docker orphaned overlay2 cleanup script

This article presents a Bash script called `docker-overlay-prune.sh` that identifies and removes orphaned overlay2 directories in `/var/lib/docker/overlay2/` which are no longer associated with any Docker image or mounted filesystem. The script runs with dry-run mode by default, only listing unused directories, but includes a `-n` flag to enable actual deletion of those directories.

docker-overlay-prune.sh This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters. Learn more about bidirectional Unicode characters Show hidden characters /bin/bash partly based on https://stackoverflow.com/a/72548686 $ id -u -eq 0 || exec sudo /bin/bash -c "$ printf '%q ' "$BASH SOURCE" "$@" " progname=$ basename $0 quiet=false no dry run=false while getopts ":qn" opt; do case "$opt" in q quiet=true ;; n no dry run=true ;; ? echo "unexpected option ${opt}" echo "usage: ${progname} -q|--quiet " echo " -q: no output" echo " -n: no dry run will remove unused directories " exit 1 ;; esac done shift "$ $OPTIND -1 " ${quiet} = false || exec /bin/bash -c "$ printf '%q ' "$BASH SOURCE" "$@" " /dev/null images= $ docker image ls --all --format "{{.ID}}" mounted=$ mount | grep "/var/lib/docker/overlay2/" dirs= $ find /var/lib/docker/overlay2 -mindepth 1 -maxdepth 1 -type d -not -path ./l -exec basename {} \; unused= echo "Scanning for used overlays2 dirs." for d in "${dirs @ }"; do used=0 dname=${d//"-init"/} check for mounted overlays echo ${mounted} | grep -q ${dname} if $? = 0 ; then continue fi check for overlays being used by images for id in ${images @ }; do docker inspect $id | grep -q $dname if $? = 0 ; then used=1 break fi done if not used add to unused array if ${used} -eq 0 ; then unused+= "${d}" fi done if ${ unused @ } -gt 0 ; then ${no dry run} = true || echo "Could remove: to automatically remove, use the -n, "'"'"no-dry-run"'"'" flag " for d in "${unused @ }"; do if ${no dry run} = true ; then echo "Removing /var/lib/docker/overlay2/${d}" rm -rf /var/lib/docker/overlay2/${d} else echo " /var/lib/docker/overlay2/${d}" fi done echo Done else echo "All overlay2 directories are used, nothing to clean up." fi