absolute-dotfiles/.local/bin/docker-nuke

#!/usr/bin/env bash
# docker-nuke — capture diagnostics from a wedged Docker Desktop, then
# force-kill and restart it.
#
# Written for bash 3.2 compatibility (macOS /bin/bash).

set -euo pipefail

# --- configuration ----------------------------------------------------------
#
# The SC2034 directives below are per-line on purpose, not file-level: each
# constant is consumed by a later task, and its directive is deleted at that
# point. A file-level disable would silence SC2034 for the whole file forever,
# hiding a genuinely dead variable added later. By the final task none of these
# directives should remain.

HEALTH_TIMEOUT=6        # seconds to wait on `docker info` before calling it wedged
GRACEFUL_WAIT=8         # seconds to let Docker quit politely
TERM_WAIT=5             # seconds to wait after SIGTERM before SIGKILL
# Bounded number of "fresh docker_pids -> SIGKILL -> settle" rounds run if a
# post-SIGKILL scan still finds live Docker processes. A supervisor such as
# com.docker.backend can respawn a killed helper under a brand new pid the
# entry snapshot never knew about, so this must be a real cap, never an
# unbounded loop, or a respawning Docker could hang this tool forever.
KILL_RETRY_ROUNDS=3
RESTART_TIMEOUT=90      # seconds to wait for the daemon to come back
POLL_INTERVAL=2         # seconds between daemon health polls
SAMPLE_DURATION=2       # seconds of stack sampling per process
SAMPLE_TIMEOUT=10       # hard cap on a single `sample` invocation
DUMP_RETENTION=10       # how many dump directories to keep
LOG_TAIL_LINES=2000     # lines of Docker log to copy (keeps dumps small)
LOG_CAPTURE_TIMEOUT=20  # hard cap on the whole capture_logs step
CRASH_CAPTURE_TIMEOUT=10 # hard cap on the whole capture_crashes step

DOCKER_APP="/Applications/Docker.app"
# The bundle path above cannot substitute for the AppleScript app name below:
# the running GUI application is the nested "Contents/MacOS/Docker
# Desktop.app", whose CFBundleName is "Docker Desktop", not the top-level
# bundle path. Both are genuinely needed; this constant exists only so the
# two literal identities for the same app cannot drift apart silently.
DOCKER_APP_NAME="Docker Desktop"
DOCKER_LOG_DIR="$HOME/Library/Containers/com.docker.docker/Data/log"
DOCKER_RAW="$HOME/Library/Containers/com.docker.docker/Data/vms/0/data/Docker.raw"
CRASH_DIR="$HOME/Library/Logs/DiagnosticReports"

# Overridable so tests never touch real state.
DUMP_ROOT="${DOCKER_NUKE_DUMP_ROOT:-$HOME/.local/state/docker-nuke}"

OPT_FORCE=0
OPT_NO_RESTART=0
OPT_DRY_RUN=0
OPT_DEEP=0

# --- helpers ----------------------------------------------------------------

bin_exists() { command -v "$1" >/dev/null 2>&1; }

# Run a command with a hard time limit. Returns 124 if it timed out.
# Call inside a conditional so `set -e` does not abort on a non-zero return.
run_timeout() {
  local secs="$1"
  shift
  # A shell function (e.g. disk_report) has no PATH-resolvable executable, so
  # an external timeout/gtimeout binary can never exec it directly (execvp
  # fails with rc=127). Route those straight to the pure-bash poller below,
  # which runs the command in this same shell instead of a child process.
  if bin_exists timeout && ! declare -F "$1" >/dev/null 2>&1; then
    timeout "$secs" "$@"
    return $?
  fi
  if bin_exists gtimeout && ! declare -F "$1" >/dev/null 2>&1; then
    gtimeout "$secs" "$@"
    return $?
  fi

  # Pure-bash fallback: run in background and poll.
  "$@" &
  local pid=$!
  local waited=0
  while kill -0 "$pid" 2>/dev/null; do
    if [ "$waited" -ge "$secs" ]; then
      kill -9 "$pid" 2>/dev/null || true
      wait "$pid" 2>/dev/null || true
      return 124
    fi
    sleep 1
    waited=$((waited + 1))
  done
  local rc=0
  wait "$pid" || rc=$?
  return "$rc"
}

