ClusterLink Project

Disclaimers and Warnings

This is an incomplete work in progress, provided in the interest of sharing experience and gathering feedback. The code is pre-alpha quality right now. This means that it shouldn't be used in production at all.

Before settling on the ClusterLink name. the code base was previously developed as part of a "Multi-Border Gateway" concept exploration. You may still find various places in code and documentation referring to the old name (directly or using the MBG acronym). We're in the process of changing all such references.

What Is ClusterLink?

The ClusterLink project simplifies the connection between application services that are located in different domains, networks, and cloud infrastructures.

For more details, see the document: ClusterLink extended abstract.

ClusterLink deploys a gateway into each location, facilitating the configuration and access to multi-cloud services. The ClusterLink gateway contains the following components:

1. Control Plane is responsible for maintaining the internal state of the gateway, for all the communications with the remote peer gateways by means of the ClusterLink CP Protocol (REST APIs), and for commanding the local DP to forward user traffic according to policies. Part of the control plane is the policy engine that can also apply network policies (ACL, load-balancing, etc.)
2. Data Plane responds to user connection requests, both local and remote, initiates policy resolution in the CP, and maintains the established connections. ClusterLink DP relies upon standard protocols and avoids redundant encapsulations, presenting itself as a K8s service inside the cluster and as a regular HTTP endpoint from outside the cluster, requiring only a single open port (HTTP/443) and leveraging HTTP endpoints for connection multiplexing.
3. gwctl is CLI implementation that uses REST APIs to send control messages to the ClusterLink Gateway.

The ClusterLink APIs use the following entities for configuring cross cluster communication:

• Peer. Represent remote ClusterLink gateways and contain the metadata necessary for creating protected connections to these remote peers.
• Exported service. Represent application services hosted in the local cluster and exposed to remote ClusterLink gateways as Imported Service entities in those peers.
• Imported service. Represent remote application services that the gateway makes available locally to clients inside its cluster.
• Policy. Represent communication rules that must be enforced for all cross-cluster communications at each ClusterLink gateway.

Getting Started

WIP; combine with sections below. Some details should probably be moved into their own documents.

How to setup and run ClusterLink

ClusterLink can be set up and run on different environments: local environment (Kind), Bare-metal environment, or cloud environment.

Run ClusterLink in local environment (Kind)

ClusterLink can run in any K8s environment, such as Kind. To run the ClusterLink in a Kind environment, follow one of the examples:

1. Performance example - Run iPerf3 test between iPerf3 client and server using ClusterLink components. This example is used for performance measuring. Instructions can be found Here.
2. Application example - Run the BookInfo application in different clusters using ClusterLink components. This example demonstrates communication distributed applications (in different clusters) with different policies.Instructions can be found Here.

Run ClusterLink in Bare-metal environment with 2 hosts

TBD

Run ClusterLink in cloud environment

TBD

Contributing

Our project welcomes contributions from any member of our community. To get started contributing, please see our Contributor Guide.

Scope

In Scope

ClusterLink is intended to [TODO: Core functionality]. As such, the project will implement or has implemented:

• [TODO: High-level Item 1]
• [TODO: High-level Item 2]
• [TODO: High-level Item 3]

Out of Scope

ClusterLink will be used in a cloud native environment with other tools. The following specific functionality will therefore not be incorporated:

• [TODO: Excluded function 1]
• [TODO: Excluded function 2]

ClusterLink implements [TODO: List of major features, existing or planned], through [TODO: Implementation requirements/language/architecture/etc.]. It will not cover [TODO: short list of excluded items]

Communications

[TODO: Details (with links) to meetings, mailing lists, Slack, and any other communication channels]

• User Mailing List:
• Developer Mailing List:
• Slack Channel:
• Public Meeting Schedule and Links:
• Social Media:
• Other Channel(s), If Any:

Resources

[TODO: Add links to other helpful information (roadmap, docs, website, etc.)]

License

This project is licensed under [TODO: Add name of license and link to your LICENSE file]

Conduct

We follow the CNCF Code of Conduct [TODO: Insert link to your CODE_OF_CONDUCT.md file].