There recently was talks on Meta about the support period of LTS and non-LTS releases on this site. In addition, I saw the mention of Ubuntu Core in a comment, and this got me wondering what the support period for Ubuntu Core actually is, and if it follows the support period for Ubuntu LTS.

Canonical states this on the Ubuntu Core page:

Ubuntu Core gets 10 years of Canonical maintenance. Your smallest devices are now as secure as your servers. No other embedded Linux comes close.

Also, as far as I understand, Ubuntu Core 16 is still the default "core" release for snaps. This is supported by the fact that Core 16 (just named "core" in snap) has update cycle and versioning that exactly follows the snapd version.

Output of snap info snapd:

<...>

type:         snapd

snap-id:      PMrrV4ml8uWuEUDBT8dSGnKUYbevVhc4

tracking:     latest/stable

refresh-date: 9 days ago, at 23:27 CEST

channels:

  latest/stable:    2.51.4                  2021-08-25 (12883) 33MB -

  latest/candidate: 2.51.7                  2021-08-31 (13170) 33MB -

  latest/beta:      2.51.7                  2021-08-27 (13170) 33MB -

  latest/edge:      2.51.7+git1522.gc980bde 2021-08-31 (13216) 42MB -

installed:          2.51.4                             (12883) 33MB snapd

Output of snap info core:

<...>

type:         core

snap-id:      99T7MUlRhtI3U0QFgl5mXXESAiSwt776

tracking:     latest/stable

refresh-date: 9 days ago, at 23:27 CEST

channels:

  latest/stable:    16-2.51.4                  2021-08-25 (11606) 104MB -

  latest/candidate: 16-2.51.7                  2021-08-31 (11743) 104MB -

  latest/beta:      16-2.51.7                  2021-08-27 (11743) 104MB -

  latest/edge:      16-2.51.7+git3168.3a0f4248 2021-09-01 (11771) 112MB -

installed:          16-2.51.4                             (11606) 104MB core

Another element in the mix is that Ubuntu Core isn't released completely in parallel with the LTS releases. For instance, Ubuntu Core 20 was released in January 2021, i.e. 9 months after the first release of Ubuntu 20.04.

So do Ubuntu Core releases follow the same 5-year support period as LTS releases, or is it indeed 10 years, per the Canonical security maintainance period?

This also ties into the recent topic of How long do we support Ubuntu flavors?, as well as my suggestion to rephrase the Help Center explanation.

For an answer to be considered satisfactory, the following elements should be addressed:

• The relation between Ubuntu LTS and Core releases, including the difference in release times


• The "special" status of Ubuntu Core 16 (named core in snap) as the base that follows snapd versioning


• Reflections on how this should affect support time on Ask Ubuntu


• Reference to official sources and/or Ubuntu team members (as opposed to speculation)