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Backups live 1 day longer than value in AUTO_BACKUP_DAYS_TO_LIVE #289

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ikaruswill opened this issue Mar 16, 2021 · 5 comments · Fixed by #290
Closed

Backups live 1 day longer than value in AUTO_BACKUP_DAYS_TO_LIVE #289

ikaruswill opened this issue Mar 16, 2021 · 5 comments · Fixed by #290

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@ikaruswill
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ikaruswill commented Mar 16, 2021 •
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Background

There's an issue with the backups living exactly 1 day longer than they should, as demonstrated in my configuration and the current state of the backups directory below.

This is a big deal for people like myself who run Valheim servers on limited storage capacity, therefore timely pruning of backups is crucial.

Expected behaviour

  • Current time is:
root@valheim-59978997b9-5kv96:/home/steam/backups# date
Tue Mar 16 17:16:19 +08 2021
  • With a TTL of 1 day, I envisioned backups to live for exactly 24 hours, and therefore, the earliest backup that I should see is: Tue Mar 15 17:15:00 +08 2021

Current behaviour

I'm still seeing backups up till Tue Mar 15 00:00:00 +08 2021 which are nearly 2 days old

Problem

I've dug and found that the error lies in invalid use of the -mtime +${AUTO_BACKUP_DAYS_TO_LIVE:-5} parameter in find in the auto backup script.

The POSIX specification for find states:

-mtime n
The primary shall evaluate as true if the file modification time subtracted from the initialization time, divided by 86400 (with any remainder discarded), is n.

  • In my specific example, taking the earliest backup archive on Mar 15 00:00 +08, the linux epoch timestamp is:
    Mar 15 00:00 +08 2021 => 1615737600

  • Current time:

root@valheim-59978997b9-5kv96:/home/steam/backups# date +%s
1615886883
  • Performing the calculations:
1615886883 - 1615737600 = 149283
149283 / 86400 = 1.7278125

It makes sense here that any files more than 1 day old should be caught by the find command

Cause

However, when using -mtime +${AUTO_BACKUP_DAYS_TO_LIVE:-5}, which means to discard any backups with mtime <-> current time difference > AUTO_BACKUP_DAYS_TO_LIVE, digging further into the POSIX spec for find:

In the descriptions, wherever n is used as a primary argument, it shall be interpreted as a decimal integer optionally preceded by a ( '+' ) or ( '-' ), as follows:
+n More than n.
n Exactly n.
-n Less than n.

Note that the n here is being interpreted as a decimal integer means that mtime difference value is interpreted as an integer.

  • So the missing step in the above calculation is:
n = int(1.7278125) = 1

Using mtime +n means that it will only find files with int(n) > 1, where the value 1.7 will not make the cut until it reaches 2.0, which by then means it is already 2 days old (48h)

Suggested fix

  • Remove the +, demonstrated in the Proof of concept section below
  • Will file the PR shortly.

Supporting information

Environment variables:

root@valheim-59978997b9-5kv96:/home/steam/backups# env | grep AUTO
AUTO_BACKUP_REMOVE_OLD=1
AUTO_UPDATE=1
AUTO_BACKUP_ON_SHUTDOWN=0
AUTO_BACKUP=1
AUTO_BACKUP_ON_UPDATE=0
AUTO_BACKUP_DAYS_TO_LIVE=1
AUTO_UPDATE_SCHEDULE=5 8 * * *
AUTO_BACKUP_SCHEDULE=*/15 * * * *

