What does @jkreidl have to say about bootstrapping an HVM guest using only XAPI on the CLI?

Eric P.
Reno, Nevada

@livierlambert said in Creating a VM using only the XAPI CLI...:

You'll need a better client to do that.

I don't understand. Would you please elaborate?

TIA,
Eric P.
Reno, Nevada

@livierlambert Is there any way to bootstrap an HVM guest using only XAPI on the CLI?

TIA,
Eric P.
Reno, Nevada

If it's possible to over-subscribe vCPU's: What do vCPU's really represent - A weighted average of CPU cycles that will be allocated to the guest?

e.g., If a host has eight CPU cores with hyperthreading enabled and all four guests are allocated 16 vCPU's: What benefit will the four guests see over what they would experience if they had each been allocated 2 vCPU's?

TIA,
Eric Pretorious
Reno, Nevada

@livierlambert Thanks. But I'm not looking for the most current method of installing a guest - I'm looking for the simplest method of installing a guest using XAPI on the command-line interface (CLI).

The "Citrix XenServer 7.2 Virtual Machine User's Guide" includes a method to do that using the CLI:

xe vm-install template=<template> new-name-label=<name_for_vm> sr-uuid=<storage_repository_uuid>

xe vif-create vm-uuid=<vm_uuid> network-uuid=<network_uuid> mac=random device=0

xe vm-param-set uuid=<vm_uuid> other-config:install-repository=<network_repository>

xe vm-start uuid=<vm_uuid>

But obviously it's missing something!

Have you got any suggestions about what might be missing from those four simple steps?

TIA,
Eric P.
Reno, Nevada

@livierlambert I don't understand. Would you please elaborate?

TIA,
Eric P.
Reno, Nevada

@livierlambert

• It's a CentOS-7 HVM guest.
• What are these hidden files that you are referring to?

FWIW: These are the contents of the remote package repository (nfs://192.168.0.95/srv/pkgs/ISO)

# mount -t nfs 192.168.0.95:/srv/pkgs/ISO /mnt

# ll /mnt
total 110
-rw-rw-r-- 1 root root    14 Sep  9  2019 CentOS_BuildTag
drwxr-xr-x 3 root root  2048 Sep  6  2019 EFI
-rw-rw-r-- 1 root root   227 Aug 30  2017 EULA
-rw-rw-r-- 1 root root 18009 Dec  9  2015 GPL
drwxr-xr-x 3 root root  2048 Sep  9  2019 images
drwxr-xr-x 2 root root  2048 Sep  9  2019 isolinux
drwxr-xr-x 2 root root  2048 Sep  6  2019 LiveOS
drwxrwxr-x 2 root root 73728 Sep 11  2019 Packages
drwxrwxr-x 2 root root  4096 Sep 11  2019 repodata
-rw-rw-r-- 1 root root  1690 Dec  9  2015 RPM-GPG-KEY-CentOS-7
-rw-rw-r-- 1 root root  1690 Dec  9  2015 RPM-GPG-KEY-CentOS-Testing-7
-r--r--r-- 1 root root  2883 Sep 11  2019 TRANS.TBL

HTH,
Eric P.
Reno, Nevada

FWIW: The result seems to be the same whether I use an ISO image on a remote NFS server (nfs://192.168.0.95/srv/images/ISO/CentOS-7.7-x86_64-Minimal.iso) or I use a remote package repository (nfs://192.168.0.95/srv/pkgs/ISO) for installation:

# VM_UUID=$(xe vm-install template=CentOS\ 7 new-name-label=CentOS7-2)
# echo $VM_UUID
c9c66b15-e618-dc12-0f93-8e39af102c8b

# VIF_UUID=$(xe vif-create mac=random device=0 vm-uuid=$VM_UUID network-uuid=$NET_UUID)
# echo $VIF_UUID
de6b51ec-54ed-fa0c-0ba2-7da732e8fa05

# xe vm-param-set uuid=$VM_UUID other-config:install-repository=nfs://192.168.0.95/srv/pkgs/ISO

# xe vm-start uuid=$VM_UUID

# xe console uuid=$VM_UUID
No text console available

# xe vm-param-list uuid=$VM_UUID | grep dom-id
                                dom-id ( RO): 8

# xenstore-ls /local/domain/8
xenstore-ls: xs_directory (/local/domain/8): No such file or directory

What am I doing wrong?

