In this session, we'll go into details about the latest developments around some of the components behind the core features of the Docker Platform. We'll cover the containerd runtime that was built to serve as an underlying daemon for Docker and Kubernetes, and BuildKit, a toolkit that builds on containerd to provide next-generation capabilities for building software with the help of containers. You will learn about the architecture and design choices of these projects, for example, the power of containerd's rich client library and BuildKit's frontend model that allows introducing new build languages or Dockerfile features. You can discover how you can use these projects directly and how they are being integrated into the Docker Platform.

1. Michael Crosby
Engineer, Docker Inc.
Docker Platform Internals
containerd and BuildKit
Tonis Tiigi
Engineer, Docker Inc.

2. ● Container runtime for platform builders
● Scoped to a local node
● Stable GRPC API
● Native Kube support in 1.1 via CRI
containerd

3. containerd smart client

4. ● Responsibilities split between client and server
○ Image fetch vs image storage
○ i/o creation and redirection
○ Snapshot creation vs snapshot unpacking
What is a smart client?

5. Why build a smart client?

6. ● Single daemon and API regardless of consumer
● Innovation kept at platform level
● Runtime kept boring and stable
One daemon to rule them all...

7. What do you get?

8. ● Multi Tenancy
○ Containerd namespaces
What do you get?

9. Namespaces

10. ● Direct I/O access
What do you get?

11. I/O

12. ● Containers as types
What do you get?

13. Containers as types

14. ● youtube-dl (mp4) | ffmpeg > audio.mp3
● No I/O Copy
https://github.com/crosbymichael/pipelines-dockercon
Pipelines

15. Pipelines

16. https://github.com/containerd/containerd
Get Involved

17. buildkit

18. BuildKit
New open source
builder toolkit
Fast, safe, extensible

19. BuildKit
Replacing builder backend
in Docker daemon
Experimental opt-in
feature in v18.06

20. BuildKit
Used by
Moby / Docker CE - experimental support in v18.06
genuinetools/img (Jessie Frazelle)
OpenFaas Cloud (Alex Ellis)
containerbuilding/cbi (Akihiro Suda)

21. BuildKit Features
No side-effects
Quality, performance, extensibility
Parallel requests support
Concurrent solver
Easy storage management (GC)
Custom language support
Custom Dockerfile features
Incremental build context sending
Persistent cache checksums
Secure git cache roots
HTTP dependency caching
Multiple inputs/outputs
Nested invocations
Multi-format export
OpenTracing support
Signable image manifests
Automatic build context detection
Remote build cache
Skip unused stages
Per-host registry authentication

22. BuildKit
Performance example
Based on github.com/moby/moby Dockerfile, master branch. Smaller is better.

23. BuildKit
Performance example
Based on github.com/moby/moby Dockerfile, master branch. Smaller is better.
Time for full build from empty state
2.0x
faster
Measured on DO 4vcpu droplet

24. BuildKit
Performance example
Based on github.com/moby/moby Dockerfile, master branch. Smaller is better.
Repeated build with matching cache
7.2x
faster
Measured on DO 4vcpu droplet

25. BuildKit
Performance example
Based on github.com/moby/moby Dockerfile, master branch. Smaller is better.
Repeated build with new source code
2.5x
faster
Measured on DO 4vcpu droplet

26. BuildKit
Performance example
Based on github.com/moby/moby Dockerfile, master branch. Smaller is better.
Fresh build with --cache-from from remote source
9.1x
faster
Measured on DO 4vcpu droplet

27. BuildKit
Embedding or using directly
Usable as a library,
as a standalone daemon or with containerd

28. BuildKit
buildkitd & buildctl

29. BuildKit
buildkitd & buildctl
gRPC API
Go client library
rootless execution
OpenTracing
multi-worker model

30. BuildKit
buildkitd & buildctl
gRPC API
Go client library
rootless execution
OpenTracing
multi-worker model
llb.Image("alpine:latest").
AddEnv("FOO", "BAR").
Dir("/dir").
Run(llb.Shlex("ls -l"), llb.AddEnv("key", "val"))
r := Run(llb.Shlex("..."))
r.AddMount("/alpine", llb.Image("alpine:latest"), llb.Reado

31. BuildKit
buildkitd & buildctl
gRPC API
Go client library
rootless execution
OpenTracing
multi-worker model

32. BuildKit
buildkitd & buildctl
gRPC API
Go client library
rootless execution
OpenTracing
multi-worker model

33. BuildKit
buildkitd & buildctl
gRPC API
Go client library
rootless execution
OpenTracing
multi-worker model
containerd
worker
oci worker
buildkitd

34. BuildKit
Architecture

35. Architecture
Completely new design
LLB: Low-level intermediate build format
Side-effect free

36. Architecture
LLB Format
Describes a real dependency graph
Intermediate machine generated format
Content addressable protobuf
Unlimited inputs and outputs per vertex

37. Architecture
LLB Solver
Find most optimal execution path
Build up cache for repeated invocations
- based on secure root node checksums
- checksums by definition and content
- smart remote registry cache sources
Supports nested invocation

38. LLB Solver
Built to scale
https://github.com/tonistiigi/llb-gobuild

39. Architecture
LLB Authoring
Go client library
https://godoc.org/github.com/moby/buildkit/client/llb
llb.Image("alpine:latest").
AddEnv("FOO", "BAR").
Dir("/dir").
Run(llb.Shlex("ls -l"), llb.AddEnv("key", "val"))
r := Run(llb.Shlex("..."))
r.AddMount("/alpine", llb.Image("alpine:latest"), llb.Readonly)

40. BuildKit
Frontends
Convert any definition into LLB
Distributable as container images
Example: Dockerfile
Anyone can create a new frontend
Doesn’t need to be anything like Dockerfile

41. BuildKit
Dockerfile frontend
Automatically picks up all LLB concurrency/cache features
Fully compatible with current Docker
New: stages build in parallel
New: unused stages skipped
New: incremental build context updates
New: detecting context paths used by ADD/COPY
New: syntax directive

42. BuildKit
Dockerfile experimental features
Problem: Very hard to add new features
All changes are forever
Requires daemon upgrade
Breaks users / CI that have not updated
Solution: Load updates from images using frontends feature

43. BuildKit
Dockerfile syntax directive
- If present the remote frontend is used instead
- User can choose to rely on experimental features
… or use channel that is backwards compatible
- Everyone automatically gets the correct version
- Easy to develop because of limited scope
# syntax = registry/user/repo:tag

44. Dockerfile syntax directive
Example: RUN --mount
Access files directly from build
context or between the stages
Persistent special cache mounts
allow application specific caching.

45. BuildKit
DEMO
BuildKit in Docker
RUN --mount

46. 33.1x
10.6x
8.1x
Dockerfile syntax directive
Example: RUN --mount
moby/buildkit Dockerfile: time to binary rebuild after code change
slower
slower
slower
Measured on DO 4vcpu droplet

47. BuildKit
Get involved
Try Docker CE v18.06 and provide feedback
- export DOCKER_BUILDKIT=1
- Release later this month
https://github.com/moby/buildkit
#buildkit Docker community slack

48. Thanks! Questions?