Backups directory:

root@valheim-59978997b9-5kv96:/home/steam/backups# ls -la
total 5709372
drwxr-xr-x 2 steam steam    28672 Mar 16 17:15 .
drwxr-xr-x 1 steam steam     4096 Mar 16 02:35 ..
-rw-r--r-- 1 steam steam 38013742 Mar 15 00:00 20210315-000001-backup.tar.gz
-rw-r--r-- 1 steam steam 38013742 Mar 15 00:15 20210315-001501-backup.tar.gz
-rw-r--r-- 1 steam steam 38042424 Mar 15 00:30 20210315-003001-backup.tar.gz
-rw-r--r-- 1 steam steam 38060625 Mar 15 00:45 20210315-004501-backup.tar.gz
-rw-r--r-- 1 steam steam 38060631 Mar 15 01:00 20210315-010001-backup.tar.gz
-rw-r--r-- 1 steam steam 38060631 Mar 15 01:15 20210315-011502-backup.tar.gz
-rw-r--r-- 1 steam steam 38060629 Mar 15 01:30 20210315-013001-backup.tar.gz
-rw-r--r-- 1 steam steam 38060626 Mar 15 01:45 20210315-014502-backup.tar.gz
-rw-r--r-- 1 steam steam 38060625 Mar 15 02:00 20210315-020001-backup.tar.gz
-rw-r--r-- 1 steam steam 38060625 Mar 15 02:15 20210315-021501-backup.tar.gz
-rw-r--r-- 1 steam steam 38060626 Mar 15 02:30 20210315-023001-backup.tar.gz
-rw-r--r-- 1 steam steam 38060626 Mar 15 02:45 20210315-024501-backup.tar.gz
-rw-r--r-- 1 steam steam 38060624 Mar 15 03:00 20210315-030001-backup.tar.gz
-rw-r--r-- 1 steam steam 38060624 Mar 15 03:15 20210315-031501-backup.tar.gz
-rw-r--r-- 1 steam steam 38060625 Mar 15 03:30 20210315-033001-backup.tar.gz
-rw-r--r-- 1 steam steam 38060628 Mar 15 03:45 20210315-034501-backup.tar.gz
-rw-r--r-- 1 steam steam 38060628 Mar 15 04:00 20210315-040001-backup.tar.gz
-rw-r--r-- 1 steam steam 38060628 Mar 15 04:15 20210315-041501-backup.tar.gz
-rw-r--r-- 1 steam steam 38060628 Mar 15 04:30 20210315-043001-backup.tar.gz
-rw-r--r-- 1 steam steam 38060630 Mar 15 04:45 20210315-044501-backup.tar.gz
-rw-r--r-- 1 steam steam 38060626 Mar 15 05:00 20210315-050001-backup.tar.gz
-rw-r--r-- 1 steam steam 38060626 Mar 15 05:15 20210315-051501-backup.tar.gz
-rw-r--r-- 1 steam steam 38060624 Mar 15 05:30 20210315-053001-backup.tar.gz
-rw-r--r-- 1 steam steam 38060630 Mar 15 05:45 20210315-054502-backup.tar.gz
-rw-r--r-- 1 steam steam 38060630 Mar 15 06:00 20210315-060001-backup.tar.gz
-rw-r--r-- 1 steam steam 38060625 Mar 15 06:15 20210315-061501-backup.tar.gz
-rw-r--r-- 1 steam steam 38060626 Mar 15 06:30 20210315-063001-backup.tar.gz
-rw-r--r-- 1 steam steam 38060626 Mar 15 06:45 20210315-064502-backup.tar.gz
-rw-r--r-- 1 steam steam 38060626 Mar 15 07:00 20210315-070001-backup.tar.gz
-rw-r--r-- 1 steam steam 38060625 Mar 15 07:15 20210315-071501-backup.tar.gz
-rw-r--r-- 1 steam steam 38060623 Mar 15 07:30 20210315-073001-backup.tar.gz