TIA,
Eric P.
Reno, Nevada

I'm attempting to create a CentOS-7 VM from the CLI using modified instructions from the "Citrix XenServer 7.2 Virtual Machine User's Guide":

# NET_UUID=$(xe network-list bridge=xenbr0 params=uuid | awk '{ print $5 }')
# echo $NET_UUID
47a6223e-74d0-b75d-bec3-0ca6324b498c

# VM_UUID=$(xe vm-install template=CentOS\ 7 new-name-label=CentOS7-1)
# echo $VM_UUID
26859adf-f2f9-77d6-3f3c-719ecd885535

# VIF_UUID=$(xe vif-create mac=random device=0 vm-uuid=$VM_UUID network-uuid=$NET_UUID)
# echo $VIF_UUID
decb158e-2961-7448-8b7c-4c2707298604

# xe vm-param-set uuid=$VM_UUID other-config:install-repository=nfs://192.168.0.95/srv/images/ISO/CentOS-7.7-x86_64-Minimal.iso
# xe vm-start uuid=$VM_UUID

But when I use the console command in order to complete the installation of the operating system: I get this...

# xe console uuid=$VM_UUID
No text console available

And when I search Xenstore for the VNC-port information I get this:

# xe vm-param-list uuid=$VM_UUID | grep dom-id
                                dom-id ( RO): -1

What have I done wrong? How can I determine the root cause of the failure?

TIA,
Eric Pretorious
Reno, Nevada

What's the purpose of this other VNC daemon on TCP/9500?

From the Xen Project wiki page on XCP:

The ports used for VNC console are 5901-5999, and the ports used for text console are 9501-9599.

AFAICT: TCP/5900 & TCP/9500 belong to Dom0...

# xenstore-ls /local/domain/0
control = ""
 feature-poweroff = "1"
 feature-reboot = "1"
 feature-suspend = "1"
domid = "0"
name = "Domain-0"
vncterm-pid = "1276"
console = ""
 vnc-port = "5900"
 tc-port = "9500"
vm = "/vm/7a4488c6-d4ac-4aaf-83f0-fb6d3f557f48"

But I don't know how to connect to DomU #1's console because there is no entry in Xenstore for DomU #1:

# xenstore-ls /local/domain/1
xenstore-ls: xs_directory (/local/domain/1): No such file or directory

Ideas? Suggestions?

Eric P.
Reno, Nevada

FWIW: I did notice that there was more than one TCP port connected to the VNC server:

# netstat -tanp | grep vnc
tcp        0      0 127.0.0.1:5900          0.0.0.0:*               LISTEN      1276/vncterm        
tcp        0      0 127.0.0.1:9500          0.0.0.0:*               LISTEN      1276/vncterm

So I also connected to the TCP/9500 port:

$ ssh -L 9500:localhost:9500 root@192.168.0.92
root@192.168.0.92's password: 
Last login: Tue Nov  1 01:14:11 2022

# xe vm-list name-label=CentOS7-1 
uuid ( RO)           : 2f343ae1-0d57-ef21-6a54-6abe7b7264c6
     name-label ( RW): CentOS7-1
    power-state ( RO): running

# xe vm-list name-label=CentOS7-1 params=dom-id
dom-id ( RO)    : 1

But nothing ever happened! i.e., The VNC client failed to open a window on my local system.

What's the purpose of this other VNC daemon on TCP/9500?

TIA,
Eric P.
Reno, Nevada

@livierlambert Yes - I authenticated as the root user. But after that there was nothing - Only a terminal session like a standard SSH session!

Ideas? Suggestions?

Eric P.
Reno, Nevada

I think that this wiki page from the Xen Project may provide the answer:

• Use SSH to tunnel localhost:5900 to TCP/5900 of the host system. And then
• Use a VNC client to access localhost:5900.

I've already confirmed that the host is listening on TCP/5900:

# netstat -tanp | grep \:59
tcp        0      0 127.0.0.1:5900          0.0.0.0:*               LISTEN      1276/vncterm

So I configured the tunnel:

$ ssh -L 5900:localhost:5900 root@192.168.0.92
root@192.168.0.92's password: 
Last login: Tue Nov  1 01:10:30 2022

# xe vm-list name-label=CentOS7-1 
uuid ( RO)           : 2f343ae1-0d57-ef21-6a54-6abe7b7264c6
     name-label ( RW): CentOS7-1
    power-state ( RO): running

# xe vm-list name-label=CentOS7-1 params=dom-id
dom-id ( RO)    : 1

And then I launched the client and connected to localhost:5900:

$ vncviewer 

TigerVNC Viewer 64-bit v1.12.0
Built on: 2022-03-25 17:06
Copyright (C) 1999-2021 TigerVNC Team and many others (see README.rst)
See https://www.tigervnc.org for information on TigerVNC.

