Community Blog A Quick View of OpenYurt v1.2: Cloud-Edge Traffic Peak Reduced by 90% Compared to Native Kubernetes

A Quick View of OpenYurt v1.2: Cloud-Edge Traffic Peak Reduced by 90% Compared to Native Kubernetes

This article highlights the release of OpenYurt v1.2.

By Linbo He (Technical Expert at Alibaba Cloud), Shaoqiang Chen (Senior Software Architect at Intel), and Lin Yu (Senior Software Engineer at Intel)

OpenYurt v1.2.0 was released on January 30, 2023. It implemented several features that the community has been demanding most. OpenYurt has more distinctive features. Its main features include Kubernetes non-intrusion, cloud-edge-terminal collaboration, programmable resource access control, and declarative cloud-native device management.

v1.2 focuses on node pool governance and aims to build the differentiated technical competitiveness of the OpenYurt system. The main features include reduced traffic cost of cloud-edge communication, enhanced edge autonomy, and smoother cross-region communication.

Significantly Reduced Traffic Cost of Cloud-Edge Communication

In the collaborative scene of the cloud edge, the edge is connected to the cloud through the public network. When a large number of business Pods and microservice systems are deployed in the cluster (introducing a large number of Services and Endpointslices), a large amount of bandwidth is consumed between the edge nodes and the cloud, which puts great pressure on the user's public network traffic cost.

The community has always had a strong demand for reducing cloud-edge communication traffic. How can we meet the demand without intruding and modifying Kubernetes? The first solution is to add a sync component in the node pool to synchronize cloud data in real-time and then distribute the cloud data to each component in the node pool. However, the implementation of this solution will face considerable challenges. First, data access requests are actively initiated by the edge to the cloud. How can the sync component intercept these requests and distribute data? If the sync component fails, requests from the edge will be interrupted, and it is quite difficult to ensure the high availability of the sync component.

The OpenYurt community pioneered the cloud-edge traffic reuse mechanism based on pool-coordinator+YurtHub. This mechanism seamlessly integrates with the cloud-edge communication links of native Kubernetes and ensures the high availability of communication links (YurtHub Leader election), reducing the cost of cloud-edge communication.

In a node pool, the data that nodes obtain from the cloud can be divided into two types:

  • pool scope data: The data that is the same as the data that components obtain from the cloud (such as the endpointslices obtained by the kube-proxy of each node)
  • node scope data: The data a component obtains from the cloud is related to its own nodes (such as the pods obtained by the kubelet of each node).

At the same time, through the test [1], it is found that the data that occupies the bandwidth of the cloud-edge communication is pool scope data. OpenYurt v1.2 significantly reduces the traffic cost of cloud-edge communication by reusing pool scope data in the node pool, as shown in the following figure:


  • The Leader is elected among all YurtHub components through the Pool-Coordinator in the node pool, and only the YurtHub component that is properly connected to the cloud network will become the Leader. If the cloud-edge network connection of the Leader node is abnormal, the Leader will be automatically replaced by a Follower.
  • The Yurthub Leader actively obtains pool scope data (such as Endpointslices) from the cloud in real-time and then stores the pool scope data in the Pool-Coordinator component in the node pool.
  • When a component (such as a Kube-Proxy) on a node uses Yurthub to obtain pool scope data, Yurthub returns real-time data from Pool-Coordinator.

Through the cooperation between Pool-Coordinator and Yurthub, there is only the pool scope data of cloud-side communication within a single node pool, thus significantly reducing the amount of cloud-edge communication data and the cloud outbound traffic peak by 90% compared to native Kubernetes.

In addition, it brings an interesting capability. Through traffic reuse of Endpointslices, even if edge nodes are disconnected from the cloud network, they can still perceive the service topology status of the cluster in real-time.

Enhanced Edge Autonomy Capability

Edge autonomy capability can ensure uninterrupted service provisioning from edge businesses in cloud-edge collaboration scenarios. The edge autonomy capability includes data caching at the edge side to ensure service recovery when nodes restart in the scenario of cloud-edge network disconnection. It also includes the enhancement of the eviction policy for Pods at the control side (cloud controller).

