#!/usr/bin/env bash
# Who is PID 1, does SIGTERM reach the JVM, and how long does `docker stop` take?
# -> docs/output/pid1-and-signals.txt
set -uo pipefail
source "$(dirname "$0")/env.sh"
probe() {
  local tag="$1" name="sig-$$"
  docker rm -f "$name" > /dev/null 2>&1
  docker run -d --name "$name" "sbd/docker-images:$tag" > /dev/null
  for _ in $(seq 1 200); do docker logs "$name" 2>&1 | grep -q 'Started ImagesApplication' && break; sleep 0.1; done
  local pid1
  # NUL-separated argv; translate in the pipe (a shell variable cannot hold NUL bytes)
  pid1=$(docker exec "$name" cat /proc/1/cmdline 2>/dev/null | tr '\0' ' ')
  case "$pid1" in ""|*"exec failed"*) pid1="(image has no cat; ENTRYPOINT is exec form)" ;; esac
  local t0 t1; t0=$(date +%s%N); docker stop "$name" > /dev/null; t1=$(date +%s%N)
  local code; code=$(docker inspect -f '{{.State.ExitCode}}' "$name")
  local graceful; graceful=$(docker logs "$name" 2>&1 | grep -c 'Commencing graceful shutdown' || true)
  printf '%-22s PID 1: %-58s docker stop: %5d ms  exit code: %-4s graceful-shutdown log lines: %s\n' \
    "$tag" "${pid1:0:58}" "$(( (t1 - t0) / 1000000 ))" "$code" "$graceful"
  docker rm -f "$name" > /dev/null
}
{
  echo "# docker stop sends SIGTERM to PID 1, waits 10 s, then SIGKILL. Exit code 143 = the JVM handled"
  echo "# SIGTERM (128+15). 137 = it was killed (128+9)."
  echo
  for t in layered-jre shell-form shell-form-alpine shell-form-wrapper layered-distroless; do probe "$t"; done
  echo
  echo "# What /bin/sh is in each base image:"
  echo "eclipse-temurin:25-jre         -> $(docker run --rm --entrypoint readlink eclipse-temurin:25-jre -f /bin/sh)"
  echo "eclipse-temurin:25-jre-alpine  -> $(docker run --rm --entrypoint readlink eclipse-temurin:25-jre-alpine -f /bin/sh)"
} | tee "$OUT/pid1-and-signals.txt"