Sometimes, when you pack a lot of charms, you may end up with lots of wasted space in /var/snap/lxd. For a single charm, you can solve this issue by running charmcraft clean; but what if you have 10, 20, 100 charms?
With the original idea from @sed-i, I wrote a small bash script that cleans up all the LXD instances that are used to pack charms. Two cool features:
--last-used <date>allows you to specify a cutoff time (i.e., “delete the instances that have not been used since<date>”);--dry-runlets you check what would be deleted, without touching any instance.
I use argc to parse input arguments in my bash scripts, so I’ll include both my original script (you’ll need to download argc, but it’s easier to read and modify to your liking) and the “compiled” version (no dependency, but more boilerplate).
Original script (argc dependency)
#!/usr/bin/env bash
# charmcraft-purge
# @describe Delete all the LXC instances that charmcraft creates to pack charms
# @author Luca Bello
# @meta version 0.3
# @meta require-tools lxc,jq
# @option --last-used Delete instances that were last use before this date (format: anything parsed by 'date') (default: one month ago)
# @flag --dry-run Perform a dry run (don't delete instances)
eval "$(argc --argc-eval "$0" "$@")"
# Default --last-used to one week ago (if not specified)
if [[ -z $argc_last_used ]]; then
argc_last_used="$(date -d '-7 days' +'%F')";
else
argc_last_used="$(date -d "$argc_last_used" +'%F')"
fi
lxc_instances=$(lxc list --project=charmcraft --format=json | jq --arg cutoff "$argc_last_used" '[.[] | select(.last_used_at | . < $cutoff)]')
lxc_instances_count=$(echo "$lxc_instances" | jq -r '[ .[] | select(.name | startswith("charmcraft-")) | .name ] | length')
echo "$lxc_instances_count lxc containers will be removed (not used since $argc_last_used)"
for instance in $(echo $lxc_instances | jq -r '.[] | select(.name | startswith("charmcraft-")) | .name'); do
echo "Deleting $instance"
if [ "$argc_dry_run" = 0 ]; then
lxc --project=charmcraft delete "$instance"
fi
done
Compiled script (no dependency, lots of boilerplate)
#!/usr/bin/env bash
# charmcraft-purge
# @describe Delete all the LXC instances that charmcraft creates to pack charms
# @author Luca Bello
# @meta version 0.3
# @meta require-tools lxc,jq
# @option --last-used Delete instances that were last use before this date (format: anything parsed by 'date') (default: one month ago)
# @flag --dry-run Perform a dry run (don't delete instances)
# ARGC-BUILD {
# This block was generated by argc (https://github.com/sigoden/argc).
# Modifying it manually is not recommended
_argc_run() {
if [[ "${1:-}" == "___internal___" ]]; then
_argc_die "error: unsupported ___internal___ command"
fi
if [[ "${OS:-}" == "Windows_NT" ]] && [[ -n "${MSYSTEM:-}" ]]; then
set -o igncr
fi
argc__args=("$(basename "$0" .sh)" "$@")
argc__positionals=()
_argc_index=1
_argc_len="${#argc__args[@]}"
_argc_tools=()
_argc_parse
_argc_require_tools "${_argc_tools[@]}"
if [ -n "${argc__fn:-}" ]; then
$argc__fn "${argc__positionals[@]}"
fi
}
_argc_usage() {
cat <<-'EOF'
charmcraft-purge 0.3
Luca Bello
Delete all the LXC instances that charmcraft creates to pack charms
USAGE: charmcraft-purge [OPTIONS]
OPTIONS:
--last-used <LAST-USED> Delete instances that were last use before this date (format: anything parsed by 'date') (default: one month ago)
--dry-run Perform a dry run (don't delete instances)
-h, --help Print help
-V, --version Print version
EOF
exit
}
_argc_version() {
echo charmcraft-purge 0.3
exit
}
_argc_parse() {
local _argc_key _argc_action
local _argc_subcmds=""
while [[ $_argc_index -lt $_argc_len ]]; do
_argc_item="${argc__args[_argc_index]}"
_argc_key="${_argc_item%%=*}"
case "$_argc_key" in
--help | -help | -h)
_argc_usage
;;
--version | -version | -V)
_argc_version
;;
--)