In native Kubernetes, if the heartbeat of an edge node has not been reported for a certain period, the cloud controller will evict the Pod on the node (delete and rebuild it on the normal node).

Edge businesses have different requirements in cloud-edge collaboration scenarios. The business requires that when the heartbeat cannot be reported due to the cloud-edge network disconnection (the node itself now is normal), the Pod can be maintained (no Pod eviction occurs), and the Pod is migrated and only rebuilt when the node fails.

Compared with the complex network situation of cloud-edge public network connection, the network connection is in good condition when the nodes in the same node pool are in the same local area network. A common solution in the industry is mutual network detection among edge nodes to build a distributed node health detection mechanism. However, the network detection in this solution will generate a large amount of east-west traffic and a certain amount of calculation on each node. As the size of the node pool increases, the detection effect will face certain challenges.

OpenYurt v1.2 provides a centralized heartbeat proxy mechanism based on pool-coordinator+YurtHub. This mechanism can reduce the east-west communication traffic in node pools and the overall computing power requirements and maintain Pod when the cloud-edge network is disconnected, as shown in the following figure:


  • When the cloud-edge network of a node is normal, Kubelet uses the YurtHub component to report the heartbeat to both the cloud and Pool-Coordinator.
  • When the cloud-edge network of a node is disconnected, Kubelet fails to report the heartbeat to the cloud through the YurtHub component. At this point, the heartbeat reported to Pool-Coordinator carries a specific tag.
  • Leader YurtHub will list or watch the heartbeat data in the pool-coordinator in real-time. When the obtained heartbeat data has a specific tag, Leader YurtHub will forward the heartbeat to the cloud.

The heartbeat proxy mechanism jointly implemented by Pool-Coordinator and YurtHub successfully ensures that the heartbeat can continue to be reported to the cloud when the cloud-edge network of a node is disconnected, thus ensuring that the business Pods on the node will not be evicted. At the same time, the node whose heartbeat is reported by the proxy, Leader YurtHub, will be added with special taints in real-time to restrict scheduling new Pod to this node.

Smoother Cross-Region Communication Capability

The Raven project of the OpenYurt community has evolved to v0.3. This project mainly provides a 3-layer cross-region communication capability. Compared with the SuperEdge provided by Yurt-Tunnel, which only supports 7-layer traffic forwarding from cloud to edge, Raven can provide a more general cross-region communication capability (cloud-edge interconnection/edge-to-edge interconnection), as shown in the following figure:


  • Select a Gateway node from each node pool (a Solo node automatically becomes a Gateway node). The Gateway node establishes a VPN tunnel through the cloud and configures traffic forwarding rules on each node through Raven.
  • Cross-node requests will be intercepted and forwarded to the Gateway node and then forwarded to the corresponding node or Pod through the VPN tunnel. At the same time, the access traffic in the node pool will not be intercepted, and the native CNI will be used to communicate.

The Raven solution is seamlessly compatible with the native CNI solution. Cross-region traffic forwarding is imperceptible to applications. Therefore, in cloud-edge and edge-to-edge cross-region communication, application mutual access in OpenYurt can maintain a consistent user experience in native Kubernetes. Starting from OpenYurt v1.2, we recommend using Raven instead of YurtTunnel.

Other Important Updates

  • The yurtadm component is optimized. The underlying component is implemented based on the kubeadm binary. It is compatible with the Kubernetes community. #1049[2]
  • Elegant upgrade proposal of edge static pod in cloud-edge collaboration scenarios #1065[3]
  • An inclusterconfig filter is introduced to ensure the kube-proxy access to kube-apiserver through YurtHub. #1158[4]
  • The problem that happens when YurtHub forwards Watch requests, the single returned data in response will be truncated when the data size exceeds 32KB is solved. #1066[5]


The development of OpenYurt v1.3 is progressing. If you are interested, you are welcome to participate in the co-construction to explore the de facto standard of a stable, reliable, and non-intrusive cloud-native edge computing platform.

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