Catena - Log2ram Ansible Role

Log2Ram helps not to stress a drive (like a SD Card on RaspberryPi) with continuous log writing. The script creates a /var/log mount point in RAM, so any writing to the /var/log folder will not be actually written on disk but directly on RAM. It works great in combination with Catena systemd-swap and Catena systemd-zram roles.

Role variables

log2ram

# Default
log2ram:
  # Size the log folder will reserve into the RAM
  size: 40M
  # When `true` use rsync for log syncing, when `false` use cp
  rsync: true
  # Use system mail to get notified on errors
  mail: false
  # List of folders to put in RAM
  path: ["/var/log"]
  # When `true` use zram, when `false` use tmpfs
  zram: true
  # Compression algorithm when zram is enabled
  compression: lz4

log2ram.size

Defines the size of the log folder that will be reserved into the RAM. If it's not enough, log2ram will not be able to work correctly. Please check the size of /var/log folder before making decisions. The default is 40M and it should be enough for a lot of applications. For a server with many log storage, it can be increased to 100M or more.

The available space can be increased setting the log2ram.zram variable to true and specifing a log2ram.compression algorithm to use.

log2ram.rsync

Select the log syncing method between the log directory on disk and in the RAM. When true, use rsync, instead use cp, that is also available for fallback when rsync is missing.

log2ram.mail

When true, uses the system mail binary to notify the user about errors with available RAM space. Change it to false to only use a log when there's no more place on RAM.

log2ram.path

List of folders to store in RAM. Always specify an existing folder /path/folder without using the final /.

The /path/hdd.folder will be automatically created.

Example with multiple folders:

log2ram:
  path:
    - "/var/log"
    - "/home/user/ramfolder"

log2ram.compression

It's a chose compression algorithm listed in /proc/crypto. The fastest and lightest lz4 or zstd (Zstandard) for better compression ratios, are the recommended choices.

Compressor name	Ratio	Compression	Decompress.
zstd 1.4.5 -1	2.884	500 MB/s	1660 MB/s
zlib 1.2.11 -1	2.743	90 MB/s	400 MB/s
brotli 1.0.7 -0	2.703	400 MB/s	450 MB/s
lzo1x 2.10 -1	2.106	690 MB/s	830 MB/s
lz4 1.9.2	2.101	740 MB/s	4530 MB/s
snappy 1.1.8	2.073	560 MB/s	1790 MB/s

log2ram_version

# Default
log2ram_version: "{{ log2ram.version | default('1.6.1') }}"

Version of Log2Ram to install, see GitHub releases. The version can also be set in log2ram.version but this variable has the precedence.

log2ram_journal_cleanup

# Default
log2ram_journal_cleanup: false

When is true executes the command: journalctl --vacuum-size= targeting the chosen log2ram_size - 5%. This reduces the /var/log folder size by removing the oldest systemd journals before re/start log2ram service. This should avoid most of the errors due to a too big existing folder.