# Exact process names to target, in addition to anything under Docker.app.
# NOTE: never use `pgrep -f docker` here — it matches this script's own
# command line and the tool would kill itself.
DOCKER_PROC_NAMES="com.docker.backend com.docker.build com.docker.krun \
com.docker.vpnkit com.docker.virtualization vpnkit docker"

docker_pids() {
  local self="$$"
  local parent="${PPID:-0}"
  local name pid comm
  {
    # `pgrep -f "$DOCKER_APP"` matches any process whose *command line*
    # mentions the bundle path — e.g. `tail -f /Applications/Docker.app/...`
    # matches even though that process is plainly not Docker. Post-filter
    # each candidate by its actual executable so only processes truly
    # launched from the bundle survive. Wrapped in `|| true`: under
    # `set -o pipefail`, an empty `pgrep -f` match (exit 1) would otherwise
    # make this whole statement fail and abort the function under `set -e`.
    pgrep -f "$DOCKER_APP" 2>/dev/null | while read -r pid; do
      if [ -z "$pid" ]; then continue; fi
      # A dead PID (process exited between pgrep and ps) or a `ps` failure
      # must yield an empty comm, which matches no case branch below —
      # never a crash, never a false positive.
      # NOTE: `ps -o comm=` reports the executable path as invoked, not
      # canonicalized — a Docker helper ever exec'd by relative path or bare
      # name would report a non-bundle comm here and be silently dropped.
      comm="$(ps -o comm= -p "$pid" 2>/dev/null)" || true
      case "$comm" in
        "$DOCKER_APP"/*) printf '%s\n' "$pid" ;;
      esac
    done || true

    # Exact-name matches are already precise — do NOT apply the comm
    # filter here. One job of this branch is catching a hung
    # /usr/local/bin/docker CLI, which legitimately lives outside the
    # bundle; filtering by $DOCKER_APP prefix would break that.
    for name in $DOCKER_PROC_NAMES; do
      pgrep -x "$name" 2>/dev/null || true
    done
  } | sort -un | while read -r pid; do
    if [ -z "$pid" ]; then continue; fi
    if [ "$pid" = "$self" ]; then continue; fi
    if [ "$pid" = "$parent" ]; then continue; fi
    printf '%s\n' "$pid"
  done
}

# Returns 0 if the daemon answers within HEALTH_TIMEOUT, else non-zero
# (124 specifically means it hung rather than errored).
docker_healthy() {
  local rc=0
  run_timeout "$HEALTH_TIMEOUT" docker info >/dev/null 2>&1 || rc=$?
  return "$rc"
}

DUMP_DIR=""
CAPTURE_FAILURES=""

# new_dump_dir — create and print a fresh timestamped directory under
# DUMP_ROOT. This is the one place in the dump path that fails loudly: if the
# directory cannot be created there is nowhere left to record a failure, so
# the caller must find out immediately rather than have every later capture
# silently write into a path that never existed.
new_dump_dir() {
  local stamp dir
  stamp="$(date -u '+%Y%m%dT%H%M%SZ')"
  dir="$DUMP_ROOT/$stamp"
  if ! mkdir -p "$dir" 2>/dev/null; then
    warn "docker-nuke: could not create dump directory $dir (dump root unwritable or full)"
    return 1
  fi
  printf '%s\n' "$dir"
}

# capture NAME SECONDS CMD... — write CMD output to $DUMP_DIR/NAME.
# Never fails: a timeout or error is recorded and execution continues, so a
# broken capture can never block recovery.
capture() {
  local name="$1" secs="$2"
  shift 2
  local out="$DUMP_DIR/$name"
  local rc=0
  run_timeout "$secs" "$@" >"$out" 2>&1 || rc=$?
  if [ "$rc" -ne 0 ]; then
    # The banner append itself must never be able to trip set -e: on an
    # unwritable or full dump root this redirection fails too, and without
    # the guard that failure -- not the original capture failure -- would be
    # what aborts the entire dump at the very first capture.
    printf '\n[docker-nuke] capture "%s" failed or timed out (rc=%s)\n' "$name" "$rc" >>"$out" 2>/dev/null || true
    CAPTURE_FAILURES="$CAPTURE_FAILURES $name"
  fi
  return 0
}

