Add gosu and host user to Docker

docker/entrypoint.sh

@@ -0,0 +1,33 @@
+#!/usr/bin/env bash
+
+set -eo pipefail; [[ "$TRACE" ]] && set -x
+
+if [[ "$(id -u)" -ne 0 ]]; then
+    echo 'docker-entrypoint requires root' >&2
+    exit 1
+fi
+
+if [ -z "$UID" ] || [ "$UID" = "0" ]; then
+  echo "UID must be specified as a positive integer"
+  exit 1
+fi
+
+if [ -z "$GID" ] || [ "$GID" = "0" ]; then
+  echo "GID must be specified as positive integer"
+  exit 1
+fi
+
+USER=$(id -un $UID 2>/dev/null || echo "hostuser")
+GROUP=$(getent group $GID | cut -d: -f1 || echo "hostgroup")
+
+if [ "$USER" = "hostuser" ]; then
+  useradd -u $UID -s /bin/bash -m $USER
+fi
+
+if [ "$GROUP" = "hostgroup" ]; then
+  groupadd -g $GID $GROUP
+fi
+
+usermod -g $GROUP $USER
+
+exec "$@"