Mon Oct 31 18:18:08 2022
 DecodeManager: Detected 8 CPU core(s)
 DecodeManager: Creating 4 decoder thread(s)
 CConn:       Connected to host localhost port 5900
 CConnection: Server supports RFB protocol version 3.3
 CConnection: Using RFB protocol version 3.3
 CConn:       Using pixel format depth 24 (32bpp) little-endian rgb888

A connection is established:

# netstat -tanp | grep \:59
tcp        0      0 127.0.0.1:5900          0.0.0.0:*               LISTEN      1276/vncterm        
tcp        0      0 127.0.0.1:34046         127.0.0.1:5900          ESTABLISHED 18949/sshd: root@pt 
tcp        0      0 127.0.0.1:5900          127.0.0.1:34046         ESTABLISHED 1276/vncterm        

But the display seems to be a text console on the host system!

Have I misunderstood some detail?

Eric P.
Reno, Nevada

@livierlambert Thanks!

Using only the CLI: How can I connect VNC to the guest in order to complete the installation? e.g., xe console-list vm-name-label=<<<your_vm>>> lists an HTTP URL for connecting to the host...

# xe console-list vm-name-label=CentOS7-1 
uuid ( RO)             : fd376ea3-a644-2ed3-2d72-8ae7ca7a6b71
          vm-uuid ( RO): 2f343ae1-0d57-ef21-6a54-6abe7b7264c6
    vm-name-label ( RO): CentOS7-1
         protocol ( RO): RFB
         location ( RO): https://192.168.0.93/console?uuid=fd376ea3-a644-2ed3-2d72-8ae7ca7a6b71

But it doesn't seem to do anything!

TIA,
Eric P.
Reno, Nevada

@livierlambert Thanks for asking! My goal is to manually create a single CentOS VM so that I can get a better understanding all of the complicated details that XO hides from XCP-ng/XenServer administrators.

@livierlambert I'm just wanting to create a CentOS VM using the CLI.

@livierlambert Is there a command for connecting VNC to the VM's console?

I'm attempting to create a CentOS-7 VM from the CLI using the instructions from the "Citrix XenServer 7.2 Virtual Machine User's Guide":

# xe network-list | grep -B1 eth0
uuid ( RO)                : 47a6223e-74d0-b75d-bec3-0ca6324b498c
          name-label ( RW): Pool-wide network associated with eth0

# xe pool-param-list uuid=e3cdb4f9-6589-2ac2-f08a-9318a8a48a61 | grep default-SR
default-SR ( RW): 21044441-dfba-9293-408b-41379e194718

# xe vm-install template=Red\ Hat\ Enterprise\ Linux\ 7 new-name-label=CentOS7-1 sr-uuid=21044441-dfba-9293-408b-41379e194718 
2f343ae1-0d57-ef21-6a54-6abe7b7264c6

# xe vif-create vm-uuid=2f343ae1-0d57-ef21-6a54-6abe7b7264c6 network-uuid=47a6223e-74d0-b75d-bec3-0ca6324b498c mac=random device=0
f21d558a-c9ba-bb65-d2bc-6c2310d4a0cf

# xe vm-param-set uuid=2f343ae1-0d57-ef21-6a54-6abe7b7264c6 other-config:install-repository=nfs://192.168.0.95/srv/images/ISO/CentOS-7.7-x86_64-Minimal.iso

# xe vm-start uuid=2f343ae1-0d57-ef21-6a54-6abe7b7264c6

But when I start the VM: XAPI complains No text console available

# xe console vm=CentOS7-1
No text console available

# xe vm-list | grep -A1 -B1 CentOS
uuid ( RO)           : 2f343ae1-0d57-ef21-6a54-6abe7b7264c6
     name-label ( RW): CentOS7-1
    power-state ( RO): running

What am I doing wrong?

TIA,
Eric Pretorious
Reno, Nevada

@livierlambert Refreshing the status log and updating a second time retrieves/installs more updates.

After that: The '+ New' menu button appears in the menu on the left side of the window!

Thank you!

Eric P.
Reno, Nevada