Add ability to save logs to file

use env `LOG=TRUE`

docker-entrypoint.sh

@@ -2,6 +2,17 @@
 set -e
 #set -x
 
+if [ "${LOG}" == "TRUE" ]; then
+    LOG_DIR=/var/log/letsencrypt
+	LOG_FILE=${LOG_DIR}/runtime.log
+	mkdir -p ${LOG_DIR}
+	touch ${LOG_FILE}
+
+	UUID=$(cat /proc/sys/kernel/random/uuid)
+	exec > >(read message; echo "$(date -Iseconds) ${UUID} [info] $message" | tee -a ${LOG_FILE} )
+	exec 2> >(read message; echo "$(date -Iseconds) ${UUID} [error] $message" | tee -a ${LOG_FILE} >&2)
+fi
+
 if [ "${LE_ENV}" == 'production' ]; then
 	echo "***** ${LE_ENV} *****"
 	sed -i 's@CA=.*@CA="https://acme-v01.api.letsencrypt.org/directory"@g' /etc/dehydrated/config