OTE-Stack is an edge computing platform for 5G and AI

OTE-Stack

OTE-Stack is an edge computing platform for 5G and AI. By virtualization it can shield heterogeneous characteristics and gives a unified access of cloud edge, mobile edge and private edge. For AI it provides low-latency, high-reliability and cost-optimal computing support at the edge through the cluster management and intelligent scheduling of multi-tier clusters. And at the same time OTE-Stack makes device-edge-cloud collaborative computing possible.

Note: OTE-Stack is a heavy work in progress.

Advantages

Large scale and hierarchical cluster management

Through the standard interface, hierarchical clusters can be built quickly. The number of clusters can be theoretically unlimited which can effectively solve the management and scheduling problems of large-scale mobile edge clusters in 5G era.

Support third cluster

It supports kubernetes and k3s now. Because edge is a logical cluster，it can support any clusters by cluster-shim in theory. So in 5G era, it can be compatible with different implementations of different operators’MEC platforms. Use k8s cluster shim for both k8s and k3s when WebFrontend is used. k3s cluster shim is a lightweight version of k8s cluster shim without edge resource reporter. For better k3s support, we commit a pull request to make flannel config template, and offer a way to support GPU with k3s.

Lightweight cluster controller

Only one component and one customize shim can make the third cluster controlled by OTE-Stack. So it’s very light and easy to use.

Cluster autonomy

The edge is a complete logical cluster which caches almost all the states. So it will run normally when it is disconnected from the center which can effectively solve the problem of cluster autonomy in the case of weak edge networks.

Automatic disaster recovery

Because of the hierarchical design of clusters, Cluster Controller at each level will automatically acquire the alternate nodes. Once the connection with the parent node is lost, the connection with the center will be restored through the alternate nodes.

Global scheduling

Through Cluster Controller, all the clusters can be integrated into the unified scheduling, and the global optimal use of edge resources can be achieved.

Support multi-runtimes

OTE-Stack leverages virtlet for VM-based workloads, and also adds VM operation(start，stop, mount，etc.) via CustomResourceDefinition. So it supports VM，Kata containers and runc which can orchestrate in a unified way. Also, kubevirt can be used to manage VMs inside edge cluster with better support for GPU. WebFrontend of OTE-Stack would support VM operations in future work.

Kubernetes native support

With OTE-Stack, users can orchestrate dockers/VM on Edge clusters just like a traditional kubernetes cluster in the Cloud.

Support multi-arch

OTE-Stack can run on both x86 and arm architecture. All components of OTE-Stack has been tested on arm except GPU support. Images are avalible on docker hub.

Support edge autonomy

OTE-Stack has the autonomy of edge nodes and supports edge autonomy of k8s and k3s clusters.

Architecture

OTE-Stack features a pluggable architecture, making it much easier to build on.

• The global scheduler is fully compatible with kubernetes. Users can operate directly using kubectl;
• Using websocket for the edge-cloud communication;
• In addition to the cluster name, the cluster tag can be added customically. Cluster tag matching through intelligent cluster-selecter to achieve accurate routing of messages;
• Through k8s-cluster-shim to achieve the management of kubernetes cluster, shielding the native implementation within the kubernetes cluster;
• According to the interface of OTE-Stack, the cluster shim of the third party cluster can be realized to access and schedule the third party cluster. The internal implementation of the third party cluster is shielded;
• Each layer can be used as a control entry to control all sub-clusters below this layer. Users can also use kubectl or API to implement custom cluster management and scheduling.

On the edge, OTE-Stack provides the ability to support node autonomy within the cluster.

• Use EdgeHub to take over the kubelet, kube-proxy or k3s agent components of the node.
• EdgeHub provides load balancing capabilities for node requests.
• During node autonomy, you can use EdgeController instead of node to complete node status reporting and updating.
• EdgeHub and EdgeController have both the autonomy capabilities of k8s and k3s clusters.

Components

• WebFrontend
• WebBackend
• OpenAPI
• Scheduler
• ChartManager
• EdgeTunnel

Northbound interface of Controller. By establishing websocket connection with CloudTunnel of upper cluster, messages between clusters can be transmitted smoothly.

• EdgeHandler

It can add tags to cluster, receive and process messages from upper cluster, transmit messages to ClusterHandler, receive messages from ClusterHandler and realize cluster disaster recovery automatically.

