Hardening Image for Gluu/Janssen

Ideas

1 - Prevent reverse shell by removing access to sh

As we are using alpine-based image which uses busybox applets (for example sh is a shortcut to busybox sh command, there are several ways to remove shell

1.1 - Use custom busybox

Pros

1. Only include required busybox applets or simply remove unwanted applet, i.e. sh

Cons

1. Need to compile a customized busybox within custom alpine image

1.2 - Uninstall busybox before ENTRYPOINT/CMD directive

Pros

1. No need to build/use custom alpine image

Cons

1. Since busybox is uninstalled, all applets will not be available, this includes tools for troubleshoot (i.e. cat, ls, netstat, etc.)

Things to consider:

1. Some image entrypoints are shell script that sometime spawn multiple Python / Java / shell commands; this requires refactoring for example using supervisor (Python-based tool) to manage processes
2. ...