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App container rkt
- 3. With containers what does a "Linux Distro" mean?
- 6. The Bad $ python --version Python 2.7.6 $ python app-requiring-python3.py $ python --version Python 3.4.3 $ python app-requiring-python2.py package collisions
- 7. The Bad $ cat /etc/os-release | grep ^NAME= NAME=Fedora $ rpm -i package-from-suse.rpm file /foo from install of package-from-suse.rpm conflicts with file from package-from-fedora dependency namespacing
- 8. The Good $ gpg --list-only --import /etc/apt/trusted.gpg.d/* gpg: key 2B90D010: public key "Debian Archive Automatic Signing Key (8/jessie) <ftpmaster@debian.org>" imported gpg: Total number processed: 1 gpg: imported: 1 (RSA: 1) gpg: no ultimately trusted keys found users control trust
- 9. The Good $ rsync ftp.us.debian.org::debian /srv/mirrors/debian $ dpkg -i /srv/mirrors/debian/kernel-image- 3.16.0-4-amd64-di_3.16.7-ckt9-2_amd64.udeb trivial mirroring and hosting
- 10. Linux Packages 2.0 .deb and .rpm for containers
- 11. Container VS VM? ● Lightweight (100s vs 10s) ● Easy to deploy ● Less isolation?
- 12. What is container ? ● Packaging with your apps with deps ● Running in isolation (using namespace, cgroups)
- 13. Why I want to use it? ● Deploy faster ● Run faster, run everywhere ● Run in isolation
- 15. appc != rkt
- 16. Application Containers self-contained, portable (decoupled from operating system) isolated (memory, network, …)
- 17. appc principles Why are we doing this?
- 18. Open Independent GitHub organisation Contributions from Cloud Foundry, Mesosphere, Google, Red Hat (and many others!)
- 19. Simple but efficient Simple to understand and implement, but eye to optimisation (e.g. content-based caching)
- 20. Secure Cryptographic image addressing Image signing and encryption Container identity
- 21. Standards-based Well-known tools (tar, gzip, gpg, http), extensible with modern technologies (bittorrent, xz)
- 22. Composable Integrate with existing systems Non-prescriptive about build workflows OS/architecture agnostic
- 23. appc components
- 24. Image Format Application Container Image tarball of rootfs + manifest uniquely identified by ImageID (hash)
- 25. Image Discovery App name → artifact example.com/http-server coreos.com/etcd HTTPS + HTML
- 26. Executor （Runtime) grouped applications runtime environment isolators networking
- 27. Metadata Service http://$AC_METADATA_URL/acMetadata container metadata container identity (HMAC verification)
- 28. ACE validator is this executor compliant with the spec? $EXECUTOR run ace_validator.aci
- 29. appc community
- 30. github.com/ cdaylward/libappc C++ library for working with app containers
- 31. github.com/ cdaylward/nosecone C++ executor for running app containers
- 33. github.com/ 3ofcoins/jetpack FreeBSD Jails/ZFS-based executor (by @mpasternacki)
- 34. github.com/ sgotti/acido ACI toolkit (build ACIs from ACIs)
- 37. appc spec in a nutshell - Image Format (ACI) - what does an application consist of? - Image Discovery - how can an image be located? - Pods - how can applications be grouped and run? - Executor (runtime) - what does the execution environment look like?
- 38. appc status Stabilising towards first backwards compatible release
- 40. rkt an implementation of appc
- 42. rkt a modern, secure container runtime
- 44. simple CLI tool golang + Linux self-contained init system/distro agnostic
- 45. simple CLI tool no daemon no API* apps run directly under spawning process
- 49. rkt internals modular architecture execution divided into stages stage0 → stage1 → stage2
- 50. rkt (stage0) pod (stage1) bash/runit/systemd/... (invoking process) app1 (stage2) app2 (stage2)
- 51. rkt (stage0) pod (stage1) bash/runit/systemd/... (invoking process) app1 (stage2) app2 (stage2)
- 52. stage0 (rkt binary) discover, fetch, manage application images set up pod filesystems commands to manage pod lifecycle
- 53. stage0 (rkt binary) - rkt run - rkt prepare - rkt run-prepared - rkt list - rkt status - ... - rkt fetch - rkt trust - rkt image list - rkt image export - rkt image gc - ...
- 54. stage0 (rkt binary) file-based locking for concurrent operation (e.g. rkt gc, rkt list for pods) database + reference counting for images
- 55. rkt (stage0) pod (stage1) bash/runit/systemd/... (invoking process) app1 (stage2) app2 (stage2)
- 56. rkt (stage0) pod (stage1) bash/runit/systemd/... (invoking process) app1 (stage2) app2 (stage2)
- 57. stage1 execution environment for pods app process lifecycle management isolators
- 58. stage1 (swappable) binary ABI with stage0 stage0 calls an execve(stage1)
- 59. stage1 (swappable) ● default implementation ○ based on systemd-nspawn+systemd ○ Linux namespaces + cgroups for isolation ● kvm implementation ○ based on lkvm+systemd ○ hardware virtualisation for isolation ● others?
- 60. rkt (stage0) pod (stage1) bash/runit/systemd/... (invoking process) app1 (stage2) app2 (stage2)
- 61. rkt (stage0) pod (stage1) bash/runit/systemd/... (invoking process) app1 (stage2) app2 (stage2)
- 62. stage2 actual app execution independent filesystems (chroot) shared namespaces, volumes, IPC, ...
