The fastest way to bootstrap Ruby on Rails

@ RubyKaigi 2019 ✨💎✨

Japanese Script: https://gist.github.com/udzura/9d21c4eaecf1c118268ea48c7974b62a

Transcript

1. The fastest way to bootstrap Ruby on Rails Presentation by Uchio Kondo @
2. Engineer @ GMO Pepabo, Inc. Uchio Kondo / @udzura https://blog.udzura.jp/ * Local Organizer of * Chair of CloudNative Days Fukuoka 2019 * Author of Japanese Ruby Books * Founder of Haconiwa (mruby on container) * 10 y.o. Rubyist * Container Enthusiast * System Programming Novice
3. Living and working in Fukuoka 3 ☕ We’re here! GMO Pepabo Office Yakuin, Fukuoka’s Best ☕ Town
4. Fukuoka.rb • @nagachika, @jimlock, @udzura(me) and many helpers/organizers from Fukuoka.rb !! We welcome Rubyists!! 4
5. A Creator of Haconiwa 5
6. A Japanese Script 6 • Or please check @udzura ’s newest tweet #rubykaigia .
7. Introduction to CRIU
8. CRIU (pronounced like screw’s crew) 8 https://criu.org/
9. I’ve sent a patch to CRIU • And I have read many parts of CRIU’s code (almost all in C language) 9
10. Have you heard • About “CRIU” ? 10
11. Have you heard • About “Process” ? 11
12. Processes (for Linux) • Processes are very basic concept on which OS executes tasks/programs. 12
13. CRIU • Using CRIU, We can: • Dump processes information info “image” files • Restore processes from dumped image files • CRIU stands for “Checkpoint and Restore In Userspace” • CRIU is a tool for processes, but it can be applied to containers C/R. 13
14. CRIU Internal: • CRIU uses /proc filesystems, cgroup attributes and stats, TCP checkpoint feature after Kernel 3.5, and many syscalls to get process info 14
15. Where CRIU is useful • 1) Migration • 2) Making apps fast in bootstrap 15
16. Migration example • cf. KVM’s live migration 16 Dump! Copy Restore! Reboot Host A Container Image Same Container Another Host
17. Faster bootstrap example • When you have a heavier app in bootstrap, like Jenkins, Redmine, or legacy monolithic Rails app, you will hesitate to reboot these. • e.g. Jenkins requires about 5 sec to boot
 (using docker with downloaded image). 17
18. Ahead-of-time process dump • CRIU can skip initialization process. • e.g. read() scripts and code evaluation. • Using CRIU program will be loaded directory from “memory dump” 18
19. Ahead-of-time process dump 19 Boot from scratch Boot using predump Memory Eval Direct Load Initialized
20. Example of CRIU utilization in Ruby on Rails
21. Detailed CRIU examples • Apply CRIU to Ruby on Rails applications!! 21
22. Environments • We have a application platform using containers: 22 Application Containers Proxy Routing by vhost Requests Deployment by users
23. Automated host migration • When one host is crashed, the new container is invoked automatically in another host. But this requires RESTART of a container... 23 Crash! Proxy Requests Restart and Redirect Accesses
24. Can we reduce restart time? • CRIU looked like a very good choice for this system. 24
25. Preliminary experiment • Created instances on vagrant as below: • Checking response time, this includes restart time 25
26. How to measure boot time 26 ngx_mruby Haconiwa Containers On the next request, restart an application container and forward access to this container in one transaction Force to stop by operation Haconiwa
27. The response time is composed of 27 Normal Container Response First Time Response with Boot Middleware work Middleware work App response App response Container bootstrap process
28. Result 28 Boot from scratch CRIU
29. Experiment on staging • Deployed simple Welcome Rails application to staging • Ran apache bench and plot response times • Invoke relocation between hosts, then check reboot time. 29
30. Experiments on staging 30 Relocate while the bench is running Proxy Then boot and serve
31. Result #1 • Without any technologies to fasten bootstrap(no bootsnap/no CRIU) 31
32. Result #2 • Activated bootsnap, but no CRIU utilization 32
33. Result #3 • Images were copied to all hosts, and utilized CRIU on bootstrap 33
