make adding startup tasks more easily extensible

Dockerfile

@@ -24,7 +24,8 @@ COPY sshd.conf /etc/supervisor/conf.d/sshd.conf
 COPY cron.conf /etc/supervisor/conf.d/cron.conf
 
 COPY start /start
-RUN chmod +x /start
+RUN chmod +x /start ; mkdir /start.d
+COPY regenerate-ssh /start.d/regenerate-ssh
 
 # Expose ssh
 EXPOSE 22

regenerate-ssh

@@ -0,0 +1,10 @@
+#! /bin/bash
+
+# If sshd has no config, generate new keys + config
+if [ ! -f /etc/ssh/sshd_config ]; then
+    # Regenerate ssh key per container
+    dpkg-reconfigure openssh-server
+fi
+
+# This only runs once, so remove this startup script
+rm /start.d/regenerate-ssh

start

@@ -1,9 +1,7 @@
 #!/bin/bash
 
-if [ ! -f /etc/ssh/sshd_config ]; then
-    # Regenerate ssh key per container
-    dpkg-reconfigure openssh-server
-fi
+# run everything in start.d
+find /start.d -type f -executable -exec {} \;
 
 # Cleanly kill supervisor when container is stopped
 trap 'kill $(jobs -p)' EXIT