CP-54476 Merge ntp disable/enable to ntp mode #6765

changlei-li · 2025-11-25T07:04:48Z

As the doc PR #6745 shows, the enable/disable ntp APIs and host.ntp_enabled field can be merged into host.ntp_mode.
Now, the ntp modes are DHCP, Custom, Factory and Disabled.
This PR also updates the datamodel lifecycle and bumps up the schema.

changlei-li · 2025-11-25T07:14:06Z

Test:

    # set NTP mode Custom, use custom NTP servers
    session.xenapi.host.set_ntp_custom_servers(host_ref, ['time.google.com', 'time.windows.com', 'time.apple.com'])
    session.xenapi.host.set_ntp_mode(host_ref, 'Custom')
    time.sleep(5)
    show('NTP mode Custom, use custom NTP servers')

    # set NTP mode DHCP
    session.xenapi.host.set_ntp_mode(host_ref, 'DHCP')
    time.sleep(5)
    show('set NTP mode DHCP')

    # set NTP mode Factory
    session.xenapi.host.set_ntp_mode(host_ref, 'Factory')
    time.sleep(5)
    show('set NTP mode Factory')

    # disable NTP
    session.xenapi.host.set_ntp_mode(host_ref, 'Disabled')
    session.xenapi.host.set_servertime(host_ref, '20251125T14:11:55+08:00')
    show('set NTP mode Disbaled and set server time')

    # enable NTP and set to DHCP mode
    session.xenapi.host.set_ntp_mode(host_ref, 'DHCP')
    time.sleep(5)
    show('set NTP mode DHCP')

output:

===NTP mode Custom, use custom NTP servers===
ntp_mode: Custom; timezone: UTC; ntp_synchronized: True; servertime: 20251125T07:20:12Z
ntp_custom_servers: ['time.google.com', 'time.windows.com', 'time.apple.com']
ntp_server_status: {'216.239.35.0': 'synced', '168.61.215.74': 'uncombined', '17.253.2.35': 'uncombined'}
===set NTP mode DHCP===
ntp_mode: DHCP; timezone: UTC; ntp_synchronized: True; servertime: 20251125T07:20:19Z
ntp_custom_servers: ['time.google.com', 'time.windows.com', 'time.apple.com']
ntp_server_status: {'10.63.96.11': 'synced'}
===set NTP mode Factory===
ntp_mode: Factory; timezone: UTC; ntp_synchronized: True; servertime: 20251125T07:20:26Z
ntp_custom_servers: ['time.google.com', 'time.windows.com', 'time.apple.com']
ntp_server_status: {'134.215.155.177': 'combined', '216.229.4.69': 'synced', '69.176.84.38': 'combined', '144.34.193.110': 'combined'}
===set NTP mode Disbaled and set server time===
ntp_mode: Disabled; timezone: UTC; ntp_synchronized: False; servertime: 20251125T06:11:56Z
ntp_custom_servers: ['time.google.com', 'time.windows.com', 'time.apple.com']
ntp_server_status: {}
===set NTP mode DHCP===
ntp_mode: DHCP; timezone: UTC; ntp_synchronized: True; servertime: 20251125T07:20:35Z
ntp_custom_servers: ['time.google.com', 'time.windows.com', 'time.apple.com']
ntp_server_status: {'10.63.96.11': 'synced'}

Exceptions example:

    try:
        session.xenapi.host.set_ntp_mode(host_ref, 'Custom')
        session.xenapi.host.set_ntp_custom_servers(host_ref, [])
    except Exception as e:
        print(e)
    try:
        session.xenapi.host.set_ntp_mode(host_ref, 'DHCP')
        session.xenapi.host.set_ntp_custom_servers(host_ref, [])
        session.xenapi.host.set_ntp_mode(host_ref, 'Custom')
    except Exception as e:
        print(e)
    try:
        session.xenapi.host.set_servertime(host_ref, '20251125T14:11:55+08:00')
    except Exception as e:
        print(e)

output

['INVALID_NTP_CONFIG', "Can't set ntp_custom_servers empty when ntp_mode is Custom"]
['INVALID_NTP_CONFIG', "Can't set ntp_mode to Custom when ntp_custom_servers is empty"]
['NOT_ALLOWED_WHEN_NTP_IS_ENABLED', 'OpaqueRef:91f90f95-3a9b-d048-6f92-a4e522654540']

minglumlu · 2025-11-25T08:24:49Z

ocaml/xapi/xapi_host.ml

  if current_mode <> value then (
    let open Xapi_host_ntp in
-    let ensure_custom_servers_exist servers =
+    let ensure_servers_exist servers msg =


I think at least 3 NTP servers are required.
And it could be assert_sufficient_ntp_servers.

Ah, I find rfc8633 in chapter 3.2. Using Enough Time Sources recommends the four or more time sources. But here, I think it's just the best practice, not a hard requirement.