-rw-r--r-- 1 steam steam 38060621 Mar 15 07:45 20210315-074501-backup.tar.gz
-rw-r--r-- 1 steam steam 38060621 Mar 15 08:00 20210315-080001-backup.tar.gz
-rw-r--r-- 1 steam steam 38060625 Mar 15 08:15 20210315-081501-backup.tar.gz
-rw-r--r-- 1 steam steam 38060623 Mar 15 08:30 20210315-083001-backup.tar.gz
-rw-r--r-- 1 steam steam 38060620 Mar 15 08:45 20210315-084501-backup.tar.gz
-rw-r--r-- 1 steam steam 38060620 Mar 15 09:00 20210315-090001-backup.tar.gz
-rw-r--r-- 1 steam steam 38060622 Mar 15 09:15 20210315-091501-backup.tar.gz
-rw-r--r-- 1 steam steam 38060629 Mar 15 09:30 20210315-093001-backup.tar.gz
-rw-r--r-- 1 steam steam 38060630 Mar 15 09:45 20210315-094501-backup.tar.gz
-rw-r--r-- 1 steam steam 38060630 Mar 15 10:00 20210315-100001-backup.tar.gz
-rw-r--r-- 1 steam steam 38060625 Mar 15 10:15 20210315-101501-backup.tar.gz
-rw-r--r-- 1 steam steam 38060626 Mar 15 10:30 20210315-103001-backup.tar.gz
-rw-r--r-- 1 steam steam 38060632 Mar 15 10:45 20210315-104501-backup.tar.gz
-rw-r--r-- 1 steam steam 38060632 Mar 15 11:00 20210315-110002-backup.tar.gz
-rw-r--r-- 1 steam steam 38060626 Mar 15 11:15 20210315-111501-backup.tar.gz
-rw-r--r-- 1 steam steam 38060628 Mar 15 11:30 20210315-113001-backup.tar.gz
-rw-r--r-- 1 steam steam 38060629 Mar 15 11:45 20210315-114501-backup.tar.gz
-rw-r--r-- 1 steam steam 38060629 Mar 15 12:00 20210315-120001-backup.tar.gz
-rw-r--r-- 1 steam steam 38060626 Mar 15 12:15 20210315-121501-backup.tar.gz
-rw-r--r-- 1 steam steam 38060626 Mar 15 12:30 20210315-123001-backup.tar.gz
-rw-r--r-- 1 steam steam 38060626 Mar 15 12:45 20210315-124501-backup.tar.gz
-rw-r--r-- 1 steam steam 38060626 Mar 15 13:00 20210315-130001-backup.tar.gz
-rw-r--r-- 1 steam steam 38060629 Mar 15 13:15 20210315-131501-backup.tar.gz
-rw-r--r-- 1 steam steam 38060632 Mar 15 13:30 20210315-133001-backup.tar.gz
-rw-r--r-- 1 steam steam 38060629 Mar 15 13:45 20210315-134501-backup.tar.gz
-rw-r--r-- 1 steam steam 38060629 Mar 15 14:00 20210315-140001-backup.tar.gz
-rw-r--r-- 1 steam steam 38060626 Mar 15 14:15 20210315-141501-backup.tar.gz
-rw-r--r-- 1 steam steam 38060629 Mar 15 14:30 20210315-143001-backup.tar.gz
-rw-r--r-- 1 steam steam 38060623 Mar 15 14:45 20210315-144501-backup.tar.gz
-rw-r--r-- 1 steam steam 38060623 Mar 15 15:00 20210315-150001-backup.tar.gz
-rw-r--r-- 1 steam steam 38060627 Mar 15 15:15 20210315-151501-backup.tar.gz
-rw-r--r-- 1 steam steam 38060627 Mar 15 15:30 20210315-153001-backup.tar.gz
-rw-r--r-- 1 steam steam 38060622 Mar 15 15:45 20210315-154501-backup.tar.gz
-rw-r--r-- 1 steam steam 38060622 Mar 15 16:00 20210315-160001-backup.tar.gz
