add sftp storage

entrypoint.sh

@@ -1,12 +1,17 @@
 #!/bin/sh
 
-set -eu
+set -eu -o pipefail
 
 apk add --upgrade --no-cache bash restic python3 py3-pip
 
 # Todo use requirements file with specific versions
 pip install click docker resticpy
 
+if [ -n "$SSH_HOST_KEY" ]
+then
+    echo "$SSH_HOST_KEY" > /root/.ssh/known_hosts
+fi
+
 cron_schedule="${CRON_SCHEDULE:?CRON_SCHEDULE not set}"
 
 echo "$cron_schedule backup create" | crontab -