# Sample user-space stacks of the daemon-side processes. This is the one
# signal that cannot be reconstructed after the processes are killed.
capture_samples() {
  if ! bin_exists sample; then
    printf 'sample(1) not available\n' >"$DUMP_DIR/samples-skipped.txt"
    return 0
  fi
  local name pid
  for name in com.docker.backend com.docker.krun; do
    for pid in $(pgrep -x "$name" 2>/dev/null || true); do
      capture "sample-$name-$pid.txt" "$SAMPLE_TIMEOUT" \
        sample "$pid" "$SAMPLE_DURATION" -mayDie
    done
  done
}

capture_logs() {
  mkdir -p "$DUMP_DIR/logs"
  local f base
  for f in "$DOCKER_LOG_DIR"/host/*.log "$DOCKER_LOG_DIR"/vm/*.log; do
    if [ -f "$f" ]; then
      base="$(basename "$f")"
      tail -n "$LOG_TAIL_LINES" "$f" >"$DUMP_DIR/logs/$base" 2>/dev/null || true
    fi
  done
}

capture_crashes() {
  mkdir -p "$DUMP_DIR/crashes"
  if [ ! -d "$CRASH_DIR" ]; then
    return 0
  fi
  local f
  # grep exits 1 when no crash report matches (the common case: this dump
  # feature is expected to run against a healthy history most of the time).
  # Under `set -o pipefail` that would fail the whole pipeline and abort
  # run_dump via `set -e`. Group it with `|| true` so a clean "no matches"
  # never propagates as a pipeline failure.
  #
  # Grouping only the grep is not enough on its own: `head -5` closes its
  # read end once it has 5 lines, so with more than 5 matches upstream
  # `ls -1t` is later killed by SIGPIPE (rc=141) instead of exiting 0; an
  # unreadable CRASH_DIR gives `ls` rc=2 the same way. Either propagates as
  # this pipeline's exit status under pipefail and would abort the dump via
  # `set -e`, so the trailing `|| true` guards the pipeline as a whole, not
  # just the grep.
  # shellcheck disable=SC2012  # crash report names are macOS-generated, never contain newlines; ls -t gives the mtime order find cannot without extra plumbing
  ls -1t "$CRASH_DIR" 2>/dev/null | { grep -i docker || true; } | head -5 | while IFS= read -r f; do
    cp "$CRASH_DIR/$f" "$DUMP_DIR/crashes/" 2>/dev/null || true
  done || true
}

disk_report() {
  df -h
  printf '\n--- Docker.raw ---\n'
  ls -lh "$DOCKER_RAW" 2>/dev/null || printf 'Docker.raw not found\n'
  du -h -d0 "$DOCKER_RAW" 2>/dev/null || true
}

socket_report() {
  local sock="$HOME/.docker/run/docker.sock"
  printf 'socket: %s\n' "$sock"
  ls -l "$sock" 2>/dev/null || printf 'socket does not exist\n'
  printf '\n--- listeners ---\n'
  lsof "$sock" 2>/dev/null || printf 'no processes hold the socket\n'
}

run_dump() {
  local rc
  # DUMP_DIR is reset to empty first so a failed new_dump_dir never leaves it
  # pointing at a directory that does not exist (Fix 1). new_dump_dir is the
  # one place in this path that is allowed to fail loudly: on an unwritable
  # or full dump root it has already logged why via `warn` and returned
  # non-zero, and there is nowhere left to record a capture failure, so
  # run_dump stops here -- before any capture runs -- rather than limping
  # into the first capture and dying mid-dump.
  DUMP_DIR=""
  DUMP_DIR="$(new_dump_dir)" || return 1
  CAPTURE_FAILURES=""
  log "docker-nuke: capturing diagnostics to $DUMP_DIR"

  capture "ps.txt" 10 ps -eo pid,ppid,stat,%cpu,%mem,etime,command
  capture "docker-info.txt" "$HEALTH_TIMEOUT" docker info
  capture "docker-version.txt" "$HEALTH_TIMEOUT" docker version
  capture "disk.txt" 15 disk_report
  capture "memory.txt" 10 vm_stat
  capture "socket.txt" 10 socket_report

