[pve-devel] [PATCH qemu-server] vm_start: add syslog info with which PID a VM was started

[pve-devel] [PATCH qemu-server] vm_start: add syslog info with which PID a VM was started

[Daniel Kral]

Adds a syslog entry to log the process id that has been given to the
QEMU VM process at start. This is helpful debugging information if the
pid shows up at other places, like a kernel stack trace, while the VM
has been running, but cannot be retrieved anymore (e.g. the pidfile has
been deleted or only the syslog is available).

The syslog has been put in the `PVE::QemuServer::vm_start_nolock`
subroutine to make sure that the PID is logged not only when the VM has
been started by the API endpoint `vm_start`, but also when the VM is
started by a remote migration.

Signed-off-by: Daniel Kral <d.kral@proxmox.com>
Suggested-by: Hannes Dürr <h.duerr@proxmox.com>
Suggested-by: Friedrich Weber <f.weber@proxmox.com>
---
 PVE/QemuServer.pm | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/PVE/QemuServer.pm b/PVE/QemuServer.pm
index b26da505..d998b360 100644
--- a/PVE/QemuServer.pm
+++ b/PVE/QemuServer.pm
@@ -43,6 +43,7 @@ use PVE::ProcFSTools;
 use PVE::PBSClient;
 use PVE::RESTEnvironment qw(log_warn);
 use PVE::RPCEnvironment;
+use PVE::SafeSyslog;
 use PVE::Storage;
 use PVE::SysFSTools;
 use PVE::Systemd;
@@ -5971,6 +5972,8 @@ sub vm_start_nolock {
     eval { PVE::QemuServer::PCI::reserve_pci_usage($pci_reserve_list, $vmid, undef, $pid) };
     warn $@ if $@;
 
+    syslog("info", "VM $vmid started with pid $pid.");
+
     if (defined(my $migrate = $res->{migrate})) {
 	if ($migrate->{proto} eq 'tcp') {
 	    my $nodename = nodename();
-- 
2.39.5



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Re: [pve-devel] [PATCH qemu-server] vm_start: add syslog info with which PID a VM was started

[Fiona Ebner]

Am 26.09.24 um 10:36 schrieb Daniel Kral:
> Adds a syslog entry to log the process id that has been given to the
> QEMU VM process at start. This is helpful debugging information if the
> pid shows up at other places, like a kernel stack trace, while the VM
> has been running, but cannot be retrieved anymore (e.g. the pidfile has
> been deleted or only the syslog is available).
> 
> The syslog has been put in the `PVE::QemuServer::vm_start_nolock`
> subroutine to make sure that the PID is logged not only when the VM has
> been started by the API endpoint `vm_start`, but also when the VM is
> started by a remote migration.
> 
> Signed-off-by: Daniel Kral <d.kral@proxmox.com>
> Suggested-by: Hannes Dürr <h.duerr@proxmox.com>
> Suggested-by: Friedrich Weber <f.weber@proxmox.com>

Nit: the Signed-off-by trailer should come after the Suggested-by
trailers, because it was the last thing that happened chronologically
(the change was first suggested, then you wrote it ;)).

With the nits addressed:

Reviewed-by: Fiona Ebner <f.ebner@proxmox.com>

> ---
>  PVE/QemuServer.pm | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/PVE/QemuServer.pm b/PVE/QemuServer.pm
> index b26da505..d998b360 100644
> --- a/PVE/QemuServer.pm
> +++ b/PVE/QemuServer.pm
> @@ -43,6 +43,7 @@ use PVE::ProcFSTools;
>  use PVE::PBSClient;
>  use PVE::RESTEnvironment qw(log_warn);
>  use PVE::RPCEnvironment;
> +use PVE::SafeSyslog;
>  use PVE::Storage;
>  use PVE::SysFSTools;
>  use PVE::Systemd;
> @@ -5971,6 +5972,8 @@ sub vm_start_nolock {
>      eval { PVE::QemuServer::PCI::reserve_pci_usage($pci_reserve_list, $vmid, undef, $pid) };
>      warn $@ if $@;
>  
> +    syslog("info", "VM $vmid started with pid $pid.");

Nit: I'd capitalize "PID"

> +
>      if (defined(my $migrate = $res->{migrate})) {
>  	if ($migrate->{proto} eq 'tcp') {
>  	    my $nodename = nodename();


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Re: [pve-devel] [PATCH qemu-server] vm_start: add syslog info with which PID a VM was started

[Daniel Kral]

On 10/22/24 13:13, Fiona Ebner wrote:
> Am 26.09.24 um 10:36 schrieb Daniel Kral:
>> Adds a syslog entry to log the process id that has been given to the
>> QEMU VM process at start. This is helpful debugging information if the
>> pid shows up at other places, like a kernel stack trace, while the VM
>> has been running, but cannot be retrieved anymore (e.g. the pidfile has
>> been deleted or only the syslog is available).
>>
>> The syslog has been put in the `PVE::QemuServer::vm_start_nolock`
>> subroutine to make sure that the PID is logged not only when the VM has
>> been started by the API endpoint `vm_start`, but also when the VM is
>> started by a remote migration.
>>
>> Signed-off-by: Daniel Kral <d.kral@proxmox.com>
>> Suggested-by: Hannes Dürr <h.duerr@proxmox.com>
>> Suggested-by: Friedrich Weber <f.weber@proxmox.com>
> 
> Nit: the Signed-off-by trailer should come after the Suggested-by
> trailers, because it was the last thing that happened chronologically
> (the change was first suggested, then you wrote it ;)).

Thanks for the clarification, makes sense and will keep that in mind in 
future cases for sure :).

> 
> With the nits addressed:
> 
> Reviewed-by: Fiona Ebner <f.ebner@proxmox.com>
> 
>> ---
>>   PVE/QemuServer.pm | 3 +++
>>   1 file changed, 3 insertions(+)
>>
>> diff --git a/PVE/QemuServer.pm b/PVE/QemuServer.pm
>> index b26da505..d998b360 100644
>> --- a/PVE/QemuServer.pm
>> +++ b/PVE/QemuServer.pm
>> @@ -43,6 +43,7 @@ use PVE::ProcFSTools;
>>   use PVE::PBSClient;
>>   use PVE::RESTEnvironment qw(log_warn);
>>   use PVE::RPCEnvironment;
>> +use PVE::SafeSyslog;
>>   use PVE::Storage;
>>   use PVE::SysFSTools;
>>   use PVE::Systemd;
>> @@ -5971,6 +5972,8 @@ sub vm_start_nolock {
>>       eval { PVE::QemuServer::PCI::reserve_pci_usage($pci_reserve_list, $vmid, undef, $pid) };
>>       warn $@ if $@;
>>   
>> +    syslog("info", "VM $vmid started with pid $pid.");
> 
> Nit: I'd capitalize "PID"
> 
>> +
>>       if (defined(my $migrate = $res->{migrate})) {
>>   	if ($migrate->{proto} eq 'tcp') {
>>   	    my $nodename = nodename();

Sent a v2 with both changes [0].

[0] 
https://lore.proxmox.com/pve-devel/20241023095543.57202-1-d.kral@proxmox.com/


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