#kubernetes #nix #nix-shell #crio #kube

bin+lib kubernix

Kubernetes development cluster bootstrapping with Nix packages

2 releases

0.1.1 Oct 3, 2019
0.1.0 Oct 3, 2019

#1084 in Command line utilities

MIT license

96KB
1.5K SLoC

CircleCI Docs master Docs release Coverage Dependencies Crates.io License MIT

Kubernetes development cluster bootstrapping with Nix packages

This project aims to provide you single dependency, single node Kubernetes clusters for local testing, experimenting and development purposes.

About

Do you ever heard from Nix, the functional package manager? Don't worry if not, all you need to know is that it provides all the third party dependencies for this project, pinned to a dedicated and reproducible version.

KuberNix itself is the Rusty helper program, which takes care of bootstrapping the Kubernetes cluster, passing the right configuration parameters around and keeping track of the running processes.

What is inside

The following technology stack is currently being used:

Application  Purpose Version
Kubernetes Cluster Orchestration v1.15.4
CRI-O Container Runtime v1.15.2
runc Container Runtime v1.0.0-rc8
cri-tools CRI Manipulation Tool v1.15.0
CNI Plugins Container Networking v0.8.2
etcd Database Backend v3.3.13
CoreDNS Kubernetes DNS Support v1.6.4

Some other tools are not explicitly mentioned here, like CFSSL for the certificate generation.

Single Dependency

As already mentioned, there is only one single dependency needed to run this project: Nix. To setup Nix, simply run:

$ curl https://nixos.org/nix/install | sh

Please make sure to follow the instructions output by the script.

Getting Started

Cluster Bootstrap

To bootstrap your first cluster, download one of the latest release binaries or build the application via:

$ make build-release

The binary should now be available in the target/release/kubernix directory of the project.

After the successful binary retrieval, start KuberNix by running it as root:

$ sudo kubernix

KuberNix will now take care that the Nix environment gets correctly setup, downloads the needed binaries and starts the cluster. Per default it will create a directory called kubernix in the current path which contains all necessary data for the cluster.

Shell Environment

If everything went fine, you should be dropped into a new bash-shell session, like this:

[INFO  kubernix] Everything is up and running
[INFO  kubernix] Spawning interactive shell
[INFO  kubernix] Please be aware that the cluster gets destroyed if you exit the shell
>

Now you can access your cluster via tools like kubectl:

> kubectl get pods --all-namespaces
NAMESPACE     NAME                       READY   STATUS    RESTARTS   AGE
kube-system   coredns-85d84dd694-xz997   1/1     Running   0          102s

The log files for the different running components are now available within the current working directory, too:

> ls -1
crio.log
etcd.log
kube-apiserver.log
kube-controller-manager.log
kubelet.log
kube-proxy.log
kube-scheduler.log

If you want to spawn an additional shell session, simply run kubernix shell in the same directory as the initial bootstrap.

$ sudo kubernix shell
[INFO  kubernix] Spawning new kubernix shell in 'kubernix-run'
> kubectl run --generator=run-pod/v1 --image=alpine -it alpine sh
If you don't see a command prompt, try pressing enter.
/ #

This means that you can spawn as many shells as you want to.

Cleanup

The whole cluster gets automatically destroyed if you exit the bash session from the initial process:

> exit
[INFO  kubernix] Cleaning up

Please note that the directory where all the data is stored is not being removed after the exit of KuberNix. This means that you're still able to access the log and configuration files for further processing.

Configuration

KuberNix has some configuration possibilities, which are currently:

CLI argument Description Default
-r, --root Path where all the runtime data is stored kubernix-run
-l, --log-level Logging verbosity info
-c, --crio-cidr CIDR used for the CRI-O CNI network 10.100.0.0/16
-u, --cluster-cidr CIDR used for the whole cluster network 10.200.0.0/16
-s, --service-cidr CIDR used for the service network 10.50.0.0/24

Please ensure that the CIDRs are not overlapping with existing local networks and that your setup has access to the internet.

Contributing

You want to contribute to this project? Wow, thanks! So please just fork it and send me a pull request.

Dependencies

~8.5MB
~181K SLoC