  # capture_logs and capture_crashes write files directly rather than
  # emitting stdout, so they are not routed through capture() (which would
  # redirect stdout to a single named artifact). They still must be
  # time-bounded like every other step, and run_timeout's `declare -F` guard
  # (see run_timeout above) routes them to the pure-bash poller since neither
  # is a PATH-resolvable executable. A timeout or error is recorded into
  # CAPTURE_FAILURES the same way capture() records one, so a wedged
  # filesystem here cannot hang the dump either.
  rc=0
  run_timeout "$LOG_CAPTURE_TIMEOUT" capture_logs || rc=$?
  if [ "$rc" -ne 0 ]; then
    CAPTURE_FAILURES="$CAPTURE_FAILURES logs"
  fi

  rc=0
  run_timeout "$CRASH_CAPTURE_TIMEOUT" capture_crashes || rc=$?
  if [ "$rc" -ne 0 ]; then
    CAPTURE_FAILURES="$CAPTURE_FAILURES crashes"
  fi

  capture_samples
}

prune_dumps() {
  local keep="${1:-$DUMP_RETENTION}"
  if [ ! -d "$DUMP_ROOT" ]; then
    return 0
  fi
  local d
  # An unreadable DUMP_ROOT gives `ls` a non-zero exit, which -- since this
  # pipeline is prune_dumps' last statement and therefore its return value --
  # would otherwise abort a `set -e` caller. The trailing `|| true` matches
  # the guard used in capture_crashes for the same class of problem; the
  # normal-path behavior (prune the oldest, keep $keep newest) is unchanged.
  # shellcheck disable=SC2012  # dump dir names are our own generated timestamps, never contain newlines; sort -r needs plain lines, not find -print0
  ls -1 "$DUMP_ROOT" 2>/dev/null | sort -r | tail -n "+$((keep + 1))" | while IFS= read -r d; do
    if [ -n "$d" ]; then
      rm -rf "${DUMP_ROOT:?}/$d"
    fi
  done || true
  return 0
}

pids_alive() {
  local pid alive="" stat
  for pid in "$@"; do
    if kill -0 "$pid" 2>/dev/null; then
      # kill -0 succeeds against a zombie (state Z, <defunct>): the process
      # table entry is still there but the process has already exited and is
      # only waiting for its parent to reap it. Treat that as dead so a slow
      # reaper can never manufacture a spurious "survived SIGKILL" report
      # (Fix 7). ps -o stat= can print extra flag letters after the primary
      # state letter (e.g. Z+), so match a leading Z rather than equality.
      stat="$(ps -o stat= -p "$pid" 2>/dev/null)" || true
      case "$stat" in
        Z*) : ;;
        *) alive="$alive $pid" ;;
      esac
    fi
  done
  printf '%s' "${alive# }"
}

kill_pids() {
  local sig="$1"
  shift
  local pid
  for pid in "$@"; do
    kill "-$sig" "$pid" 2>/dev/null || true
  done
  return 0
}

# Returns 0 once every PID is gone, 1 if SECONDS elapses first.
wait_for_exit() {
  local secs="$1"
  shift
  local waited=0
  while [ "$waited" -lt "$secs" ]; do
    if [ -z "$(pids_alive "$@")" ]; then
      return 0
    fi
    sleep 1
    waited=$((waited + 1))
  done
  if [ -z "$(pids_alive "$@")" ]; then
    return 0
  fi
  return 1
}

# Stop root launchd helpers. Only called with --deep; needs a cached sudo
# credential.
stop_privileged_helpers() {
  log "docker-nuke: stopping privileged helpers (sudo required)"
  # -n (non-interactive) never prompts: sudo writes "Password:" to stderr but
  # reads the answer from /dev/tty, so with stderr discarded and no cached
  # credential a plain `sudo` blocks forever with no visible prompt -- and by
  # the time this runs, Docker has already been SIGKILLed (Fix 3). -n instead
  # fails fast into the warning below.
  if ! sudo -n launchctl stop com.docker.vmnetd 2>/dev/null; then
    warn "docker-nuke: sudo -n failed for com.docker.vmnetd (no cached credential, or not permitted); skipping"
  fi
  if ! sudo -n launchctl stop com.docker.socket 2>/dev/null; then
    warn "docker-nuke: sudo -n failed for com.docker.socket (no cached credential, or not permitted); skipping"
  fi
}

