#!/bin/sh
# Zero-downtime rolling deploy for the pawfeed-1/2/3 replicas.
#
# Builds the shared image once, then restarts each replica one at a time,
# waiting for the Docker healthcheck (GET /api/health, see
# docker-compose.yml) to report "healthy" before moving to the next one.
# At every point at least 2 of 3 replicas are serving traffic, so NPM's
# least_conn upstream (docker/npm-upstream.conf) never has fewer than 2
# healthy backends. `docker compose up -d --build` (start.sh) still works
# for a first-time deploy or when downtime doesn't matter — use this
# script for routine deploys against a live site instead.
set -e
cd "$(dirname "$0")"

if [ ! -f .env ]; then
  echo "ERROR: docker/.env not found."
  echo "Copy .env.example to docker/.env and fill in your values."
  exit 1
fi

export SENTRY_RELEASE="$(git -C .. rev-parse --short HEAD)"

REPLICAS="pawfeed-1 pawfeed-2 pawfeed-3"
TIMEOUT_SECS=60

echo "Building shared image..."
docker compose build pawfeed-1

wait_healthy() {
  replica="$1"
  elapsed=0
  while [ "$elapsed" -lt "$TIMEOUT_SECS" ]; do
    status="$(docker inspect --format='{{.State.Health.Status}}' "$replica" 2>/dev/null || echo "starting")"
    if [ "$status" = "healthy" ]; then
      return 0
    fi
    sleep 2
    elapsed=$((elapsed + 2))
  done
  return 1
}

for replica in $REPLICAS; do
  echo "--- Redeploying $replica ---"
  docker compose up -d --no-deps "$replica"

  echo "Waiting for $replica to report healthy (up to ${TIMEOUT_SECS}s)..."
  if wait_healthy "$replica"; then
    echo "$replica is healthy."
  else
    echo "ERROR: $replica did not become healthy within ${TIMEOUT_SECS}s."
    echo "Check: docker logs $replica"
    echo "Aborting before touching the remaining replicas — the ones already"
    echo "redeployed keep running, the rest are untouched and still on the old image."
    exit 1
  fi
done

echo "Rolling deploy complete — all 3 replicas updated with zero downtime."