Docker and Kubernetes will accelerate SDN development

Docker and its container concepts quickly change the way people build applications in cloud computing environments. These changes also have an impact on the network, and the container seems likely to use software to define the functionality of the network.

This is because containers enable developers to rethink the way they use computer capabilities-new methods require higher levels of network abstraction technology. This can be discerned from Google's Kubernetes project, which has been open source in June 2014, and can use a proxy technique (which can be categorized as SDN).

"In my opinion, networking, storage, and security will be further closer to a Docker container than a separate application," Docker CEO Ben Golub said. Gradual, such as load balancing or bridging tasks will be done using containers to the container (Container-to-container), rather than machine to machine (machine-to-machine) mode.

The container is getting really cool.

Officially launched in March 2013, Docker defines a container that accommodates applications (including their dependencies: binaries and libraries) that can exist on any physical or virtual Linux server. In fact, prior to the advent of Docker, companies like Google are already using container technology, but the presence of Docker makes the containers standardized and easier to use.

Golub illustrated the problem with a metaphor: Before Docker, there were a lot of steel boxes, but the size was just right, and the boxes in the right place were Docker.

Complex applications can "spread" across multiple containers, but ensuring that these containers communicate with each other creates another technological innovation: Open source Docker container management and choreography technology. Kubernetes and Mesos are the representatives, Docker also developed their own version libswarm, and provided a common interface.

In fact, Docker is trying to unify these solutions with Libchan, Libchan is a library of build complex network services, Golub said: "We are trying to provide generic but not too rigid interface."

People in the Open vswitch and OpenFlow camps have also started working on networking Docker, Golub said. Ideally, a container can define what it needs on the network, the ports it uses, and other containers that need to be communicated.

Service the application through a proxy (serving Apps by proxy)

Kubernete has a special networking concept that is very similar to SDN: A Service Broker that creates an IP address that can be assigned to any number of containers (fan out).

June Open Source, Kubernetes is an open source derivation of Borg. Borg is a Google tool that allows developers to pool computing power from a large number of decentralized data centers. Kubernetes received some heavyweight support: coreos,docker,ibm,mesosphere,microsoft,red hat and Saltstack.

Brendan Burns says the idea of service proxies is a turning point in Network abstraction technology. Brendan Burns is one of the two engineers who started the Kubernetes project.

Kubernetes uses an agent method that obtains its own IP address through a special service (defined as a cross container query). Behind this address may be a large stack of containers that provide the same services. However, at the front end, the application or the user using the service invokes the service only through this IP address.

This means that the number of containers running a service can be increased or reduced as needed, and the customer or the application that uses the service does not need to care about these details. As can be imagined, if the service is a mobile network back-end process, when traffic surges, a large number of containers will be added to the service, once the traffic returns to normal, then remove the excess containers. Discovering the services that a particular container is running, and the load balancing between these containers, will be done in the background. Without this proxy service, you can add more containers, but you have to tell users and applications for these details. Google's approach eliminates this configuration requirement.

Burns said: "In a sense, this proxy method, can proxy any given service (in the kubernetes sense), these services can come from its own network." “

This proxy scheme is somewhat SDN, although it is not built on a typical SDN-related PP layer mechanism. "This is a binary we write. It does not use OvS or anything similar to OvS, Burns says, but we anticipate that when SDN becomes more common, it (a binary we write) will be replaced by SDN technology.