# Three-stage escalation: polite quit, SIGTERM, SIGKILL.
#
# Success at every stage is decided from a FRESH docker_pids scan, never from
# the entry snapshot below or from wait_for_exit's own return value (Fix 1).
# wait_for_exit still runs against the snapshot at each stage for TIMING --
# it correctly answers "did the ones we signalled exit" -- but it cannot see
# a Docker process that appeared after the snapshot was taken, so it can
# never be trusted alone to answer "is Docker gone". Concretely:
# com.docker.backend supervises helpers; SIGKILL order is numeric (sort -un
# in docker_pids), unrelated to the supervision tree. A helper can be killed,
# the still-alive backend respawns it under a NEW pid, then the backend
# itself is killed. Every snapshot pid is now gone, but the respawned helper
# is still running -- only a fresh docker_pids call can see it.
nuke_docker() {
  local pids fresh
  pids="$(docker_pids | tr '\n' ' ')"
  if [ -z "$pids" ]; then
    log "docker-nuke: no Docker processes found"
    return 0
  fi

  log "docker-nuke: asking Docker Desktop to quit"
  osascript -e 'quit app "'"$DOCKER_APP_NAME"'"' >/dev/null 2>&1 || true
  # shellcheck disable=SC2086  # $pids must word-split into separate PID arguments here
  wait_for_exit "$GRACEFUL_WAIT" $pids || true
  fresh="$(docker_pids | tr '\n' ' ')"
  if [ -z "$fresh" ]; then
    log "docker-nuke: Docker exited cleanly"
    return 0
  fi

  # Narrow to the subset still alive from the entry snapshot before
  # signalling (Fix 8): a pid that already exited during the graceful-quit
  # wait must never be re-signalled, at this stage or the next.
  local snapshot_alive
  # shellcheck disable=SC2086  # $pids must word-split into separate PID arguments here
  snapshot_alive="$(pids_alive $pids)"

  log "docker-nuke: sending SIGTERM"
  # shellcheck disable=SC2086  # $snapshot_alive must word-split into separate PID arguments here
  kill_pids TERM $snapshot_alive
  # shellcheck disable=SC2086  # $snapshot_alive must word-split into separate PID arguments here
  wait_for_exit "$TERM_WAIT" $snapshot_alive || true
  fresh="$(docker_pids | tr '\n' ' ')"
  if [ -z "$fresh" ]; then
    log "docker-nuke: Docker exited after SIGTERM"
    return 0
  fi

  log "docker-nuke: sending SIGKILL"
  local remaining
  # shellcheck disable=SC2086  # $snapshot_alive must word-split into separate PID arguments here
  remaining="$(pids_alive $snapshot_alive)"
  # shellcheck disable=SC2086  # $remaining must word-split into separate PID arguments here
  kill_pids KILL $remaining
  sleep 1

  if [ "${OPT_DEEP:-0}" -eq 1 ]; then
    stop_privileged_helpers
  fi

  # Bounded respawn retry (Fix 1): if a fresh scan still finds live Docker
  # processes, SIGKILL exactly that fresh set, let it settle, and scan again.
  # Capped at KILL_RETRY_ROUNDS -- never an unbounded loop -- so a Docker
  # that keeps respawning helpers cannot hang this tool forever.
  local round=0
  fresh="$(docker_pids | tr '\n' ' ')"
  while [ -n "$fresh" ]; do
    round=$((round + 1))
    if [ "$round" -gt "$KILL_RETRY_ROUNDS" ]; then
      break
    fi
    warn "docker-nuke: Docker processes still present after SIGKILL, retrying (round $round of $KILL_RETRY_ROUNDS): $fresh"
    # shellcheck disable=SC2086  # $fresh must word-split into separate PID arguments here
    kill_pids KILL $fresh
    sleep 1
    fresh="$(docker_pids | tr '\n' ' ')"
  done

  if [ -n "$fresh" ]; then
    warn "docker-nuke: processes survived SIGKILL: $fresh"
    return 1
  fi
  log "docker-nuke: all Docker processes terminated"
  return 0
}

start_docker() {
  log "docker-nuke: relaunching Docker Desktop"
  open -a Docker >/dev/null 2>&1 || open "$DOCKER_APP" >/dev/null 2>&1 || true
}

