Add lego install script

bin/install-lego-system

@@ -0,0 +1,65 @@
+#!/usr/bin/env bash
+
+set -e
+
+VERSION=${VERSION:-v4.1.0}
+
+PREFIX_DIR=/usr/local
+BIN_DIR=${PREFIX_DIR}/bin
+
+APP=lego
+
+APP_PREFIX_DIR=${PREFIX_DIR}/apps/${APP}
+APP_DEST_DIR=${APP_PREFIX_DIR}/${VERSION}
+APP_CURRENT=${APP_PREFIX_DIR}/current
+
+OS=
+if [[ $OSTYPE =~ linux ]]; then
+    OS=linux
+elif [[  $OSTYPE =~ darwin ]]; then
+    OS=darwin
+else
+    echo unknown os: "$OSTYPE"
+    exit 1
+fi
+
+ARCH=
+if [[ $(uname -m) == x86_64 ]]; then
+    ARCH=amd64
+else
+    echo arch not yet supported: "$(uname -m)"
+    exit 1
+fi
+
+URL=https://github.com/go-acme/lego/releases/download/${VERSION}/lego_${VERSION}_${OS}_${ARCH}.tar.gz
+
+[[ -d ${APP_DEST_DIR} ]] || sudo mkdir -p "${APP_DEST_DIR}"
+
+TMP_DIR=
+if [[ ! -f ${APP_DEST_DIR}/lego ]]; then
+    TMP_DIR=$(mktemp --directory)
+    DEST_FILE=$TMP_DIR/${APP}.tar.gz
+    echo downloading "${APP}" "${VERSION}" to temp directory "${TMP_DIR}"
+    curl --silent --location --output "${DEST_FILE}" "${URL}"
+
+    sudo tar xf "${DEST_FILE}" --directory "${APP_DEST_DIR}"
+    sudo chown --recursive root:root "${APP_DEST_DIR}"
+else
+    echo "${APP}" "${VERSION}" already installed
+fi
+
+cd ${APP_PREFIX_DIR}
+[[ -s current ]] && sudo unlink current
+sudo ln --symbolic "${APP_DEST_DIR}" current
+echo current version set to "${VERSION}"
+
+cd ${BIN_DIR}
+# shellcheck disable=SC2044
+for bin in $(find ${APP_CURRENT}/ -maxdepth 1 -executable -type f -exec basename {} \;); do
+    [[ -s $bin ]] || sudo ln --symbolic "${APP_CURRENT}/$bin"
+done
+
+if [[ $TMP_DIR != "" ]]; then
+    rm -rf "${TMP_DIR}"
+    echo removed up temp directory "${TMP_DIR}"
+fi