Stop killing kittens and melting ice capsRun containers on bare metal already!

CTO

bryan@joyent.com

Bryan Cantrill

@bcantrill

Container prehistory

• Containers are not a new idea, having originated via filesystem containers with chroot in Seventh Edition Unix

• chroot originated with Bill Joy, but specifics are blurry; according to Kirk McKusick, via Poul-Henning Kamp and Robert Watson:

Container history

• Seeking to provide a security mechanism, FreeBSD extended chroot into jails:

• To provide workload consolidation, Sun introduced complete operating system virtualization with zones (née Project Kevlar)

Container history

Container limitations

• The (prioritized) design constraints for OS-based virtualization as originally articulated by zones: Security, Isolation, Virtualization, Granularity, Transparency

• Not among these: running foreign binaries or emulating other operating systems!

• Despite its advantages in terms of tenancy and performance, OS-based virtualization didn’t fit the problem ca. early 2000s: needed the ability to consolidate entire stacks (i.e. Windows)

Hardware-level virtualization

• Since the 1960s, the preferred approach for operating legacy stacks unmodified has been to virtualize the hardware

• A virtual machine is presented upon which each tenant runs an operating system that they choose (but must also manage)

• Effective for running legacy stacks, but with a clear inefficiency: there are as many operating systems on a machine as tenants:

• Operating systems are heavy and don’t play well with others with respect to resources like DRAM, CPU, I/O devices, etc.!

• Still, hardware-level virtualization became de facto in the cloud

Containers at Joyent

• Joyent runs OS containers in the cloud via SmartOS — and we have run containers in multi-tenant production since ~2006

• Adding support for hardware-based virtualization circa 2011 strengthened our resolve with respect to OS-based virtualization

• OS containers are lightweight and efficient — which is especially important as services become smaller and more numerous: overhead and latency become increasingly important!

•We emphasized their operational characteristics — performance, elasticity, tenancy — and for many years, we were a lone voice...

Containers as PaaS foundation?

• Some saw the power of OS containers to facilitate up-stack platform-as-a-service abstractions

• For example, dotCloud — a platform-as-a-service provider — built their PaaS on OS containers

• Struggling as a PaaS, dotCloud pivoted — and open sourced their container-based orchestration layer...

...and Docker was born

Docker revolution

• Docker has used the rapid provisioning + shared underlying filesystem of containers to allow developers to think operationally

• Developers can encode deployment procedures via an image

• Images can be reliably and reproducibly deployed as a container

• Images can be quickly deployed — and re-deployed

• Docker complements the library ethos of microservices

• Docker will do to apt what apt did to tar

Broader container revolution

• The Docker model has pointed to the future of containers

• Docker’s challenges today are largely operational: network virtualization, persistence, security, etc.

• Security concerns are not due to Docker per se, but rather to the architectural limitations of the Linux “container” substrate

• For multi-tenancy, state-of-the-art for Docker containers is to run in hardware virtual machines as Docker hosts (!!)

• Deploying OS containers via Docker hosts in hardware virtual machines negates their economic advantage!

Container-native infrastructure?

• SmartOS has been container-native since its inception — and running in multi-tenant, internet-facing production for many years

• Can we achieve an ideal world that combines the development model of Docker with the container-native model of SmartOS?

• This would be the best of all worlds: agility of Docker coupled with production-proven security and on-the-metal performance of SmartOS containers

• But there were some obvious obstacles...

Docker + SmartOS: Linux binaries?

• First (obvious) problem: while it has been designed to be cross-platform, Docker is Linux-centric — and the encyclopedia of Docker images will likely forever remain Linux binaries

• SmartOS is Unix — but it isn’t Linux…

• Fortunately, Linux itself is really “just” the kernel — which only has one interface: the system call table

•We resurrected (and finished) a Sun technology for Linux system call emulation, LX-branded zones, the technical details of which are beyond the scope of this presentation...

LX-branded zones: tl;dr

LX-branded zones: tl;dr, cont.

LX-branded zones: tl;dr

LX-branded zones: tl;dr, cont.

LX-branded zones: tl;dr, cont.

Docker + SmartOS: Provisioning?

•With the binary problem being tackled, focus turned to the mechanics of integrating Docker with SmartOS provisioning

• Provisioning a SmartOS zone operates via the global zone that represents the control plane of the machine

• docker is a single binary that functions as both client and server — and with too much surface area to run in the global zone, especially for a public cloud

• docker has also embedded Go- and Linux-isms that we did not want in the global zone; we needed to find a different approach...

Aside: The power of an interface

Aside: The power of an interface

Aside: The power of an interface

Aside: The power of an interface

Docker Remote API

•While docker is a single binary that can run on the client or the server, it does not run in both at once…

• docker (the client) communicates with docker (the server) via the Docker Remote API

• The Docker Remote API is expressive, modern and robust (i.e. versioned), allowing for docker to communicate with Docker backends that aren’t docker

• The clear approach was therefore to implement a Docker Remote API endpoint for SmartDataCenter, our (open source!) orchestration software for SmartOS

Triton: Docker + SmartOS

• In March, we launched Triton, which combines SmartOS and SmartDataCenter with our Docker Remote API endpoint

•With Triton, the notion of a Docker host is virtualized: to the Docker client, the datacenter is a large Docker host

• One never allocates VMs with Triton; all Triton containers are run directly on-the-metal

• All of the components to Triton are open source: you can download and install SmartDataCenter and run it yourself

• Triton is currently general available on the Joyent Public Cloud!

Container landscape

• It is becoming broadly clear that containers are the future of application development and deployment

• But the upstack ramifications are entirely unclear — there are many rival frameworks for service discovery, composition, etc.

• The rival frameworks are all open source:

• Unlikely to be winner-take-all

• Productive mutation is not just possible but highly likely

• Triton takes a deliberately modular approach: the container as general-purpose foundation, not prescriptive framework

Realizing the container revolution

• The container revolution extends beyond traditional computing — it changes how we think of computing with respect to other elements of the stack

• e.g. container-centric object storage allows us to encapsulate computation as containers that can process data in situ — viz. Joyent’s (open source!) Manta storage service

• Realizing the full container revolution requires us to break the many-to-one relationship between containers and VMs!

Future of containers

• For nearly a decade, we have believed that OS-virtualized containers represent the future of computing — and with the rise of Docker, this is no longer controversial

• But to achieve the full promise of containers, they must run directly on-the-metal — multi-tenant security is a constraint!

• The virtual machine is a vestigial abstraction; we must reject container-based infrastructure that implicitly assumes it

• Triton represents our belief that containers needn’t compromise: multi-tenant security, operational elasticity and on-the-metal performance!