1 or 2 will fail definitely. This is for how NTP works.

I think "1 or 2 will fail definitely" is too strong. They are risky and uncertain but not guaranteed failure.
One server: If it goes down or drifts significantly, there’s no backup.
Two servers: If they disagree, NTP can’t determine which one is correct.

From the description of what happens with one or two servers, it looks to me NTP is unable to work reliably :)

Because we want xapi to work reliably at all times, I think it's warranted to enforce at least 3 servers.

I still insist we shouldn't strict the API settings. NTP service like chornyd will not limit the number of time sources. It's strange to encounter this error in our APIs if I am the user. If in user's internal network environment, there is only one NTP server deployed, it is hard to work.
@robhoes Will I get a vote from you on this issue.

I would prefer to not restrict this in xapi.

Then I'd prefer if the standard recommending at least 3 servers was added in the datamodel field. This is something I'll also mention to XO people to avoid issues

ocaml/xapi/xapi_host.ml

robhoes · 2025-11-27T14:44:04Z

ocaml/idl/datamodel_host.ml

            "Whether the host has booted in secure boot mode"
        ; field ~qualifier:DynamicRO ~lifecycle:[] ~ty:host_ntp_mode
-            ~default_value:(Some (VEnum "ntp_mode_dhcp")) "ntp_mode"
+            ~default_value:(Some (VEnum "DHCP")) "ntp_mode"


The default is set to DHCP here, which is relevant for the update case. This implies that before this feature, hosts relied on DHCP to set up NTP. Is that right, as I expected Factory?

It seems we have to rely on the Dbsync_slave.update_env to get the info when xapi restart for the update application.

Done. Default value of ntp_mode changes to Factory.

robhoes · 2025-11-27T14:49:17Z

ocaml/xapi/xapi_host.ml

  if current_mode <> value then (
    let open Xapi_host_ntp in
-    let ensure_custom_servers_exist servers =
+    let ensure_servers_exist servers msg =


I would prefer to not restrict this in xapi.

minglumlu · 2025-11-28T02:22:04Z

ocaml/xapi/xapi_host.ml

+          ensure_servers_exist factory_servers
+            "Can't set ntp_mode to Factory when factory ntp servers is empty" ;
+          set_servers_in_conf factory_servers
+      | `Disabled ->


I forgot one thing. Should the system clock be synced to RTC hardware clock when NTP is about to be disabled?

# Enable kernel synchronization of the real-time clock (RTC). rtcsync

In our dom0 host, chrony is configured to sync RTC after NTP synchronized. So there is no need to do it again in XAPI. I also have verified it.

Signed-off-by: Changlei Li <changlei.li@cloud.com>

Command timedatectl is used to set server time. However, if disable chronyd before set_servertime by systemctl, timedatectl may not sync the status in time, then the set-time will fail as `Failed to set time: Automatic time synchronization is enabled`. This is because systemd checks synchronization status periodically and update its own NTP flag (which is timedatectl replied on) To let timedatectl update NTP flag instantly, use timedatectl set-ntp true/false to enable/disable the NTP. Signed-off-by: Changlei Li <changlei.li@cloud.com>

The `/run/chrony-dhcp` dir can be created when chrony.sh is executable (i.e. DHCP mode) when host boot up. If host boots up with other NTP mode, the dir may not be created. Check the dir and create it if not exist. Signed-off-by: Changlei Li <changlei.li@cloud.com>

Signed-off-by: Changlei Li <changlei.li@cloud.com>

changlei-li requested review from minglumlu, psafont and robhoes November 25, 2025 07:14

minglumlu reviewed Nov 25, 2025

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minglumlu reviewed Nov 25, 2025

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minglumlu approved these changes Nov 25, 2025

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changlei-li force-pushed the private/changleli/update-ntp-mode branch 2 times, most recently from 406a201 to 4acb199 Compare November 25, 2025 10:18

robhoes reviewed Nov 27, 2025

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minglumlu reviewed Nov 28, 2025

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changlei-li added 4 commits November 28, 2025 14:40

CP-54476 Merge ntp disable/enable to ntp mode

53cbd66

Signed-off-by: Changlei Li <changlei.li@cloud.com>

Update datamodel lifecycle and bump schema

1b698f0

Signed-off-by: Changlei Li <changlei.li@cloud.com>

changlei-li force-pushed the private/changleli/update-ntp-mode branch from 4acb199 to 1b698f0 Compare November 28, 2025 06:47

robhoes approved these changes Nov 28, 2025

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changlei-li merged commit 02ee3af into xapi-project:feature/config-ntp-timezone-maxcstate Dec 1, 2025
16 checks passed

changlei-li deleted the private/changleli/update-ntp-mode branch December 1, 2025 01:11

CP-54476 Merge ntp disable/enable to ntp mode #6765

CP-54476 Merge ntp disable/enable to ntp mode #6765

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changlei-li commented Nov 25, 2025 •

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