OpenStack is very good at launching virtual machines – that’s its purpose, isn’t it? But usually you want to monitor state of you machines somehow, and there are many reasonable ways.
- You can test daemons running on the machine, e.g., check up open ports or poll known services. Of course, this approach means that you know exactly what services should be running – and this is the most precise way to test system health.
- You can ask hypervisor if the machine is ok. That’s a very dirty check since hypervisor will likely report that VM is active while its operating system kernel can encounter problems.
- A compromise settlement may be pinging the machine. It’s a general solution since a lot of VMs respond to ping normally. Sure, VM can ignore ping or its daemons can have problems while host is responding to ping, but this solution is far easier to…
View original post 728 more words