flowScheduler implemented with kubernetes A Firmament Prototype

Firmament is a new apporach to cluster scheduling that models the problem of scheduling as a network flow optimization problem. Firmament aims on providing:

• Policy optimal scheduling
• Lower latency on scheduling decisions
• Flexibility through pluggable policies

Ksched is an experimental reimplementation of the scheduler from it's C++ implementation to Go. The goal of this project is to integrate Firmament in Kubernetes as an alternative scheduler.

The project so far is an early stage prototype with all the mechanisms for performing multiple scheduling iterations.

The scheduler layer has a minimal interface with the Kubernetes API allowing it to batch schedule pods. Currently the implementation has no support for sophisticated policies and will perform a trivial first-fit policy to assign pods to nodes in the cluster.

To get the scheduler up and running there are two ways to currently test it out.

You can test the scheduler by running it inside of a container on the kubernetes master node. You can build the image from build/Dockerfile yourself or as described below use our hosted image.

On the master node pull the image.

docker pull hasbro17/ksched:v0.6

Run the container on the host network, waiting in background mode.

docker run --net="host" --name="ksched" -d hasbro17/ksched:v0.6 tail -f /dev/null

You will need to pause the pre-existing kubernetes scheduler's container before trying to run ksched.

docker pause <container-ID>

Get a shell into the ksched container.

docker exec -it ksched /bin/bash

Run the init script to clone and build the scheduler.

/root/init.sh

There should be two binaries present in the ksched project at /root/go-workspace/src/github.com/coreos/ksched

The first k8sscheduler, is the scheduler whose flags are specified in cmd/k8sscheduler/scheduler.go. Run this binary to start the scheduler.

k8sscheduler -fakeMachines=false

The scheduler should start up and wait for unscheduled pods at this point.

To generate a large number of pod requests you can use the binary podgen.

podgen -numPods=<number-of-pods> -image=nginx

You can test the scheduler without the real cluster by only having the kube-api binary running. The setup is a little more involved for this case.

You will need to have the same environment set up as is for the ksched image described by build/Dockerfile. Use that as a guide for your setup.

• Setup the Flowlessly solver binary in the correct location: /usr/local/bin/flowlessly/.
• Setup the Kubernetes(v1.3) source at the following location in your go workspace: $GOPATH/src/k8s.io
• Get the ksched source: go get github.com/coreos/ksched (or from the mirror repo github.com/hasbro17/ksched-mirror)
• Generate the proto files by running proto/genproto.sh