DockerCon 2016 - Windows Server and Docker
- 1. Windows Server and Docker The Internals Behind Bringing Docker and Containers to Windows John Starks & Taylor Brown Principal Leads in Windows
- 2. Basics Architecture Porting Docker Agenda Shallow dive Namespaces File system Base images Hyper-V Containers Two great things Better together
- 4. Docker on Windows • Not “Docker for Windows” • Integration coming • Port of Docker Engine (not a fork) • Same remote API, same tools work on top (Compose, Swarm, etc.) • Built on new native container technology in Windows • Runs on Windows Server 2016 and on the latest Windows 10 • Runs Windows Server containers on Windows hosts • Doesn't run Linux containers • Available to try now • http://aka.ms/containers
- 5. Demo!
- 6. How? • New system-level container capabilities in Windows • Namespaces • Resource controls • Union file system • Adapted Docker to Windows • Adapted Windows to Docker
- 7. Architecture In Linux containerd + runc REST Interface libcontainerd graphlibnetwork plugins Control Groups cgroups Namespaces Pid, net, ipc, mnt, uts Layer Capabilities Union Filesystems AUFS, btrfs, vfs, zfs*, DeviceMapper Other OS Functionality Docker Client Docker Registry Docker Compose Docker Swarm
- 8. Architecture In Windows REST Interface libcontainerd graphlibnetwork plugins Control Groups Job objects Namespaces Object Namespace, Process Table, Networking Layer Capabilities Registry, Union like filesystem extensions Other OS Functionality Compute Service Docker Client Docker Registry Docker Compose Docker Swarm
- 9. Compute Service • Public interface to containers • Replaces containerd on Windows • Manages running containers • Abstracts low-level capabilities • Language bindings available • C#: https://github.com/Microsoft/ dotnet-computevirtualization • Go: https://github.com/Microsoft/ hcsshim
- 11. Host User Mode Container Management Windows Server Containers System Processes Application Processes System Processes System Processes Application Processes
- 12. Container contents • Public Windows API delivered via DLLs, not syscalls • Lots of interdependencies • Highly dependent on system services running • RPC calls hidden in Win32 APIs • Automatically starts smss • init equivalent • Launches a variety of system services • No “FROM scratch”
- 13. Base images • Distributed by Microsoft • Two options • windowsservercore: large (huge?), highly compatible • nanoserver: small, fast, smaller API surface • docker pull coming soon! • microsoft/windowsservercore • microsoft/nanoserver
- 14. Demo!
- 15. Namespaces • Silo: extension to Windows Job object • Set of processes • Resource controls • New: set of namespaces • New namespace virtualization • Registry • Process IDs, sessions • Object namespace • File system • Network compartments
- 16. Object namespace • System-level namespace, hidden from users • C:Windows maps to DosDevicesC:Windows • Contains all device entry points • DosDevicesC: • Registry • DeviceTcp • Silo can "chroot" to different object root • SilosfooDosDevicesC: • SilosbarDosDevicesC:
- 17. Demo!
- 18. File system • Windows applications expect NTFS semantics • Transactions, file IDs, USN journal • Building a full union FS with NTFS semantics is hard • Hybrid model • Virtual block device + NTFS partition per container • Symlinks to layers on host FS to keep block devices small
- 19. Registry… Windows Registry • Basically a simple file system • Built a true union FS • Saves cloning a full set of registry hives per container
- 21. Hyper-V Containers • Some workloads need more isolation • Hostile multi-tenancy • Regulated workloads • Solution: transparently run each container in a VM! • (Mostly) invisible to both Docker and the user • docker run --isolation=hyperv • Hyper-V Containers are the default on Windows 10 • Images are the same
- 22. Host User Mode Container Management Windows Server Containers System Processes Application Processes System Processes System Processes Application Processes
- 23. Hyper-V Containers Host User Mode Virtual Machine Specifically Optimized To Run a Container Container Management System Processes System Processes Application Processes
- 24. Making it work • Small, stateless “utility VM” • Smallest Windows yet? • Writes not persisted • Storage attached via SMB • VMBus transport • File cache sharing • Networking attached via virtual NIC
- 25. Cloning • Launching the utility VM takes time and memory • Do it once, freeze the result • Fork the VM for each new instance • Eliminates startup time • Shares memory
- 26. Demo!
- 27. Thank you!
Editor's Notes
- #6: * docker images * docker run --rm test cmd /c echo Hello DockerCon!
- #15: * docker run -it --rm windowsservercore powershell get-process * docker run -it --rm nanoserver powershell get-process * Look at taskmgr
- #18: * objdir \ * objdir \DosDevices * docker run -it --rm test cmd objdir \DosDevices
- #27: * docker run --rm --isolation=hyperv test cmd /c echo Help, I'm trapped in a VM! * Run it again (should be faster) * docker run --rm -it --isolation=hyperv test cmd powershell get-process * Show taskmgr on host