-rw-r--r-- 1 steam steam 38060625 Mar 15 16:15 20210315-161501-backup.tar.gz
-rw-r--r-- 1 steam steam 38060622 Mar 15 16:30 20210315-163001-backup.tar.gz
-rw-r--r-- 1 steam steam 38060623 Mar 15 16:45 20210315-164502-backup.tar.gz
-rw-r--r-- 1 steam steam 38060623 Mar 15 17:00 20210315-170001-backup.tar.gz
-rw-r--r-- 1 steam steam 38060622 Mar 15 17:15 20210315-171501-backup.tar.gz
-rw-r--r-- 1 steam steam 38060627 Mar 15 17:30 20210315-173001-backup.tar.gz
-rw-r--r-- 1 steam steam 38060628 Mar 15 17:45 20210315-174501-backup.tar.gz
-rw-r--r-- 1 steam steam 38060628 Mar 15 18:00 20210315-180001-backup.tar.gz
-rw-r--r-- 1 steam steam 38060629 Mar 15 18:15 20210315-181501-backup.tar.gz
-rw-r--r-- 1 steam steam 38060627 Mar 15 18:30 20210315-183001-backup.tar.gz
-rw-r--r-- 1 steam steam 38060631 Mar 15 18:45 20210315-184501-backup.tar.gz
-rw-r--r-- 1 steam steam 38060631 Mar 15 19:00 20210315-190001-backup.tar.gz
-rw-r--r-- 1 steam steam 38060626 Mar 15 19:15 20210315-191501-backup.tar.gz
-rw-r--r-- 1 steam steam 38060624 Mar 15 19:30 20210315-193001-backup.tar.gz
-rw-r--r-- 1 steam steam 38060632 Mar 15 19:45 20210315-194501-backup.tar.gz
-rw-r--r-- 1 steam steam 38060632 Mar 15 20:00 20210315-200001-backup.tar.gz
-rw-r--r-- 1 steam steam 38060626 Mar 15 20:15 20210315-201501-backup.tar.gz
-rw-r--r-- 1 steam steam 38060630 Mar 15 20:30 20210315-203001-backup.tar.gz
-rw-r--r-- 1 steam steam 38060630 Mar 15 20:45 20210315-204501-backup.tar.gz
-rw-r--r-- 1 steam steam 38060629 Mar 15 21:00 20210315-210001-backup.tar.gz
-rw-r--r-- 1 steam steam 38060625 Mar 15 21:15 20210315-211501-backup.tar.gz
-rw-r--r-- 1 steam steam 38060621 Mar 15 21:30 20210315-213002-backup.tar.gz
-rw-r--r-- 1 steam steam 38060621 Mar 15 21:45 20210315-214501-backup.tar.gz
-rw-r--r-- 1 steam steam 38060625 Mar 15 22:00 20210315-220001-backup.tar.gz
-rw-r--r-- 1 steam steam 38060626 Mar 15 22:15 20210315-221501-backup.tar.gz
-rw-r--r-- 1 steam steam 38060622 Mar 15 22:30 20210315-223001-backup.tar.gz
-rw-r--r-- 1 steam steam 38060622 Mar 15 22:45 20210315-224501-backup.tar.gz
-rw-r--r-- 1 steam steam 38066919 Mar 15 23:00 20210315-230001-backup.tar.gz
-rw-r--r-- 1 steam steam 38096039 Mar 15 23:15 20210315-231501-backup.tar.gz
-rw-r--r-- 1 steam steam 38190010 Mar 15 23:30 20210315-233001-backup.tar.gz
-rw-r--r-- 1 steam steam 38190010 Mar 15 23:45 20210315-234501-backup.tar.gz
-rw-r--r-- 1 steam steam 38304878 Mar 16 00:00 20210316-000001-backup.tar.gz
-rw-r--r-- 1 steam steam 38413606 Mar 16 00:15 20210316-001502-backup.tar.gz
-rw-r--r-- 1 steam steam 38535624 Mar 16 00:30 20210316-003001-backup.tar.gz