# Returns 0 once the daemon answers, 1 if SECONDS elapses first.
#
# The deadline is wall-clock, not a count of sleeps (Fix 2, review round 1).
# docker_healthy can itself cost up to HEALTH_TIMEOUT per call (it runs
# run_timeout "$HEALTH_TIMEOUT" docker info internally), but the old version
# of this loop only ever accumulated POLL_INTERVAL in `waited`, silently
# discounting docker_healthy's own cost every single iteration. Against a
# genuinely wedged daemon that undercount compounds per iteration: with real
# constants (HEALTH_TIMEOUT=6, POLL_INTERVAL=2) an 8s request measured 32s
# wall clock (4x), and the RESTART_TIMEOUT=90 caller could overshoot to
# roughly 6 minutes. Capturing a start time and checking `now - start`
# before each docker_healthy call instead bounds the overshoot to at most
# one in-flight docker_healthy call, never a per-iteration multiplier.
wait_for_daemon() {
  local secs="$1"
  local start now
  start="$(date +%s)"
  while :; do
    now="$(date +%s)"
    if [ "$((now - start))" -ge "$secs" ]; then
      return 1
    fi
    if docker_healthy; then
      return 0
    fi
    sleep "$POLL_INTERVAL"
  done
}

# write_summary VERDICT ELAPSED — record the triage payload the user reads
# after recovery. Must never abort the caller, on ANY path (Fix 1, review
# round 1): a no-op when DUMP_DIR is unset, empty, or not a directory (e.g.
# after new_dump_dir failed on a full disk) -- and the write itself is
# guarded too, since the disk can fill AFTER new_dump_dir already created a
# valid DUMP_DIR but BEFORE this function runs; an unwritable or full
# DUMP_DIR at write time is exactly the scenario this tool exists to
# survive. The redirection is nested inside an outer group so the outer
# group's own 2>/dev/null is already in effect before the inner redirection
# is attempted -- a single-level `{ ... } >file 2>/dev/null` does NOT
# suppress bash's own "cannot create" diagnostic, since bash reports that
# failure before the trailing 2>/dev/null on the same command takes effect.
# A write failure is logged via warn and swallowed, never propagated.
write_summary() {
  local verdict="$1" elapsed="$2" rc=0
  local cf="${CAPTURE_FAILURES:-}"
  if [ -z "$cf" ]; then cf=" none"; fi
  if [ -z "${DUMP_DIR:-}" ] || [ ! -d "${DUMP_DIR:-}" ]; then
    return 0
  fi
  {
    {
      printf 'docker-nuke summary\n'
      printf '===================\n\n'
      printf 'verdict:          %s\n' "$verdict"
      printf 'elapsed seconds:  %s\n' "$elapsed"
      printf 'dump directory:   %s\n' "$DUMP_DIR"
      printf 'capture failures:%s\n' "$cf"
      printf '\nTriage hints\n------------\n'
      printf '* ps.txt      STAT column: U or D means stuck in the kernel, not user space\n'
      printf '* disk.txt    a full or near-full data volume is a common cause of a wedged daemon -- check free space on the volume backing Docker.raw (df -h) and clear it, or raise the disk image limit in Docker Desktop Settings, before relaunching\n'
      printf '* sample-*    user-space stacks showing where the daemon was stuck\n'
      printf '* logs/       Docker host and vm logs from just before the kill\n'
    } >"$DUMP_DIR/summary.txt"
  } 2>/dev/null || rc=$?
  if [ "$rc" -ne 0 ]; then
    warn "docker-nuke: could not write summary to $DUMP_DIR/summary.txt (dump directory unwritable or full)"
  fi
  return 0
}

log()  { printf '%s\n' "$*"; }
warn() { printf '%s\n' "$*" >&2; }

usage() {
  cat <<'EOF'
docker-nuke: force-restart a wedged Docker Desktop, capturing diagnostics first

Usage:
  docker-nuke [options]

Options:
  -f, --force        Skip the confirmation shown when Docker looks healthy
  -n, --no-restart   Kill Docker but do not relaunch it
      --dry-run      Report what would be killed and dumped; change nothing
      --deep         Also stop root launchd helpers (com.docker.vmnetd); needs sudo
  -h, --help         Show this help

Diagnostics are written to ~/.local/state/docker-nuke/<timestamp>/ before
anything is killed. The most recent 10 dumps are kept.

