Banzai Cloud is now part of Cisco

Banzai Cloud Logo Close
Home Products Benefits Blog Company Contact

The content of this page hasn't been updated for years and might refer to discontinued products and projects.

During the development of the Pipeline Platform all of its key building blocks such as Pipeline, Hollowtrees and Bank-Vaults have relied on making extensive Kubernetes API calls. Often, we tried a quick K8s API call or ran a small PoC inside a cluster, while also wanting to avoid the usual deployment process. We quickly realized that we needed a shortcut.

There are tools like telepresence that support slightly more complex scenarios. However, for simple hacks they tend toward overkill - require osxfuse, use VPN + ssh to make the network available, etc - whereas, when making a quick and dirty API call, this 21 lines of bash script does the job.

kurun is like go run πŸ”—︎

The go run command is a very convenient CLI subcommand for executing Golang code during the development phase. Many of our applications make calls to the Kubernetes API and for a long time we were in need of a utility that could very quickly execute the Go code inside Kubernetes. That’s why we wrote kurun, a dirty little bash utility, to execute Go code inside Kubernetes with a oneliner:

kurun main.go

It’s that easy.

To see how you can leverage kurun, let’s try, just as an example, using it to list all the nodes in a Kubernetes cluster:

 1package main
 2
 3import (
 4	"fmt"
 5	"os"
 6
 7	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 8	"k8s.io/client-go/kubernetes"
 9	"k8s.io/client-go/rest"
10)
11
12func main() {
13	fmt.Println(os.Args)
14
15	config, err := rest.InClusterConfig()
16	if err != nil {
17		panic(err)
18	}
19
20	client, err := kubernetes.NewForConfig(config)
21	if err != nil {
22		panic(err)
23	}
24
25	nodes, err := client.CoreV1().Nodes().List(metav1.ListOptions{})
26	if err != nil {
27		panic(err)
28	}
29
30	fmt.Println("List of Kubernetes nodes:")
31	for _, node := range nodes.Items {
32		fmt.Printf("- %s - %s\n", node.Name, node.Labels)
33	}
34}

Execute the following commands in the CLI, and make sure your kubectl is pointed to the cluster you would like to use:

 1git clone git@github.com:banzaicloud/kurun.git
 2cd kurun
 3# Download the dependencies, this is just a one-time step to get the k8s libraries
 4go get ./...
 5./kurun test.go
 6Sending build context to Docker daemon  31.05MB
 7Step 1/2 : FROM alpine
 8 ---> 3fd9065eaf02
 9Step 2/2 : ADD main /
10 ---> 0f4ee24ec5ea
11Successfully built 0f4ee24ec5ea
12Successfully tagged kurun:latest
13[/main]
14List of Kubernetes nodes:
15- docker-for-desktop - map[beta.kubernetes.io/arch:amd64 beta.kubernetes.io/os:linux kubernetes.io/hostname:docker-for-desktop node-role.kubernetes.io/master:]

Learn by the code πŸ”—︎

This project is open source and, of course, available in our GitHub repository.