-rw-r--r-- 1 steam steam 38535624 Mar 16 00:45 20210316-004501-backup.tar.gz
-rw-r--r-- 1 steam steam 38661742 Mar 16 01:00 20210316-010002-backup.tar.gz
-rw-r--r-- 1 steam steam 38796817 Mar 16 01:15 20210316-011501-backup.tar.gz
-rw-r--r-- 1 steam steam 38916870 Mar 16 01:30 20210316-013001-backup.tar.gz
-rw-r--r-- 1 steam steam 38916870 Mar 16 01:45 20210316-014501-backup.tar.gz
-rw-r--r-- 1 steam steam 39054157 Mar 16 02:00 20210316-020001-backup.tar.gz
-rw-r--r-- 1 steam steam 39208318 Mar 16 02:15 20210316-021501-backup.tar.gz
-rw-r--r-- 1 steam steam 39278367 Mar 16 02:30 20210316-023001-backup.tar.gz
-rw-r--r-- 1 steam steam 39278366 Mar 16 02:45 20210316-024501-backup.tar.gz
-rw-r--r-- 1 steam steam 34436290 Mar 16 03:00 20210316-030001-backup.tar.gz
-rw-r--r-- 1 steam steam 34436290 Mar 16 03:15 20210316-031501-backup.tar.gz
-rw-r--r-- 1 steam steam 29591240 Mar 16 03:30 20210316-033001-backup.tar.gz
-rw-r--r-- 1 steam steam 29591240 Mar 16 03:45 20210316-034501-backup.tar.gz
-rw-r--r-- 1 steam steam 29591240 Mar 16 04:00 20210316-040001-backup.tar.gz
-rw-r--r-- 1 steam steam 29591240 Mar 16 04:15 20210316-041501-backup.tar.gz
-rw-r--r-- 1 steam steam 29591237 Mar 16 04:30 20210316-043001-backup.tar.gz
-rw-r--r-- 1 steam steam 29591236 Mar 16 04:45 20210316-044501-backup.tar.gz
-rw-r--r-- 1 steam steam 29591239 Mar 16 05:00 20210316-050001-backup.tar.gz
-rw-r--r-- 1 steam steam 29591239 Mar 16 05:15 20210316-051501-backup.tar.gz
-rw-r--r-- 1 steam steam 29591237 Mar 16 05:30 20210316-053001-backup.tar.gz
-rw-r--r-- 1 steam steam 29591239 Mar 16 05:45 20210316-054501-backup.tar.gz
-rw-r--r-- 1 steam steam 29591241 Mar 16 06:00 20210316-060001-backup.tar.gz
-rw-r--r-- 1 steam steam 29591241 Mar 16 06:15 20210316-061501-backup.tar.gz
-rw-r--r-- 1 steam steam 29591234 Mar 16 06:30 20210316-063001-backup.tar.gz
-rw-r--r-- 1 steam steam 29591239 Mar 16 06:45 20210316-064501-backup.tar.gz
-rw-r--r-- 1 steam steam 29591237 Mar 16 07:00 20210316-070001-backup.tar.gz
-rw-r--r-- 1 steam steam 29591237 Mar 16 07:15 20210316-071501-backup.tar.gz
-rw-r--r-- 1 steam steam 29591236 Mar 16 07:30 20210316-073001-backup.tar.gz
-rw-r--r-- 1 steam steam 29591236 Mar 16 07:45 20210316-074501-backup.tar.gz
-rw-r--r-- 1 steam steam 29591232 Mar 16 08:00 20210316-080001-backup.tar.gz
-rw-r--r-- 1 steam steam 29591232 Mar 16 08:15 20210316-081501-backup.tar.gz
-rw-r--r-- 1 steam steam 29591237 Mar 16 08:30 20210316-083001-backup.tar.gz
-rw-r--r-- 1 steam steam 29591236 Mar 16 08:45 20210316-084501-backup.tar.gz
