hygienic-books
942128c89f
Parse the APT package action protocol and classify records by operation. Use the package list to determine important and trivial snapshot chains, then generate collision-resistant names containing shortened package data. Select ZFS datasets through the configured property or explicit roots. Create recursive snapshots atomically, support dry-run output, and prune old snapshots from the matching retention chain after success. Preserve the original warning-oriented behavior by reporting snapshot and retention failures without aborting the package operation.
222 lines
8.1 KiB
Bash
222 lines
8.1 KiB
Bash
#!/bin/bash
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set -o pipefail
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declare -r config_file='/etc/apt-zfs-snapshot.conf'
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declare -r zfs_property='space.quico:auto-snapshot'
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declare -r zfs_property_value='true'
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declare -r zfs_max_name_length=255
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if [[ -r "${config_file}" ]]; then
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# shellcheck disable=SC1090
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source "${config_file}"
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fi
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dry_run="${dry_run:-false}"
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important_names="${important_names:-linux-image(-.*)?|linux-headers(-.*)?|systemd|zfs-(dkms|utils)}"
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snapshots_trivial_keep="${snapshots_trivial_keep:-25}"
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snapshots_important_keep="${snapshots_important_keep:-10}"
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trivial_suffix="${trivial_suffix:-trv}"
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important_suffix="${important_suffix:-imp}"
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packages_max_length="${packages_max_length:-30}"
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snap_only_local_datasets="${snap_only_local_datasets:-true}"
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snapshot_roots="${snapshot_roots:-}"
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field_separator="${field_separator:-_}"
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snapshot_prefix="${snapshot_prefix:-apt}"
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date_format="${date_format:-%F-%H%M}"
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timezone="${timezone:-Etc/UTC}"
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install_suffix="${install_suffix:-inst}"
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remove_suffix="${remove_suffix:-rmvl}"
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upgrade_suffix="${upgrade_suffix:-upgr}"
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downgrade_suffix="${downgrade_suffix:-down}"
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mixed_suffix="${mixed_suffix:-mixd}"
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package_separator="${package_separator:-:}"
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declare -a packages operations
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print_msg() {
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local level="$1" message="$2"
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printf '[%s] %s\n' "${level}" "${message}" >&2
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}
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add_package() {
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local package="$1" operation="$2"
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[[ -n "${package}" ]] || return 0
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packages+=("${package//+/_}")
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operations+=("${operation}")
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}
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parse_apt_input() {
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local fd="${APT_HOOK_INFO_FD:-0}" line package old_version direction new_version action
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local protocol='1' in_records='false'
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while IFS= read -r line <&"${fd}"; do
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if [[ "${line}" == VERSION\ * ]]; then
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protocol="${line#VERSION }"
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continue
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fi
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if [[ "${protocol}" == '1' && -n "${line}" ]]; then
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package="${line##*/}"
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package="${package%.deb}"
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package="${package%_*_*}"
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add_package "${package}" 'install'
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continue
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fi
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if [[ "${in_records}" != 'true' ]]; then
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[[ -z "${line}" ]] && in_records='true'
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continue
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fi
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if [[ "${protocol}" == '1' ]]; then
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package="${line##*/}"
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package="${package%.deb}"
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package="${package%_*_*}"
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add_package "${package}" 'install'
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continue
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fi
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read -r package old_version _old_arch direction new_version _new_arch _multiarch action <<<"${line}"
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[[ -n "${package}" ]] || continue
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if [[ "${action}" == '**REMOVE**' ]]; then
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add_package "${package}" 'remove'
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elif [[ "${direction}" == '>' ]]; then
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add_package "${package}" 'downgrade'
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elif [[ "${old_version}" == '-' ]]; then
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add_package "${package}" 'install'
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elif [[ "${direction}" == '<' ]]; then
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add_package "${package}" 'upgrade'
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fi
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done
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}
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get_datasets() {
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local dataset value
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if [[ -n "${snapshot_roots}" ]]; then
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read -r -a snappable_datasets <<<"${snapshot_roots}"
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return 0
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fi
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while IFS=$'\t' read -r dataset value; do
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[[ "${value}" == "${zfs_property_value}" && "${dataset}" != *@* ]] || continue
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if [[ "${snap_only_local_datasets}" != 'true' ]] || findmnt -rn -t zfs -o SOURCE | grep -Fxq -- "${dataset}"; then
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snappable_datasets+=("${dataset}")
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fi
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done < <(zfs get -H -o name,value "${zfs_property}")
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}
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operation_suffix() {
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local -A seen=()
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local operation
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for operation in "${operations[@]}"; do seen["${operation}"]=1; done
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if (( ${#seen[@]} > 1 )); then printf '%s' "${mixed_suffix}"; return; fi
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case "${operations[0]:-upgrade}" in
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install) printf '%s' "${install_suffix}" ;;
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remove) printf '%s' "${remove_suffix}" ;;
