preserve ssh host keys across updates

fixes #2

Dockerfile

@@ -2,6 +2,7 @@ FROM cloudron/base:0.8.0
 
 RUN apt-get update && \
     apt-get install -y openssh-server && \
+    rm -rf /etc/ssh_host_* && \
     rm -r /var/cache/apt /var/lib/apt/lists
 
 ADD supervisor/ /etc/supervisor/conf.d/

start.sh

@@ -29,8 +29,24 @@ if [[ -z "${SSH_PORT:-}" ]]; then
     disable_ssh="true"
 fi
 
+if [[ ! -f "/app/data/sshd/ssh_host_ed25519_key" ]]; then
+    echo "Generating ssh host keys"
+    mkdir -p /app/data/sshd
+    ssh-keygen -qt rsa1 -N '' -f /app/data/sshd/ssh_host_key
+    ssh-keygen -qt rsa -N '' -f /app/data/sshd/ssh_host_rsa_key
+    ssh-keygen -qt dsa -N '' -f /app/data/sshd/ssh_host_dsa_key
+    ssh-keygen -qt ecdsa -N '' -f /app/data/sshd/ssh_host_ecdsa_key
+    ssh-keygen -qt ed25519 -N '' -f /app/data/sshd/ssh_host_ed25519_key
+else
+    echo "Reusing existing host keys"
+fi
+
+chmod 0600 /app/data/sshd/*_key
+chmod 0644 /app/data/sshd/*.pub
+
 sed -e "s/^Port .*/Port ${SSH_PORT}/" \
     -e "s/^#ListenAddress .*/ListenAddress 0.0.0.0/" \
+    -e "s,^HostKey /etc/ssh/,HostKey /app/data/sshd/," \
     /etc/ssh/sshd_config > /run/gogs/sshd_config
 
 sed -e "s/##DOMAIN/${APP_DOMAIN}/g" \