Added tutorial about container to README

Docker/Dockerfile/entrypoint.sh

@@ -0,0 +1,30 @@
+#!/bin/sh
+set -e
+
+# Default to 1600 if not provided
+PUID="${PUID:-1600}"
+PGID="${PGID:-1600}"
+USER="${USER:-apiusr}"
+GROUP="${USER:-apiusr}"
+CHOWNPATH="/netflowParser"
+
+# Create group if missing
+if ! getent group "$GROUP" >/dev/null 2>&1; then
+    addgroup -g "$PGID" "$GROUP"
+fi
+
+# Create user if missing
+if ! id -u "$USER" >/dev/null 2>&1; then
+    adduser -D -u "$PUID" -G "$GROUP" "$USER"
+fi
+
+# Download IP2Location database
+if [[ -n "$IP2LOC_TOKEN" ]]; then
+    wget -O "$CHOWNPATH"/IP2LOCATION-LITE-DB9.BIN "https://www.ip2location.com/download/?token="$IP2LOC_TOKEN"&file=DB9LITEBIN"
+fi
+
+# Fix permissions (only do this on /app/API)
+chown -R "$PUID:$PGID" "$CHOWNPATH"
+
+# Drop privileges & run command
+exec su-exec "$PUID:$PGID" "$@"