-rw-r--r-- 1 steam steam 29591235 Mar 16 09:00 20210316-090001-backup.tar.gz
-rw-r--r-- 1 steam steam 29591235 Mar 16 09:15 20210316-091501-backup.tar.gz
-rw-r--r-- 1 steam steam 29591235 Mar 16 09:30 20210316-093001-backup.tar.gz
-rw-r--r-- 1 steam steam 29591237 Mar 16 09:45 20210316-094501-backup.tar.gz
-rw-r--r-- 1 steam steam 29591239 Mar 16 10:00 20210316-100001-backup.tar.gz
-rw-r--r-- 1 steam steam 29591239 Mar 16 10:15 20210316-101501-backup.tar.gz
-rw-r--r-- 1 steam steam 29591245 Mar 16 10:30 20210316-103001-backup.tar.gz
-rw-r--r-- 1 steam steam 29591233 Mar 16 10:45 20210316-104502-backup.tar.gz
-rw-r--r-- 1 steam steam 29591231 Mar 16 11:00 20210316-110001-backup.tar.gz
-rw-r--r-- 1 steam steam 29591231 Mar 16 11:15 20210316-111501-backup.tar.gz
-rw-r--r-- 1 steam steam 29591235 Mar 16 11:30 20210316-113001-backup.tar.gz
-rw-r--r-- 1 steam steam 29591234 Mar 16 11:45 20210316-114502-backup.tar.gz
-rw-r--r-- 1 steam steam 29570149 Mar 16 12:00 20210316-120001-backup.tar.gz
-rw-r--r-- 1 steam steam 29591227 Mar 16 12:15 20210316-121501-backup.tar.gz
-rw-r--r-- 1 steam steam 29591235 Mar 16 12:30 20210316-123001-backup.tar.gz
-rw-r--r-- 1 steam steam 29591238 Mar 16 12:45 20210316-124501-backup.tar.gz
-rw-r--r-- 1 steam steam 29591238 Mar 16 13:00 20210316-130002-backup.tar.gz
-rw-r--r-- 1 steam steam 29591235 Mar 16 13:15 20210316-131501-backup.tar.gz
-rw-r--r-- 1 steam steam 29591237 Mar 16 13:30 20210316-133001-backup.tar.gz
-rw-r--r-- 1 steam steam 29591237 Mar 16 13:45 20210316-134502-backup.tar.gz
-rw-r--r-- 1 steam steam 29591237 Mar 16 14:00 20210316-140001-backup.tar.gz
-rw-r--r-- 1 steam steam 29591237 Mar 16 14:15 20210316-141501-backup.tar.gz
-rw-r--r-- 1 steam steam 29591237 Mar 16 14:30 20210316-143001-backup.tar.gz
-rw-r--r-- 1 steam steam 29591240 Mar 16 14:45 20210316-144501-backup.tar.gz
-rw-r--r-- 1 steam steam 29591240 Mar 16 15:00 20210316-150001-backup.tar.gz
-rw-r--r-- 1 steam steam 29591231 Mar 16 15:15 20210316-151501-backup.tar.gz
-rw-r--r-- 1 steam steam 29591239 Mar 16 15:30 20210316-153001-backup.tar.gz
-rw-r--r-- 1 steam steam 29591243 Mar 16 15:45 20210316-154501-backup.tar.gz
-rw-r--r-- 1 steam steam 29591243 Mar 16 16:00 20210316-160001-backup.tar.gz
-rw-r--r-- 1 steam steam 29591237 Mar 16 16:15 20210316-161501-backup.tar.gz
-rw-r--r-- 1 steam steam 29591237 Mar 16 16:30 20210316-163001-backup.tar.gz
-rw-r--r-- 1 steam steam 29591239 Mar 16 16:45 20210316-164501-backup.tar.gz
-rw-r--r-- 1 steam steam 29591239 Mar 16 17:00 20210316-170001-backup.tar.gz
-rw-r--r-- 1 steam steam 29591235 Mar 16 17:15 20210316-171501-backup.tar.gz