Exit codes:
  0  Docker killed and confirmed responsive again
  1  Daemon did not come back within the restart timeout
  2  Usage error, or aborted at the healthy-daemon prompt
EOF
}

parse_args() {
  OPT_FORCE=0
  OPT_NO_RESTART=0
  OPT_DRY_RUN=0
  OPT_DEEP=0
  while [ "$#" -gt 0 ]; do
    case "$1" in
      -f|--force)      OPT_FORCE=1 ;;
      -n|--no-restart) OPT_NO_RESTART=1 ;;
      --dry-run)       OPT_DRY_RUN=1 ;;
      --deep)          OPT_DEEP=1 ;;
      -h|--help)       usage; return 3 ;;
      *)
        warn "docker-nuke: unknown option '$1'"
        usage >&2
        return 2
        ;;
    esac
    shift
  done
  return 0
}

# --- entrypoint -------------------------------------------------------------

confirm_healthy_nuke() {
  local info
  info="$(run_timeout "$HEALTH_TIMEOUT" docker info \
    --format '{{.ServerVersion}} ({{.ContainersRunning}} running)' 2>/dev/null || true)"
  log "docker-nuke: Docker looks healthy: ${info:-unknown}"
  log "Nuking will stop running containers."
  printf 'Proceed anyway? [y/N] '
  local reply=""
  read -r reply || true
  case "$reply" in
    y|Y|yes|YES) return 0 ;;
    *) log "docker-nuke: aborted"; return 2 ;;
  esac
}

dry_run_report() {
  local pids
  pids="$(docker_pids | tr '\n' ' ')"
  log "docker-nuke: DRY RUN — no changes made"
  if [ -z "$pids" ]; then
    log "  would kill: (no Docker processes found)"
  else
    log "  would kill: $pids"
    # shellcheck disable=SC2086
    ps -o pid,stat,%cpu,%mem,etime,comm -p $pids 2>/dev/null || true
  fi
  log "  would dump to: $DUMP_ROOT/<timestamp>"
  if [ "$OPT_NO_RESTART" -eq 1 ]; then
    log "  would not restart Docker (--no-restart)"
  else
    log "  would restart Docker and wait up to ${RESTART_TIMEOUT}s"
  fi
}

main() {
  local rc=0
  parse_args "$@" || rc=$?
  if [ "$rc" -eq 3 ]; then return 0; fi
  if [ "$rc" -ne 0 ]; then return "$rc"; fi

  if [ "$OPT_DRY_RUN" -eq 1 ]; then
    dry_run_report
    return 0
  fi

  if docker_healthy && [ "$OPT_FORCE" -eq 0 ]; then
    confirm_healthy_nuke || return 2
  fi

  local started elapsed verdict
  started="$(date +%s)"

  run_dump
  nuke_docker || true

  if [ "$OPT_NO_RESTART" -eq 1 ]; then
    verdict="killed, not restarted (--no-restart)"
    elapsed=$(( $(date +%s) - started ))
    write_summary "$verdict" "$elapsed"
    prune_dumps
    log "docker-nuke: $verdict"
    log "docker-nuke: diagnostics in $DUMP_DIR"
    return 0
  fi

  start_docker
  if wait_for_daemon "$RESTART_TIMEOUT"; then
    verdict="recovered"
    elapsed=$(( $(date +%s) - started ))
    write_summary "$verdict" "$elapsed"
    prune_dumps
    local info
    info="$(run_timeout "$HEALTH_TIMEOUT" docker info \
      --format '{{.ServerVersion}} ({{.ContainersRunning}} running)' 2>/dev/null || true)"
    log "docker-nuke: Docker is back after ${elapsed}s — ${info:-ok}"
    log "docker-nuke: diagnostics in $DUMP_DIR"
    return 0
  fi

  verdict="daemon did not return within ${RESTART_TIMEOUT}s"
  elapsed=$(( $(date +%s) - started ))
  write_summary "$verdict" "$elapsed"
  prune_dumps
  warn "docker-nuke: $verdict"
  warn "docker-nuke: still running: $(docker_pids | tr '\n' ' ')"
  warn "docker-nuke: diagnostics in $DUMP_DIR"
  warn "docker-nuke: try 'docker-nuke --deep', or check disk space in $DUMP_DIR/disk.txt"
  return 1
}

# Only run when executed, not when sourced by the test harness.
if [ "${BASH_SOURCE[0]}" = "${0}" ]; then
  main "$@"
fi