +	    queryDict[type] = 1;
> +	    PVE.Utils.cleanEmptyObjectKeys(queryDict);
> +	    var url = '/?' + Ext.Object.toQueryString(queryDict);
> +	    box.load(url);
> +	};
> +
> +	if (me.consoleType ==="kvm") {

nit: missing space after the ===

> +	    Proxmox.Utils.API2Request({
> +		url: `/api2/extjs/nodes/${me.nodename}/qemu/${me.vmid}/config`,

Stumbled upon this by accident: I guess this could should pass
`current=1` to get the currently running config instead of the config
with pending changes applied (because the running config one is the
relevant one for deciding whether to use noVNC or xterm.js).

> +		method: 'GET',
> +		failure: response => Ext.Msg.alert('Error', response.htmlStatus),
> +		success: function({ result }, options) {
> +		    if (result.data.vga?.startsWith("serial")) {
> +			me.xtermjs = true;
> +		    }
> +		    configLoaded = true;
> +		    loadConsole();
> +		},
> +	    });
> +	} else { // don't need to load anything else
> +	    configLoaded = true;
> +	}
> +
>  	Ext.apply(me, {
>  	    items: box,
>  	    listeners: {
>  		activate: function() {
> -		    let sp = Ext.state.Manager.getProvider();
> -		    if (Ext.isFunction(me.beforeLoad)) {
> -			me.beforeLoad();
> -		    }
> -		    let queryDict = {
> -			console: me.consoleType, // kvm, lxc, upgrade or shell
> -			vmid: me.vmid,
> -			node: me.nodename,
> -			cmd: me.cmd,
> -			'cmd-opts': me.cmdOpts,
> -			resize: sp.get('novnc-scaling', 'scale'),
> -		    };
> -		    queryDict[type] = 1;
> -		    PVE.Utils.cleanEmptyObjectKeys(queryDict);
> -		    var url = '/?' + Ext.Object.toQueryString(queryDict);
> -		    box.load(url);
> +		    activated = true;
> +		    loadConsole();
>  		},
>  	    },
>  	});



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