Add PD to Serenity backup automation scaffolding

automation/bin/pd_backup_lib.sh

@@ -0,0 +1,73 @@
+#!/usr/bin/bash
+set -euo pipefail
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+AUTOMATION_DIR="$(cd "$SCRIPT_DIR/.." && pwd)"
+ENV_FILE="${ENV_FILE:-$AUTOMATION_DIR/.env}"
+
+if [[ ! -f "$ENV_FILE" ]]; then
+  echo "Missing env file: $ENV_FILE" >&2
+  echo "Copy automation/.env.example to automation/.env and fill in real values first." >&2
+  exit 1
+fi
+
+set -a
+# shellcheck disable=SC1090
+source "$ENV_FILE"
+set +a
+
+required_vars=(
+  SERENITY_BACKUP_HOST
+  SERENITY_BACKUP_ROOT
+  PD_APPDATA_ROOT
+  PD_DATABASES_ROOT
+  PD_TANK_DOCKER_ROOT
+  PD_DB_DUMP_ROOT
+  POSTGRES_CONTAINER
+)
+
+for var in "${required_vars[@]}"; do
+  if [[ -z "${!var:-}" ]]; then
+    echo "Required variable $var is empty in $ENV_FILE" >&2
+    exit 1
+  fi
+done
+
+mkdir -p "$PD_DB_DUMP_ROOT"
+
+DOCKER_BIN="${DOCKER_BIN:-/usr/bin/docker}"
+SUDO_BIN="${SUDO_BIN:-/usr/bin/sudo}"
+USE_SUDO_FOR_DOCKER="${USE_SUDO_FOR_DOCKER:-true}"
+BACKUP_KNOWN_HOSTS="${BACKUP_KNOWN_HOSTS:-${HOME:-/root}/.ssh/known_hosts}"
+
+if [[ ! -x "$DOCKER_BIN" ]]; then
+  echo "Docker binary not executable: $DOCKER_BIN" >&2
+  exit 1
+fi
+
+docker_cmd() {
+  if [[ "${EUID:-$(id -u)}" == "0" ]]; then
+    "$DOCKER_BIN" "$@"
+  elif [[ "$USE_SUDO_FOR_DOCKER" == "true" ]]; then
+    "$SUDO_BIN" -n "$DOCKER_BIN" "$@"
+  else
+    "$DOCKER_BIN" "$@"
+  fi
+}
+
+timestamp_utc() {
+  date -u +"%Y%m%dT%H%M%SZ"
+}
+
+ssh_args() {
+  local opts="-o BatchMode=yes -o StrictHostKeyChecking=accept-new -o UserKnownHostsFile=$BACKUP_KNOWN_HOSTS"
+  if [[ -n "${BACKUP_SSH_KEY:-}" ]]; then
+    printf '%s' "-i $BACKUP_SSH_KEY $opts"
+  else
+    printf '%s' "$opts"
+  fi
+}
+
+ssh_cmd() {
+  printf 'ssh %s' "$(ssh_args)"
+}