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downgrade) printf '%s' "${downgrade_suffix}" ;;
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*) printf '%s' "${upgrade_suffix}" ;;
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esac
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}
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severity_and_packages() {
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local package important='false'
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local -a important_packages trivial_packages
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for package in "${packages[@]}"; do
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if grep -Piq -- "^(${important_names})$" <<<"${package}"; then
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important_packages+=("${package}")
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important='true'
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else
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trivial_packages+=("${package}")
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fi
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done
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if [[ "${important}" == 'true' ]]; then
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severity="${important_suffix}"
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package_list="$(IFS="${package_separator}"; printf '%s' "${important_packages[*]}")"
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[[ -n "${trivial_packages[*]}" ]] && package_list+="${package_separator}$(IFS="${package_separator}"; printf '%s' "${trivial_packages[*]}")"
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else
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severity="${trivial_suffix}"
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package_list="$(IFS="${package_separator}"; printf '%s' "${trivial_packages[*]}")"
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fi
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}
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shorten_packages() {
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local value="${package_list}" limit="${packages_max_length}" dataset fixed_length available
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for dataset in "${snappable_datasets[@]}"; do
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fixed_length="${#dataset}"
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fixed_length=$((fixed_length + 1 + ${#snapshot_prefix} + ${#field_separator} + ${#date_string} + ${#field_separator} + 10 + ${#field_separator} + 4 + ${#severity} + ${#field_separator} + 5))
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available=$((zfs_max_name_length - fixed_length))
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(( available < limit )) && limit="${available}"
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done
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(( limit < 0 )) && limit=0
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(( limit > 0 )) || { package_list=''; return; }
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while (( ${#value} > limit )) && [[ "${value}" == *"${package_separator}"* ]]; do
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value="${value%"${package_separator}"*}"
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done
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if (( ${#value} > limit )); then
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if (( limit <= 3 )); then value="${value:0:limit}"; else value="${value:0:limit-3}..."; fi
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fi
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package_list="${value}"
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}
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existing_snapshot() { zfs list -H -t snapshot -o name | grep -Fxq -- "$1"; }
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make_snapshot_name() {
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local counter="$1" dataset base
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names=()
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for dataset in "${snappable_datasets[@]}"; do
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base="${dataset}@${snapshot_prefix}${field_separator}${date_string}${field_separator}${counter}${field_separator}op:$(operation_suffix)${field_separator}sev:${severity}${field_separator}pkgs:${package_list}"
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(( ${#base} <= zfs_max_name_length )) || { print_msg ERR "Snapshot name exceeds ${zfs_max_name_length} characters: ${base}"; return 2; }
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names+=("${base}")
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existing_snapshot "${base}" && return 1
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done
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}
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prune_snapshots() {
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local dataset limit name count
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[[ "${dry_run}" == 'true' ]] && return 0
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limit="${snapshots_trivial_keep}"
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[[ "${severity}" == "${important_suffix}" ]] && limit="${snapshots_important_keep}"
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for dataset in "${snappable_datasets[@]}"; do
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# Query only the root dataset. Destroying its recursive snapshot also
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# removes the matching descendant snapshots as one snapshot tree.
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mapfile -t snapshots < <(zfs list -H -t snapshot -o name -s creation "${dataset}" | grep -F "${dataset}@${snapshot_prefix}${field_separator}" | grep -F "${field_separator}sev:${severity}${field_separator}")
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count="${#snapshots[@]}"
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while (( count > limit )); do
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name="${snapshots[0]}"
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zfs destroy -r "${name}" || { print_msg WARN "Failed to destroy ${name}"; break; }
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snapshots=("${snapshots[@]:1}")
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((count--))
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print_msg INFO "Destroyed old snapshot ${name}"
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done
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done
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}
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main() {
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local counter=0
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parse_apt_input
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(( ${#packages[@]} > 0 )) || { print_msg INFO 'No package actions received; skipping snapshot'; return 0; }
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get_datasets
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(( ${#snappable_datasets[@]} > 0 )) || { print_msg INFO "No eligible ZFS datasets; skipping snapshot"; return 0; }
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date_string="$(TZ="${timezone}" date +"${date_format}")"
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severity_and_packages
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shorten_packages
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while :; do
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make_snapshot_name "$((++counter))"
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case "$?" in
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0) break ;;
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1) ;;
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*) return 1 ;;
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esac
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done
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if [[ "${dry_run}" == 'true' ]]; then
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printf '[INFO] Dry-run, would create:\n' >&2
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printf ' %s\n' "${names[@]}" >&2
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return 0
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fi
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zfs snapshot -r "${names[@]}" || { print_msg WARN 'ZFS snapshot failed'; return 0; }
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printf '[INFO] Created ZFS snapshots:\n' >&2
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printf ' %s\n' "${names[@]}" >&2
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prune_snapshots
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}
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main
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