Lesson 18: Application Isolation¶
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Application Isolation¶
Virtual Machines¶
[vm] # ps aux
USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND
root 1 0.0 0.6 110564 3164 ? Ss 2015 11:17 /lib/systemd/systemd --system --deserialize 15
root 2 0.0 0.0 0 0 ? S 2015 0:00 [kthreadd]
root 3 0.0 0.0 0 0 ? S 2015 3:55 [ksoftirqd/0]
root 5 0.0 0.0 0 0 ? S< 2015 0:00 [kworker/0:0H]
[... 120+ more lines ...]
[host] # ps aux
USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND
root 1 0.0 0.1 200328 5208 ? Ss Aug25 0:44 /sbin/init
root 2 0.0 0.0 0 0 ? S Aug25 0:00 [kthreadd]
root 3 0.0 0.0 0 0 ? S Aug25 0:05 [ksoftirqd/0]
root 5 0.0 0.0 0 0 ? S< Aug25 0:00 [kworker/0:0H]
[... 240+ more lines ...]
OS Emulation¶
Containers¶
$ ps aux # Lists all processes running on an OS
PID USER TIME COMMAND
1 root 0:00 sh
6 root 0:00 ps aux
Not a Virtual Machine¶
CGroups + Systemd¶
Pros¶
| Virtual Machines | Containers |
| Complete process isolation | Fast startup |
| ‘Battle Tested’ | Little overhead |
Cons¶
| Virtual Machines | Containers |
| Slightly more overhead. | Security concerns. |
| Slow startup. | No cross-kernel emulation. |
| Cross-OS emulation. |
Tools¶
| Virtual Machines | Containers |
| VirtualBox | Docker |
| VMWare | Rkt |
Virtual Machines¶
- VirtualBox
An Open Source VM Manager.
Widely used and supported on Linux, Mac, and Windows.
- VMWare
A closed source VM Manager.
VMWare is a widely used and tends to have better performance than Virtual Box. While it can emulate Linux it does not work natively on Linux.
- KVM
The Kernel-based Virtual Machine.
Linux’s native infrastructure for handling Virtual Machines and emulation. Usually used in a larger emulation program, not alone.
Containers¶
- Docker
The defacto CLI tool for creating and using containers.
Very popular and well integrated into other tools.
- RKT
- A competitor to Docker created by CoreOS. Approaches container management from a different angle which has it’s advantages and disadvantages.
- chroot
- The oldschool way to use containers. Not a container in the modern sense, but achieves similar isolation.
- Jails
- The BSD Unix form of containerization. Offers a level of secure isolation not really possible in Linux.