virtuakube

Virtuakube

This project is no longer being developed. I'm leaving it online for historical interest, but you should not expect it to work, and definitely not expect support, fixes, or features.

Virtuakube sets up virtual Kubernetes clusters for testing.

It has several advantages compared to minikube or cloud clusters:

• Support any number of nodes, limited only by system RAM.
• Can run without root privileges (sort of - currently still requires docker privileges for image building).
• Can run without internet access.
• Because it emulates a full ethernet LAN, can be used to test networked systems.
• After initial setup, can recreate a complex VM and network topology in <10s, ideal for running lots of unit tests.

It's a very young system, and is being built for the needs of testing MetalLB, but seems like it could be generally useful for both playing with Kubernetes and testing scenarios. However, as of now you should expect the API to change frequently. Users and contributions are welcome, but be aware you're using a very young piece of software.

Your host machine must have qemu, qemu-img, vde_switch and guestfish installed.

Example usage

The CLI under cmd/vkube is a quick way to get started. All resources in virtuakube live in a Universe. Within a universe there are three resources: Images are base disk images for VMs, VMs are machines that can talk to each other and the internet, and Clusters are Kubernetes clusters bootstrapped on VMs.

First, let's create a universe and build a VM base image inside it:

vkube newimage --universe ./my-test-universe --name base

This will create the my-test-universe directory to store universe state, and build a VM base disk that contains Kubernetes tools and prepulled control plane images. Building the image takes about 5 minutes.

Once we've done that, we can run a cluster in our universe:

vkube newcluster --universe ./my-test-universe --name example --image base

Bootstrapping a cluster takes a couple of minutes, but when done vkube will print something like:

Created cluster "example"
Done (took 1m32s). Resources available:

  Cluster "example": export KUBECONFIG="/home/dave/my-test-universe/cluster/example/kubeconfig"
  VM "example-controller": ssh -p50000 root@localhost
  VM "example-node1": ssh -p50003 root@localhost

Hit ctrl+C to shut down

From there you can use the cluster as you wish, or SSH into VMs to do more stuff. The VMs created here are ephemeral, so when you ctrl+C they will be deleted, and you'll have to run newcluster again to rebuild it.

If you want to suspend and resume your cluster instead of creating/deleting, just add --save to the commandline. With --save, all running VMs will be snapshotted to disk, and will all resume as if nothing happened the next time the universe is opened. To open a universe and resume whatever was saved, but without creating new resources, use the resume command:

vkube resume --universe ./my-test-universe

Assuming you created and saved a cluster previously, you'll get familiar output:

Done (took 791ms). Resources available:

  Cluster "example": export KUBECONFIG="/home/dave/my-test-universe/cluster/example/kubeconfig"
  VM "example-controller": ssh -p50000 root@localhost
  VM "example-node1": ssh -p50003 root@localhost

Hit ctrl+C to shut down

The cluster is back, but this time it took less than a second to come up (your mileage may vary, depending on disk and CPU performance - but it should be much faster than creating VMs from scratch).

All vkube commands accept --save to mean "resume from the current state next time, instead of reverting to the last savepoint. Saving is off by default for all commands except newimage (which is why the base image we created stuck around - vkube implicitly saved the universe after creating the image).

All vkube commands accept --wait. If --wait is true, vkube will pause after the requested command has executed, print the available resources (as above), and wait for ctrl+C before closing the universe (with or without saving, depending on --save). Waiting is on by default for all commands except newimage.

So, if you wanted to non-interactively create a universe, build a base image, build a cluster and then immediately save it for future use, you'd run:

vkube newimage --universe ./my-new-universe --name base
vkube newcluster --universe ./my-new-universe --name example --image base --save --wait=false

Then, later, play with your cluster:

vkube resume --universe ./my-new-universe