• Users can configure their own cluster name or add cluster tags to achieve complex cluster management.
• Used for receiving messages sent by EdgeTunnel and forwarding them to Cluster Selecter for routing or direct transmission to ClusterHandler after processing.
• Receive messages sent back by ClusterHandler or shim (such as changes in sub-cluster, status, etc.) and pass them to the upper cluster through EdgeTunnel after processing.
• Once the connection between the current cluster and the parent cluster is established, the sibling cluster of the parent, the parent cluster of the parent and the sibling cluster of itself will be automatically acquired as the alternative cluster. When Disconnected，the alternative one is connected automatically. The connection to the central can be quickly restored. Meanwhile, it regularly checks whether the previous parent cluster is restored, and once restored, it restores the previous connection topology.
• ClusterSelecter

It is used to complete the routing of cluster messages, and it accepts the processing of two kinds of cluster routing rules.

• If it is a real list of cluster names, it matches the names according to the cluster routing rules and looks for the next hop until it reaches the specified cluster accurately.
• If it’s a cluster’s fuzzy rules, such as* tagA*, it matches all tagA-containing clusters in the tag and maps them to the real names of the clusters. Then it uses the above rules to pass down until it reaches the specified cluster accurately.
• ClusterHandler

It’s core components of cluster management.

• Store the names and labels of all subclusters.
• Establish routing rules that store the next hop cluster name to any sub-cluster to support accurate delivery of messages.
• Notify the upper cluster in time when the sub-cluster changes (such as disconnection, status updates, etc.)
• CloudTunnel

Southbound interface of Controller. By establishing websocket connection with EdgeTunnel of sub-cluster, messages between clusters can be transmitted smoothly.

• k8s-cluster-shim

It is an adapter of kubernetes cluster, which receives and parses cluster messages forwarded by OTE Cluster Controller, sends them to kubernetes cluster for corresponding processing, and returns the results and status to OTE Cluster Controller in time.

• k3s-cluster-shim

It is an adapter of k3s cluster, which receives and parses cluster messages forwarded by OTE Cluster Controller, sends them to k3s cluster for corresponding processing, and returns the results and status to OTE Cluster Controller in time.

• NodeAgent

It is deployed on edge nodes to retrieve data from cAdvisor and Node-Exporter which will be uploaded to NodesServer in edge clusters.

• NodesServer

In the edge cluster, it is used to aggregate data of each node and provide it to Prometheus (Prometheus can also directly collect data of the node, but requires the node to open the corresponding ports)

• DataQueryServer

Exposing Prometheus data as APIs to OpenAPI and Scheduler

• VMController

Operations for a single VM, such as start, stop, etc.

• EdgeHub

Proxy between master and node in the edge cluster.

• EdgeController

It is used to take over the state management of the node when the node is disconnected from the master.

Current Features

• Hierarchical cluster management
• Support kubernetes and k3s cluster by given shim
• Duplex channel from center to edge cluster
• Cluster autonomy
• Automatic disaster recovery(Previous topology is not yet restored)
• Kubernetes native support and it’s optional choice
• Accurate routing of messages between clusters

Getting Started

Quick Start

Build from source

Use for edge autonomy

TODO

OTE-Stack aims to providing a complete solution to edge cloud, so we will gradually open and improve the following core functions in the future.

Add Cluster Tags

By adding some tags for edge cluster, you can achieve complex cluster management.

Lightweight Edge Cluster

Although k3s and kubeedge have provided reference designs for edge clusters and their design ideas are ingenious, we will still explore how lightweight clusters suitable for edge infrastructure can be designed to better support edge clouds.

Edge Cluster Interface Standard

We need to consider the scheme of edge cluster and the design of 5G MEC(Multi-access Edge Computing) to abstract the interface and form the access standard of edge cluster. Now provider interface of virtual kubelet may be a candidate for us and we’ll try to see if it meets all our requirements.

Global Scheduling Strategy

Because the realization of sub-clusters is different, we need to consider how to use limited data on the basis of hierarchical clusters to schedule resources reasonably to meet the purpose of maximizing the utilization of edge cloud resources.

Message Routing Policy

In order to ensure the accurate delivery of messages, it is necessary to design the shortest path algorithm combining with the topological rules to reduce the transmission of useless messages.

We will also focus on and provide reference designs for other modules, such as Micro-Service framework, automation operation and maintenance of large-scale edge cluster, multi-tenant for edge cloud and Device-Edge-Cloud cooperation.

Contributing

If you’re interested in being a contributor and want to get involved in developing the OTE-Stack code, please see CONTRIBUTING for details on submitting patches and the contribution workflow.

Discussion

Email: ote-stack@baidu.com

License

OTE-Stack is under the Apache 2.0 license. See the LICENSE file for details.