Proof of Concept

root@valheim-59978997b9-5kv96:/home/steam/backups# find /home/steam/backups -mtime 1 -exec echo {} \;
/home/steam/backups/20210315-124501-backup.tar.gz
/home/steam/backups/20210315-133001-backup.tar.gz
/home/steam/backups/20210315-074501-backup.tar.gz
/home/steam/backups/20210315-171501-backup.tar.gz
/home/steam/backups/20210315-123001-backup.tar.gz
/home/steam/backups/20210315-134501-backup.tar.gz
/home/steam/backups/20210315-130001-backup.tar.gz
/home/steam/backups/20210315-011502-backup.tar.gz
/home/steam/backups/20210315-073001-backup.tar.gz
/home/steam/backups/20210315-010001-backup.tar.gz
/home/steam/backups/20210315-080001-backup.tar.gz
/home/steam/backups/20210315-071501-backup.tar.gz
/home/steam/backups/20210315-103001-backup.tar.gz
/home/steam/backups/20210315-121501-backup.tar.gz
/home/steam/backups/20210315-050001-backup.tar.gz
/home/steam/backups/20210315-120001-backup.tar.gz
/home/steam/backups/20210315-070001-backup.tar.gz
/home/steam/backups/20210315-081501-backup.tar.gz
/home/steam/backups/20210315-150001-backup.tar.gz
/home/steam/backups/20210315-110002-backup.tar.gz
/home/steam/backups/20210315-004501-backup.tar.gz
/home/steam/backups/20210315-030001-backup.tar.gz
/home/steam/backups/20210315-114501-backup.tar.gz
/home/steam/backups/20210315-111501-backup.tar.gz
/home/steam/backups/20210315-094501-backup.tar.gz
/home/steam/backups/20210315-160001-backup.tar.gz
/home/steam/backups/20210315-063001-backup.tar.gz
/home/steam/backups/20210315-061501-backup.tar.gz
/home/steam/backups/20210315-064502-backup.tar.gz
/home/steam/backups/20210315-003001-backup.tar.gz
/home/steam/backups/20210315-104501-backup.tar.gz
/home/steam/backups/20210315-040001-backup.tar.gz
/home/steam/backups/20210315-144501-backup.tar.gz
/home/steam/backups/20210315-164502-backup.tar.gz
/home/steam/backups/20210315-021501-backup.tar.gz
/home/steam/backups/20210315-001501-backup.tar.gz
/home/steam/backups/20210315-161501-backup.tar.gz
/home/steam/backups/20210315-101501-backup.tar.gz
/home/steam/backups/20210315-020001-backup.tar.gz
/home/steam/backups/20210315-174501-backup.tar.gz
/home/steam/backups/20210315-143001-backup.tar.gz
/home/steam/backups/20210315-024501-backup.tar.gz
/home/steam/backups/20210315-090001-backup.tar.gz
/home/steam/backups/20210315-031501-backup.tar.gz
/home/steam/backups/20210315-013001-backup.tar.gz
/home/steam/backups/20210315-000001-backup.tar.gz
/home/steam/backups/20210315-051501-backup.tar.gz
/home/steam/backups/20210315-163001-backup.tar.gz
/home/steam/backups/20210315-173001-backup.tar.gz
/home/steam/backups/20210315-141501-backup.tar.gz
/home/steam/backups/20210315-091501-backup.tar.gz
/home/steam/backups/20210315-100001-backup.tar.gz
/home/steam/backups/20210315-023001-backup.tar.gz
/home/steam/backups/20210315-041501-backup.tar.gz
/home/steam/backups/20210315-113001-backup.tar.gz
/home/steam/backups/20210315-140001-backup.tar.gz
/home/steam/backups/20210315-153001-backup.tar.gz
/home/steam/backups/20210315-093001-backup.tar.gz
/home/steam/backups/20210315-083001-backup.tar.gz
/home/steam/backups/20210315-060001-backup.tar.gz
/home/steam/backups/20210315-131501-backup.tar.gz
/home/steam/backups/20210315-034501-backup.tar.gz
/home/steam/backups/20210315-053001-backup.tar.gz
/home/steam/backups/20210315-170001-backup.tar.gz
/home/steam/backups/20210315-054502-backup.tar.gz
/home/steam/backups/20210315-084501-backup.tar.gz
/home/steam/backups/20210315-014502-backup.tar.gz
/home/steam/backups/20210315-151501-backup.tar.gz
/home/steam/backups/20210315-033001-backup.tar.gz
/home/steam/backups/20210315-043001-backup.tar.gz
/home/steam/backups/20210315-044501-backup.tar.gz
/home/steam/backups/20210315-154501-backup.tar.gz
ikaruswill pushed a commit to ikaruswill/valheim-docker that referenced this issue Mar 16, 2021
Remove + from find -mtime
48dfcf1 
Fixes mbround18#289
@ikaruswill ikaruswill mentioned this issue Mar 16, 2021
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ikaruswill pushed a commit to ikaruswill/valheim-docker that referenced this issue Mar 16, 2021
@ikaruswill
Remove + from find -mtime
2e918e1 
Fixes mbround18#289
ikaruswill added a commit to ikaruswill/valheim-docker that referenced this issue Mar 16, 2021
@ikaruswill
Remove + from find -mtime
08af441 
Fixes mbround18#289
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CosmicHorrorDev commented Mar 16, 2021 •
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This is a common point of confusion for a lot of people so it may be good to have DAYS_TO_LIVE match it's name more like the linked PR attempts to do.

