Scripts: Add dist/add-swap.sh to help configure swap on Linux

see https://docs.photoprism.app/getting-started/troubleshooting/docker

Signed-off-by: Michael Mayer <michael@photoprism.app>

scripts/dist/add-swap.sh

@@ -0,0 +1,33 @@
+#!/usr/bin/env bash
+
+# Adds a persistent swap file with a default size of 16G if swap space has not yet been configured.
+# bash <(curl -s https://raw.githubusercontent.com/photoprism/photoprism/develop/scripts/dist/add-swap.sh)
+
+# Show usage information if first argument is --help, and if not executed as root.
+if [[ $(id -u) != "0" ]] || [[ ${1} == "--help" ]]; then
+  echo "Adds a persistent swap file with a default size of 16G if swap space has not yet been configured."
+  echo "Usage: run \"${0##*/} [size]\" as root" 1>&2
+  exit 0
+fi
+
+# Check if swap is already configured.
+if [[ $(swapon --show) ]]; then
+    echo "Swap space has already been configured:"
+    swapon --show
+    exit 0
+fi
+
+set -e
+
+# Add swap as requested, 16G by default.
+SWAP_SIZE=${2:-16G}
+
+fallocate -l "${SWAP_SIZE}" /swapfile
+chmod 600 /swapfile
+mkswap /swapfile
+swapon /swapfile
+echo '/swapfile none swap sw 0 0' | tee -a /etc/fstab
+
+# Check if swap was added successfully.
+echo "A persistent /swapfile with a size of ${SWAP_SIZE} was added:"
+swapon --show