- 63. rkt + systemd The different ways rkt integrates with systemd
- 64. rkt
- 66. systemd (on host) optional "systemctl stop" just works socket activation pod-level isolators: CPUShares, MemoryLimit
- 68. systemd-nspawn default stage1, besides lkvm taking care of most of the low-level things
- 72. application app-level isolators: CPUShares, MemoryLimit chrooted
- 74. systemd-journald no changes in apps required logs in the container available from the host with journalctl -m / -M
- 76. systemd-machined register on distros using systemd machinectl {show,status,poweroff…}
- 78. cgroups
- 79. What’s a control group? (cgroup) ● group processes together ● organised in trees ● applying limits to them as a group
- 80. cgroups
- 82. List of cgroup controllers /sys/fs/cgroup/ ├─ cpu ├─ devices ├─ freezer ├─ memory ├─ ... └─ systemd
- 83. /sys/fs/cgroup/ ├─ systemd │ ├─ user.slice │ ├─ system.slice │ │ ├─ NetworkManager.service │ │ │ └─ cgroups.procs │ │ ... │ └─ machine.slice How systemd units use cgroups
- 84. │... ├─ cpu │ ├─ user.slice │ ├─ system.slice │ └─ machine.slice │ └─ machine-rkt….scope │ └─ system.slice │ └─ app.service ├─ memory │ ├─ user.slice │ ├─ system.slice │ └─ machine.slice ... /sys/fs/cgroup/ ├─ systemd │ ├─ user.slice │ ├─ system.slice │ └─ machine.slice │ └─ machine-rkt….scope │ └─ system.slice │ └─ app.service │ │ │... How systemd units use cgroups w/ containers
- 85. /sys/fs/cgroup/ ├─ systemd │ ├─ user.slice │ ├─ system.slice │ └─ machine.slice │ └─ machine-rkt….scope │ └─ system.slice │ └─ app.service │ │ │... │... ├─ cpu │ ├─ user.slice │ ├─ system.slice │ └─ machine.slice │ └─ machine-rkt….scope │ └─ system.slice │ └─ app.service ├─ memory │ ├─ user.slice │ ├─ system.slice │ └─ machine.slice ... cgroups mounted in the container RW RO
- 86. Example: memory isolator “limit”: “500M” Application Image Manifest [Service] ExecStart= MemoryLimit=500M systemd service file write to memory.limit_in_ bytes systemd action
- 87. Example: CPU isolator “limit”: “500m” Application Image Manifest write to cpu.share systemd action [Service] ExecStart= CPUShares=512 systemd service file
- 88. Unified cgroup hierarchy ● Multiple hierarchies: ○ one cgroup mount point for each controller (memory, cpu, etc.) ○ flexible but complex ○ cannot remount with a different set of controllers ○ difficult to give to containers in a safe way ● Unified hierarchy: ○ cgroup filesystem mounted only one time ○ still in development in Linux: mount with option “__DEVEL__sane_behavior” ○ initial implementation in systemd-v226 (September 2015) ○ no support in rkt yet
- 89. rkt: a few other things - rkt and security - rkt API service (new!) - rkt networking - rkt and user namespaces - rkt and production
- 90. rkt and security "secure by default"
- 91. rkt security - image signature verification - privilege separation - e.g. fetch images as non-root user - SELinux integration - kernel keyring integration (soon) - lkvm stage1 for true hardware isolation
- 92. rkt API service (new!) optional, gRPC-based API daemon exposes information on pods and images runs as unprivileged user easier integration with other projects
- 93. rkt networking plugin-based Container Networking Interface (CNI)
- 94. Container Runtime (e.g. rkt) veth macvlan ipvlan OVS Container Networking Interface (CNI)
- 95. Networking, the rkt way
- 96. Network tooling ● Linux can create pairs of virtual net interfaces ● Can be linked in a bridge container1 container2 eth0 veth1 eth0 veth2 IP masquerading via iptables eth0 bridge
- 97. rkt and user namespaces
- 98. History of Linux namespaces ✓ 1991: Linux ✓ 2002: namespaces in Linux 2.4.19 ✓ 2008: LXC ✓ 2011: systemd-nspawn ✓ 2013: user namespaces in Linux 3.8 ✓ 2013: Docker ✓ 2014: rkt … development still active
- 99. Why user namespaces? ● Better isolation ● Run applications which would need more capabilities ● Per user limits ● Future? ○ Unprivileged containers: possibility to have container without root
- 100. 0 host 65535 4,294,967,295 (32-bit range) 0 container 1 655350 container 2 User ID ranges
- 101. unmapped User ID mapping /proc/$PID/uid_map: “0 1048576 65536” host container 1048576 65536 65536 unmappedunmapped
- 102. Problems with container images Container filesystem Container filesystem Overlayfs “upper” directory Overlayfs “upper” directory Application Container Image (ACI) Application Container Image (ACI) container 1 container 2 downloading web server
- 103. Problems with container images ● Files UID / GID ● rkt currently only supports user namespaces without overlayfs ○ Performance loss: no COW from overlayfs ○ “chown -R” for every file in each container
- 104. Problems with volumes / /home/var user / /data /my-app bind mount (rw / ro) /data ● mounted in several containers ● No UID translation /data
- 105. User namespace and filesystem problem ● Possible solution: add options to mount() to apply a UID mapping ● rkt would use it when mounting: ○ the overlay rootfs ○ volumes ● Idea suggested on kernel mailing lists
- 106. rkt and production - still pre-1.0 - unstable (but stabilising) CLI and API - explicitly not recommended for production - although some early adopters
- 107. rkt v1.0.0 EOY (fingers crossed) stable API stable CLI ready to use!
- 108. Questions? github.com/coreos/rkt coreos.com/careers (soon in Berlin!) Join us!