OpenVPN client log not `logrotate`ing as expected

summary: I want to keep an OpenVPN client's main log from filling its filesystem, but I also need to keep a fairly high debug level (at least for now). My attempt to logrotate is currently not behaving as intended (though it's probably behaving as directed :-(

details:

I'm definitely underskilled as a Linux administrator, so feel free to correct any errors or misperceptions embedded below. I've got a laptop with

$ cat /etc/debian_version
jessie/sid
$ uname -rv
3.11-2-amd64 #1 SMP Debian 3.11.8-1 (2013-11-13)
$ sudo openvpn --version | head -1
OpenVPN 2.3.2 x86_64-pc-linux-gnu [SSL (OpenSSL)] [LZO] [EPOLL] [PKCS11] [eurephia] [MH] [IPv6] built on Nov 28 2013
$ sudo logrotate --version | head -1
logrotate 3.8.6

on which I'm setting up an OpenVPN client for the first time. The client is not yet working, so ISTM I need to keep my OpenVPN log @ /var/log/openvpn.log fairly informative. Unfortunately I started getting notification=Low Disk Space on "Filesystem root", since I have /var on my LVM2 root volume. After manually deleting /var/log/openvpn.log a few times, I decided, "time to learn to use logrotate". After reading a bit, I created /etc/cron.hourly/logrotate with

#!/bin/sh

test -x /usr/sbin/logrotate || exit 0
/usr/sbin/logrotate /etc/logrotate.conf

and appended the stanza for /var/log/openvpn.log below to my /etc/logrotate.conf (i.e., everything before # for OpenVPN client was in the /etc/logrotate.conf installed by debian):

# see "man logrotate" for details
# rotate log files weekly
weekly

# keep 4 weeks worth of backlogs
rotate 4

# create new (empty) log files after rotating old ones
create

# uncomment this if you want your log files compressed
#compress

# packages drop log rotation information into this directory
include /etc/logrotate.d

# no packages own wtmp, or btmp -- we'll rotate them here
/var/log/wtmp {
    missingok
    monthly
    create 0664 root utmp
    rotate 1
}

/var/log/btmp {
    missingok
    monthly
    create 0660 root utmp
    rotate 1
}

# system-specific logs may be configured here

# for OpenVPN client
/var/log/openvpn.log {
    missingok
    copytruncate
    size 100M
    rotate 5
    dateformat -%Y%m%d_%H%M
    dateext
    compress
    delaycompress
    nomail
}

I.e., my intention was that,

1. cron would run logrotate hourly.


2. Once /var/log/openvpn.log got bigger than 100 MB, logrotate would copytruncate it (to allow process=openvpn to continue to write the original logfile).


3. Each copytruncated log section would be timestamped with format=%Y%m%d_%H%M (which works at commandline with date +%Y%m%d_%H%M)


4. Each copytruncated log section would be compressed; I'm using delaycompress since it seems safer than not using it :-)


5. I would keep up to 5 log sections, and thus not more than 500 MB of OpenVPN log. (And hopefully less, since I'm compressing.)

Unfortunately, I'm still getting the root-full notifications, with situations like

$ df -h
Filesystem                   Size  Used Avail Use% Mounted on
/dev/mapper/LVM2_crypt-root   20G   20G     0 100% /
udev                          10M     0   10M   0% /dev
tmpfs                        390M  1.1M  389M   1% /run
tmpfs                        5.0M     0  5.0M   0% /run/lock
tmpfs                        1.6G  876K  1.6G   1% /run/shm
/dev/sda3                    485M   33M  423M   8% /boot
/dev/mapper/LVM2_crypt-home  322G  228G   95G  71% /home
none                         4.0K     0  4.0K   0% /sys/fs/cgroup

$ sudo rm /var/log/openvpn.log
rm: cannot remove ‘/var/log/openvpn.log’: No such file or directory

$ ls -alS /var/log/ | head
total 5521688
-rw-------  1 root root 5636743168 Mar  6 14:21 openvpn.log-20150306_%H%M
...

$ sudo rm /var/log/openvpn.log*

$ df -h
Filesystem                   Size  Used Avail Use% Mounted on
/dev/mapper/LVM2_crypt-root   20G   15G  4.3G  78% /
...

So I have 3 questions, in ascending order of importance (to me):

1. Why is logrotate timestamping incorrectly? I.e., why is it creating openvpn.log-20150306_%H%M instead of openvpn.log-20150306_1421 ?


2. Why is logrotate creating a 5-GB logfile segment, instead of rotating @ 100 MB as directed?


3. How best to fix this problem?