34. Result of all 34
35. FYI: Scale out using CRIU • We can restore and spawn as many containers as you like from one CRIU's container image • This means CRIU can reduce costs of containers scale-out 35 Proxy Host
36. A tool to deploy applications fast - Grenadine
37. OK, CRIU is so effective for “container” bootstrapping. 37
38. But I guess you are thinking: • “Our application is deployed to VMs, NOT containers” 38
39. Migration VM->container is hard • Many aspects of system characteristics are varying between VMs and containers • VMs has an init process • daemons such as sshd and rsyslogd • a full-stack filesystem to manage whole operation system • ... all of which containers are usually omitting 39
40. Is there a tool to introduce checkpoint/restorte for “normal”, historical VMs? 40
41. Yes, there is. • I named the tool “Grenadine”, which is written in mruby for 41
42. Let me show you a DEMO. 42
43. The internal of Grenadine Advanced Topic!!
44. Warning: • Following talk is about Linux container runtimes implementation • Requires some of Linux kernel's container feature • But I’ll show you (m)ruby codes, which I guess you can read :) 44
45. What grenadine daemon do indeed • grenadine daemon creates a minimalistic container internally. 45 Grenadine daemon Application Minimalistic container described below App App wait() We’re here!
46. How to write a container in Ruby pid = Process.fork do
 isolate_namespace_using_unshare(flag) assign_to_cgroup(name) if enabled chroot_or_pivot_root(to: rootfs) # Doing other options exec(“/path/to/command”, “--opt1”, “--opt2”) end status = Process.waitpid2(pid) # will block and wait() puts status • NOTE: program should be single-threaded, so mruby is better 46
47. Grenadine unshare-s only PID Namespace and Mount Namespace • To avoid PID conflict: 47 12345 12347 12351 12345 12347 12351 12345 is Already taken! <- -> 1 6 4 1 6 4 No existing PID Root namespace Using isolated namespace Restore
48. 48 clone(CLONE_NEWNS| CLONE_NEWPID) wait() from Parent Re-mount /proc in new root
49. “Working with Unix Processes” 49 ʮͳΔ΄ͲUnixϓϩηεʯ
50. Grenadine requires no additional root filesystem • Grenadine creates ad-hoc root filesystem using bind-mount 50 / /run/gren/aaaa-bbbb /tmp /run/gren/aaaa-bbbb/tmp /var/log /run/gren/aaaa-bbbb/var/log /... /run/gren/aaaa-bbbb/... Bind-mount pivot_root !!
51. 51 Generates new root For bind-mount dest Bind-mount “/“ and any important directories Mount namespace is isolated, so it is invisible from host
52. To make checkpoint easily • The processes Grenadine creates look like a normal, VM-based application daemon • Internally some of attributes are unshared • To allow CRIU to create checkpoints easily • Grenadine is aimed that it can be introduced into historical VM-based application environments with least changes 52
53. Toward “Cloud Native”...
54. Tha age of Cloud Native • Now is the time everything becomes containerized, orchestrated and microservice-based... 54
55. Grenadine in the future • Grenadine can be used for historical VMs now • I want people to use Grenadine as a checkpoint/restore tool for Kubernetes or other container-based systems • It is cloud-native middleware!! (Like ones on CNCF incubators) 55
56. Please try Grenadine • Current Grenadine have great chemistry with smaller applications • But soon it can be applied with larger apps :) • I will release rpm or deb file - as soon as possible. :( 56
57. Enjoy using next generation kernel features! 57
58. Thanks!!
59. References • Papers: • দຊ྄հ, ۙ౻Ӊஐ࿕, CRIUΛར༻ͨ͠HTTPϦΫΤετ୯ҐͰίϯςφ Λ࠶഑ஔͰ͖Δ௿ίετͰߴ଎ͳεέδϡʔϦϯάख๏, ৘ใॲཧֶձ ݚڀใࠂΠϯλʔωοτͱӡ༻ٕज़ʢIOTʣ, No.2019-IOT-44, Vol.21, pp.1-8, 2018೥3݄. 59
60. References • Websites: • CRIU.org https://criu.org/Main_Page • Introduction to CRIU https://speakerdeck.com/udzura/introduction-to- criu • Grenadine on GitHub: https://github.com/udzura/grenadine • Japanese article: https://udzura.hatenablog.jp/entry/ 2019/03/07/202615 60