Build, Ship, and Run Any App, Anywhere

COEP FOSSMeet’18 is the first edition of College of Engineering, Pune’s own Free and Open Source Software event. This meet has a vision to promote the culture of openness,innovation, and freedom. The meet intends to bring togetherFOSS developers, academicians, researchers, students and all those who love the FOSS movement. The meet intends to participate in the FOSS development and adoption process through hands-on sessions, discussions and lectures.

Transcript

1. Build, Ship, and Run Any App, Anywhere COEP FOSSMeet'18 Rahulkrishnan R A
2. About Me » Consultant @ Capgemini » Debian Contributor » Gopher » Organizer of kubernetes Meetup, Chennai Docker 101 LinkedIn linkedin.com/in/rahulkrishnanra/ Github https://github.com/rahulkrishnanfs Twitter https://twitter.com/rahulkrishnanra
3. 3 What is namespace? » Feature of the Linux kernel that partitions kernel resources » Limits what you can see » Namespaces are the fundamental aspect of containers on Linux
4. 4 Types of namespace o pid (processes) o net (network stack) o mnt (mount points, filesystems) o uts (hostname) o ipc (System V IPC) o user (UIDs) o cgroups
5. 5 What are they ? root@ip-172-31-43-99:/# ls -la /proc/4015/ns/ total 0 lrwxrwxrwx 1 cgroup -> cgroup:[4026531835] lrwxrwxrwx 1 ipc -> ipc:[4026531839] lrwxrwxrwx 1 mnt -> mnt:[4026531840] lrwxrwxrwx 1 net -> net:[4026531993] lrwxrwxrwx 1 pid -> pid:[4026531836] lrwxrwxrwx 1 user -> user:[4026531837] lrwxrwxrwx 1 uts -> uts:[4026531838]
6. 6 PID namespace » Processes within a PID namespace only see processes in the same PID namespace » Each PID has its own numbering » Namespace will be killed if PID one goes away » Behavior like the “init” process » PID namespace can be nested, up to 32 nesting levels
7. 7 1 2 3 4, 1 5, 2 6, 3 Child PID namespace parent PID namespace
8. Network Namespace » Logical copy of the network stack It has its own:  routes  firewall rules  network devices  IP address » It helps to separate application/process networking » You can move network interface across netns » Newly created network namespace includes only the loopback device
9. Child net namespace Child net namespace Global net namespace Interface Interface routing Network Interface
10. Mount namespace » Processes can have their own rootfs » Mounts can be totally private or shared » In the new mount namespace, all previous mounts will be visible » Mounts/unmounts in the global namespace are visible in that namespace
11. UTS namespace » Appears to have different host and domain names to different processes. » UTS namespace provides a way to get information about the system with commands like uname or hostname » Simple one to implement
12. UTS namespace Implementation func main() { cmd := exec.Command("/bin/sh") cmd.SysProcAttr = &syscall.SysProcAttr{ Cloneflags: syscall.CLONE_NEWUTS, } syscall.Sethostname([]byte("inner")) if err := cmd.Run(); err != nil { panic(err) } }
13. IPC namespace » Private set of IPC objects inside namespace eg: shm
14. User namespace » Allows to map UID/GID » Avoid extra configuration in containers » Security improvement
15. Container runtime - Docker
16. How containers looks like? Containers Virtual Machines
17. Interest on Docker – Google trends https://trends.google.co.in/trends/explore?date=today%205-y&q=docker
18. Docker Engine Docker Engine is a client-server application with these major components: » A REST API which specifies interfaces that programs can use to talk to the daemon and instruct it what to do » A command line interface (CLI) client ( the docker command) » A server which is a type of long-running program called a daemon process (the dockerd command)
19. Docker architecture
20. How docker access the linux kernel?
21. Docker Images vs Containers Images » Lightweight, stand-alone, executable package » Includes everything needed to run a piece of software, including the code, a runtime, libraries, environment variables, and config files. Container » Runtime instance of an image—what the image becomes in memory when actually executed.
22. Docker Image
23. Sharing the docker image
24. “ Demo 24
25. “ Questions 25
26. “ Thanks !!! Follow me @rahulkrishnanra 26