Kubernetes is gaining popularity in container management, automating the deployment, upgrade and scaling of containerized applications. Kube-scheduler is the component to that decides the placement of pods onto a pool of worker machines called nodes. Kube-scheduler has a rich set of features, which allows users to specify resource constraint to pods as well as other policies. One of the most popular policies is pod affinity/anti-affinity, which allows users to specify pods that reside together or separately.
Pod affinity/anti-affinity policies are very useful when users want either pod adjacency for performance, or separation for redundancy. For example, users want 2 pods on the same host, so the communication between those pods are not traveling externally to network devices. A more critical use case is users want a 3-node etcd cluster to be deployed on 3 different nodes, so losing any one of them does not cause the cluster lose quorum. Both use cases require pod affinity and pod anti-affinity policy support from Kube-scheduler.
Everything should work perfectly if the Kubernetes cluster runs on physical nodes. However, when the cluster node is running on virtual machines (most likely it does), like on vSphere, things become more complicated. Take anti-affinity as an example, if all the etcd pods running on different virtual machines, but all virtual machines are running on the same physical host, does the policy give you any guarantee that you assume you would have? The answer is clearly no. This plugin is to extend Kubernetes scheduler so that it has both additional information from vSphere to help it making better affinity decisions.
Refer to this intro for more details.
This plugin is compatible with
- Kubernetes 1.8+
- vSphere 6.5+
Any Kubernetes distribution running on vSphere should be compatible with this plugin, no matter it's managed by PKS, tectonic, or any other tools. However, if you do find issues with compatibility, please let us know by submitting issues here.
Just running go build on the root folder of the project will compile into
vsphere-affinity-scheduling-plugin in the same folder.
Running go install will build and install it into your GOPATH.
make check will check the style by govet and golint.
make test will run unit tests.
make e2e will run e2e tests.
Check the CLI helper with ./vsphere-affinity-scheduling-plugin -h
The vsphere-affinity-scheduling-plugin project team welcomes contributions from the community. If you wish to contribute code and you have not signed our contributor license agreement (CLA), our bot will update the issue when you open a Pull Request. For any questions about the CLA process, please refer to our FAQ. For more detailed information, refer to CONTRIBUTING.md.
This software is available under Apache 2 license.