Custom NTP Configuration UI

[DigitalDJ]

Closes #516, #645, #59

Summary

• There's no web user interface for the custom NTP settings that are implemented in the back-end Go application
• This is a first-cut implementation of a "Custom" Time Synchronization option
• The options are mapped directly to the back-end configuration options
• An effort has been made to validate all fields. i.e. NTP servers must be specified when the ordering includes user-specified NTP servers

Checklist

• [ X ] Ran make test_e2e locally and passed
• [ X ] Linked to issue(s) above by issue number (e.g. Closes #<issue-number>)
• [ X ] One problem per PR (no unrelated changes)
• [ X ] Lints pass; CI green
• [ X ] Tricky parts are commented in code

[adamshiervani]

Thanks for implementing the time sync configuration and also all your other PRs!!

The functionality is solid, but I think the UI needs a remodel. The current design reflects our internal data model rather than what users actually need.

Usually there are two groups with a 95/5 ratio:

1. "Just work" - Automatic time sync, don't care how
2. "Use my servers" - Enterprise/air-gapped environments with specific NTP servers

Proposed Simplification

Two modes: Automatic | Custom

Time Synchronization
└─ [Automatic ▼]

When "Custom":

┌────────────────────────────────────────────────────────┐
│ Your NTP Servers                                       │
│ [ntp.internal.corp.com                     ] [×]       │
│ [+ Add Server]                                         │
│                                                        │
│ Your HTTP URLs (optional)                              │
│ [http://time.internal.corp.com             ] [×]       │
│ [+ Add URL]                                            │
│                                                        │
│ ☑ Fall back to built-in servers if yours fail         │
│ ☐ Also try NTP servers from DHCP (for isolated networks)│
└────────────────────────────────────────────────────────┘

Backend Mapping

UI State	Backend Values
Automatic	time_sync_mode: "ntp_and_http", default ordering
Custom + fallback	mode: "custom", ordering: [user_ntp, user_http, ntp, http], disable_fallback: false
Custom + fallback + DHCP	Same but ordering includes ntp_dhcp after user sources
Custom, no fallback	ordering: [user_ntp, user_http], disable_fallback: true

[DigitalDJ]

Hi there! I agree with your comments, and that's what I thought of doing. I implemented this as a first-pass.... just to basically understand what the model was behind the scenes. At least this gives power-users access to the advanced features.

From here, yeah, I agree. Things like "Disable Fallback" shouldn't be possible with no specified NTP/HTTP URLs.... A lot of the things should be "automatic" unless specified. Then even the "specified" things should only be the servers / URLs. As long as things behind the scenes only hit the servers specified, I think offline users / air-gaped users would be satisfied.

I might get around to simplifying this over the next couple of weeks....but not being a React / TS dev...this makes it a bit of a struggle :P

[IDisposable]

Custom + fallback + DHCP Same but ordering includes ntp_dhcp after user sources

As a network engineer, I would expect DHCP to be honored first

[Torstein-Eide]

As a network engineer, I would expect DHCP to be honored first

I disagree, and it depends on wording, for the SNTP client. (I don't think this i a full stack NTP client, since it doesn't need it.)
Similar to how systemd-timesyncd.service, handles it.

NTP=

A space-separated list of NTP server host names or IP addresses. During runtime this list is combined with any per-interface NTP servers acquired from systemd-networkd.service(8). systemd-timesyncd will contact all configured system or per-interface servers in turn, until one responds. When the empty string is assigned, the list of NTP servers is reset, and all prior assignments will have no effect. This setting defaults to an empty list.

FallbackNTP=

A space-separated list of NTP server host names or IP addresses to be used as the fallback NTP servers. Any per-interface NTP servers obtained from systemd-networkd.service(8) take precedence over this setting, as do any servers set via NTP= above. This setting is hence only relevant if no other NTP server information is known. When the empty string is assigned, the list of NTP servers is reset, and all prior assignments will have no effect. If this option is not given, a compiled-in list of NTP servers is used.

Ref: timesyncd.conf(5)