Add refresh-exclude-older flag to only transfer new snapshots during instance/volume refresh

[ps-gill]

This pull request resolves issue #745

[stgraber]

Looking into this one now

[stgraber]

Just did a few minor tweaks so far:

• Split the doc/rest-api.yaml changes to its own commit
• Fixed a missing API extension comment in shared/api
• Re-titled some commits

[stgraber]

There seems to be a problem with the actual logic:

root@v1:~# incus snapshot list a1
+-------+----------------------+------------+----------+
| NAME  |       TAKEN AT       | EXPIRES AT | STATEFUL |
+-------+----------------------+------------+----------+
| snap0 | 2024/11/14 07:03 UTC |            | NO       |
+-------+----------------------+------------+----------+
| snap1 | 2024/11/14 07:03 UTC |            | NO       |
+-------+----------------------+------------+----------+
| snap2 | 2024/11/14 07:04 UTC |            | NO       |
+-------+----------------------+------------+----------+
| snap3 | 2024/11/14 07:04 UTC |            | NO       |
+-------+----------------------+------------+----------+
| snap4 | 2024/11/14 07:05 UTC |            | NO       |
+-------+----------------------+------------+----------+
| snap5 | 2024/11/14 07:05 UTC |            | NO       |
+-------+----------------------+------------+----------+
| snap6 | 2024/11/14 07:05 UTC |            | NO       |
+-------+----------------------+------------+----------+
| snap7 | 2024/11/14 07:05 UTC |            | NO       |
+-------+----------------------+------------+----------+
root@v1:~# incus snapshot list v2:a1
+-------+----------------------+------------+----------+
| NAME  |       TAKEN AT       | EXPIRES AT | STATEFUL |
+-------+----------------------+------------+----------+
| snap6 | 2024/11/14 07:05 UTC |            | NO       |
+-------+----------------------+------------+----------+
| snap7 | 2024/11/14 07:05 UTC |            | NO       |
+-------+----------------------+------------+----------+
root@v1:~# incus copy a1 v2: --refresh-exclude-older --refresh
root@v1:~# incus snapshot list v2:a1
+-------+----------------------+------------+----------+
| NAME  |       TAKEN AT       | EXPIRES AT | STATEFUL |
+-------+----------------------+------------+----------+
| snap0 | 2024/11/14 07:03 UTC |            | NO       |
+-------+----------------------+------------+----------+
| snap1 | 2024/11/14 07:03 UTC |            | NO       |
+-------+----------------------+------------+----------+
| snap2 | 2024/11/14 07:04 UTC |            | NO       |
+-------+----------------------+------------+----------+
| snap3 | 2024/11/14 07:04 UTC |            | NO       |
+-------+----------------------+------------+----------+
| snap4 | 2024/11/14 07:05 UTC |            | NO       |
+-------+----------------------+------------+----------+
| snap5 | 2024/11/14 07:05 UTC |            | NO       |
+-------+----------------------+------------+----------+
| snap6 | 2024/11/14 07:05 UTC |            | NO       |
+-------+----------------------+------------+----------+
| snap7 | 2024/11/14 07:05 UTC |            | NO       |
+-------+----------------------+------------+----------+
root@v1:~# 

[stgraber]

I fixed the issue. It was the exclude flag not being passed around through migrationSinkArgs combined with then a bad check in utils.go.