_argc_dash="${#argc__positionals[@]}"
argc__positionals+=("${argc__args[@]:$((_argc_index + 1))}")
_argc_index=$_argc_len
break
;;
--last-used)
_argc_take_args "--last-used <LAST-USED>" 1 1 "-" ""
_argc_index=$((_argc_index + _argc_take_args_len + 1))
if [[ -z "${argc_last_used:-}" ]]; then
argc_last_used="${_argc_take_args_values[0]:-}"
else
_argc_die "error: the argument \`--last-used\` cannot be used multiple times"
fi
;;
--dry-run)
if [[ "$_argc_item" == *=* ]]; then
_argc_die "error: flag \`--dry-run\` don't accept any value"
fi
_argc_index=$((_argc_index + 1))
if [[ -n "${argc_dry_run:-}" ]]; then
_argc_die "error: the argument \`--dry-run\` cannot be used multiple times"
else
argc_dry_run=1
fi
;;
*)
if _argc_maybe_flag_option "-" "$_argc_item"; then
_argc_die "error: unexpected argument \`$_argc_key\` found"
fi
argc__positionals+=("$_argc_item")
_argc_index=$((_argc_index + 1))
;;
esac
done
_argc_tools=(lxc jq)
if [[ -n "${_argc_action:-}" ]]; then
$_argc_action
else
if [[ "${argc__positionals[0]:-}" == "help" ]] && [[ "${#argc__positionals[@]}" -eq 1 ]]; then
_argc_usage
fi
fi
}
_argc_take_args() {
_argc_take_args_values=()
_argc_take_args_len=0
local param="$1" min="$2" max="$3" signs="$4" delimiter="$5"
if [[ "$min" -eq 0 ]] && [[ "$max" -eq 0 ]]; then
return
fi
local _argc_take_index=$((_argc_index + 1)) _argc_take_value
if [[ "$_argc_item" == *=* ]]; then
_argc_take_args_values=("${_argc_item##*=}")
else
while [[ $_argc_take_index -lt $_argc_len ]]; do
_argc_take_value="${argc__args[_argc_take_index]}"
if _argc_maybe_flag_option "$signs" "$_argc_take_value"; then
if [[ "${#_argc_take_value}" -gt 1 ]]; then
break
fi
fi
_argc_take_args_values+=("$_argc_take_value")
_argc_take_args_len=$((_argc_take_args_len + 1))
if [[ "$_argc_take_args_len" -ge "$max" ]]; then
break
fi
_argc_take_index=$((_argc_take_index + 1))
done
fi
if [[ "${#_argc_take_args_values[@]}" -lt "$min" ]]; then
_argc_die "error: incorrect number of values for \`$param\`"
fi
if [[ -n "$delimiter" ]] && [[ "${#_argc_take_args_values[@]}" -gt 0 ]]; then
local item values arr=()
for item in "${_argc_take_args_values[@]}"; do
IFS="$delimiter" read -r -a values <<<"$item"
arr+=("${values[@]}")
done
_argc_take_args_values=("${arr[@]}")
fi
}
_argc_maybe_flag_option() {
local signs="$1" arg="$2"
if [[ -z "$signs" ]]; then
return 1
fi
local cond=false
if [[ "$signs" == *"+"* ]]; then
if [[ "$arg" =~ ^\+[^+].* ]]; then
cond=true
fi
elif [[ "$arg" == -* ]]; then
if (( ${#arg} < 3 )) || [[ ! "$arg" =~ ^---.* ]]; then
cond=true
fi
fi
if [[ "$cond" == "false" ]]; then
return 1
fi
local value="${arg%%=*}"
if [[ "$value" =~ [[:space:]] ]]; then
return 1
fi
return 0
}
_argc_require_tools() {
local tool missing_tools=()
for tool in "$@"; do
if ! command -v "$tool" >/dev/null 2>&1; then
missing_tools+=("$tool")
fi
done
if [[ "${#missing_tools[@]}" -gt 0 ]]; then
echo "error: missing tools: ${missing_tools[*]}" >&2
exit 1
fi
}
_argc_die() {
if [[ $# -eq 0 ]]; then
cat
else
echo "$*" >&2
fi
exit 1
}
_argc_run "$@"
# ARGC-BUILD }
# Default --last-used to one week ago (if not specified)
if [[ -z $argc_last_used ]]; then
argc_last_used="$(date -d '-7 days' +'%F')";
else
argc_last_used="$(date -d "$argc_last_used" +'%F')"
fi
lxc_instances=$(lxc list --project=charmcraft --format=json | jq --arg cutoff "$argc_last_used" '[.[] | select(.last_used_at | . < $cutoff)]')
lxc_instances_count=$(echo "$lxc_instances" | jq -r '[ .[] | select(.name | startswith("charmcraft-")) | .name ] | length')
echo "$lxc_instances_count lxc containers will be removed (not used since $argc_last_used)"
for instance in $(echo $lxc_instances | jq -r '.[] | select(.name | startswith("charmcraft-")) | .name'); do
echo "Deleting $instance"
if [ "$argc_dry_run" = 0 ]; then
lxc --project=charmcraft delete "$instance"
fi
done
I hope that was useful, enjoy! 
