Setting roll_keep to 0 does not disable it

[StroppaFR]

Issue Details

Documentation about the roll_keep log rotation option at https://caddyserver.com/docs/caddyfile/directives/log#roll_keep states the following:

roll_keep is how many log files to keep before deleting the oldest ones. Triggers when a new log file is created.
To disable roll_keep, set the value to 0.

But setting the value to 0 in Caddyfile seems to have no effect and keeps a maximum of 10 log files instead. Example Caddyfile to reproduce the issue:

mywebsite:80 {
    log {
        output file /var/log/caddy/mywebsite.log {
            roll_interval 1s
            roll_keep 0
            roll_keep_for 1d
        }
        format json
    }
    respond "OK"
}

# caddy --version
v2.11.4 h1:XKxkMTgNSizEvKG6QHue6cAsFOteU2qA61w2tKkCWi0=
# ls -la /var/log/caddy/ | grep log.gz | wc -l
10

This could be caused by this:

caddy/modules/logging/filewriter.go

Lines 258 to 260 in 4e62095

	if fw.RollKeep == 0 {
	fw.RollKeep = 10
	}

Setting the value to -1 instead removes the limit.

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No response

[steadytao]

Confirmed. I think the smallest compatible fix is to document -1 as the disabling value.

[francislavoie]

Yeah, this is a documentation problem, not an implementation problem, I think. The fix needs to happen in https://github.com/caddyserver/website (PRs welcome)