The problem with just removing the + is that it means that it will no longer match on backups that are older than the specified time (say the container is shutdown for a full day, you now would have backups that never get removed). You could of course duplicate the find where one uses + and another doesn't to get >=, but at that point just subtracting one from DAYS_TO_LIVE is basically equivalent (insignificant time difference).

Thinking on it more, we would probably want to handle DAYS_TO_LIVE being 0 specifically for the above since it would become -1 which would mean less than 1 day. Maybe going for >= would actually be simpler here?

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ikaruswill commented Mar 17, 2021 •
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Good catch @LovecraftianHorror

Thinking about it, I'm actually more for using AUTO_BACKUP_DAYS_TO_LIVE - 1 as the find argument and specifically handle the 0 and negative cases which we seemed to not handle, by forcing them to 1 which is the smallest possible value.

Having a 0 value on the mtime may have undefined behaviour, or result in unnecessary disk writes with the backups being deleted right after they are created.

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Sounds good to me. I think having days to live being 0 and subtracting 1 is still well defined. find /path -mtime +-1 will match on all files which sounds right for wanting 0 days to live. Because of the ordering too having 0 days to live would keep only the most recently created backup (since backups are pruned before being created).

I think that covers any other negative values too, even though at that point the user's configuration would already be quite odd, so honestly I think just subtracting one would work fine, unless people have any other notable points they want covered.

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ikaruswill commented Mar 17, 2021 •
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In the script's case backups are pruned after new backups are created, so 0 days to live will simply delete all backups. I'll shift the backup pruning step before the creation of new backups so 0 days to live works.

You have a point on how +-1 handles all the other cases since it selects all files essentially. I have not personally tried that until now. Interesting.

Edit: Updated PR

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Oh woops, misremembered 😅

Thanks for catching that

mbround18 pushed a commit that referenced this issue Mar 20, 2021
@ikaruswill
Subtract 1 from AUTO_BACKUP_DAYS_TO_LIVE and prune before creating ba…
7a46d27 
…ckup (#290)

* Remove + from find -mtime

Fixes #289

* Revert "Remove + from find -mtime"

This reverts commit 08af441.

* Subtract 1 from AUTO_BACKUP_DAYS_TO_LIVE

Before passing to find mtime argument as +${AUTO_BACKUP_DAYS_TO_LIVE}
Also add log message to indicate old backup removal

* Move backup creation step to after backups are pruned

To handle case where AUTO_BACKUP_DAYS_TO_LIVE == 0 deletes all backups including latest.
New behaviour would be to only retain latest backup and delete all others.

* Fix typo from testing

Also remove duplicated log message
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Subtract 1 from AUTO_BACKUP_DAYS_TO_LIVE and prune before creating backup ikaruswill/valheim-docker
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