This document describes how to safely reduce the size of an LXC container before migrating it to Incus or copying it to a remote server. It provides commands to identify large directories, remove unnecessary data, and clean up legacy components.

1. Identify Large Directories

Run these commands inside the container:

du -xhd1 /
du -xhd1 /var
du -xhd1 /var/lib
du -xhd1 /usr

Use ncdu for an interactive view:

apt install ncdu
ncdu /

2. Clean System Logs

Check journal usage

journalctl --disk-usage

Reduce journal to 200M

journalctl --vacuum-size=200M

Re-check:

journalctl --disk-usage
du -sh /var/log/journal

3. Clean APT Cache

apt clean
rm -rf /var/cache/apt/archives/partial/*
du -sh /var/cache/apt

Optional autoremove:

apt autoremove --purge

4. Remove Unused MySQL Databases

List databases

mysql -e "SHOW DATABASES;"

Drop legacy databases

Example:

mysql -e "DROP DATABASE kafrep;"
mysql -e "DROP DATABASE 3dcp;"
mysql -e "DROP DATABASE b3dcp;"

Optional: purge old binary logs

mysql -e "PURGE BINARY LOGS BEFORE NOW() - INTERVAL 7 DAY;"

Check size again:

du -sh /var/lib/mysql

5. Remove Legacy MySQL Backups

Show matching backups

find /var/backups/automysqlbackup -type f \( \
    -name 'kafrep*' -o \
    -name '3dcp*' -o \
    -name 'b3dcp*' \
\) -print

Delete matching backups

find /var/backups/automysqlbackup -type f \( \
    -name 'kafrep*' -o \
    -name '3dcp*' -o \
    -name 'b3dcp*' \
\) -print -delete

If directories exist:

find /var/backups/automysqlbackup -type d \( \
    -name 'kafrep*' -o \
    -name '3dcp*' -o \
    -name 'b3dcp*' \
\) -print -exec rm -rf {} +

6. Slimming /usr

Analyse /usr/share

du -xhd1 /usr/share

The largest components are typically:

  • /usr/share/locale
  • /usr/share/doc
  • /usr/share/man
  • /usr/share/icons
  • /usr/share/fonts
  • /usr/share/nodejs (optional)

Install localepurge (cleanup locales)

apt install localepurge
localepurge

Select languages to keep, e.g.: de, de_AT, en, en_US.

Remove documentation

rm -rf /usr/share/doc/*

Remove manpages

rm -rf /usr/share/man/*

Remove icons and themes (headless)

rm -rf /usr/share/icons/*
rm -rf /usr/share/themes/*

Remove fonts (headless)

rm -rf /usr/share/fonts/*

Remove NodeJS (optional)

Check usage:

which node
node --version
dpkg -l | grep node

If unused:

apt purge nodejs
rm -rf /usr/share/nodejs/*

7. Clean Temporary Files and Rotated Logs

One-liner to clean all rotated logs in all subdirectories of /var/log

find /var/log -type f -name "*.gz" -print -delete
find /var/log -type f -regex ".*\.[0-9]+" -print -delete

rm -rf /tmp/*
rm -f /var/log/*.gz /var/log/*.[0-9]

Clean rotated Apache logs

find /var/log/apache2 -type f -name "*.gz" -print -delete
find /var/log/apache2 -type f -regex ".*\.[0-9]+" -print -delete

Clean rotated NGINX logs

find /var/log/nginx -type f -name "*.gz" -print -delete
find /var/log/nginx -type f -regex ".*\.[0-9]+" -print -delete

Clean rotated APT logs

find /var/log/apt -type f -name "*.gz" -print -delete

Clean rotated unattended-upgrades logs

find /var/log/unattended-upgrades -type f -name "*.gz" -print -delete

If Exim4 is unused:

rm -f /var/log/exim4/*.[0-9]*

rm -rf /tmp/*
rm -f /var/log/*.gz /var/log/*.[0-9]

8. Verify Final Size

du -sh /usr

Optional:

df -h

9. Ready for Incus Migration

Once cleaned, publish or copy the container:

Example: publish to image

incus publish CTNAME --alias slimimage

Copy image to remote server

incus remote add TARGETSERVER
incus copy slimimage TARGETSERVER: --mode=push

End of document.