kurun
- Just like
go run main.gobut executed inside Kubernetes with one command. - Just like
kubectl port-forward ...but the other way around! - Just like
kubectl apply -f pod.yamlbut images are built from local source code.
Synopsis
Usage:
kurun [command]
Available Commands:
apply Just like `kubectl apply -f pod.yaml` but images are built from local source code.
help Help about any command
port-forward Just like `kubectl port-forward ...` but the other way around!
run Just like `go run main.go` but executed inside Kubernetes with one command.
Flags:
-h, --help help for kurun
--namespace string Namespace to use for the Pod/Service (default "default")
Use "kurun [command] --help" for more information about a command.
Prerequisites
- A Kubernetes cluster, where you have access to the image storage of the cluster itself, for example:
- Docker for Mac Edge with Kubernetes enabled
- Minikube with the Registry addon enabled
- kubectl
Installation
Brew version
brew install banzaicloud/tap/kurunGo version
go get github.com/banzaicloud/kurunBinaries under releases
https://github.com/banzaicloud/kurun/releases
Usage
kurun run test.go arg1 arg2 arg3kurun port-forward localhost:4443kurun apply -f - <<EOF
apiVersion: v1
kind: Pod
metadata:
name: myapp
spec:
containers:
- image: kurun://cmd/myapp/main.go
name: myapp
EOFkurun is like go run to Kubernetes
The go run command is a convenient CLI subcommand for executing Golang code during the development phase. A lot of our applications are making calls to the Kubernetes API and we needed a quick utility to execute the Go code inside Kubernetes very quickly. That's why we have written kurun, a dirty little bash utility, to execute Go code inside Kubernetes with a oneliner:
kurun run main.go
It's that easy.
To see how you can leverage kurun letโs try checking it out with a small example which lists all nodes in your Kubernetes cluster:
package main
import (
"fmt"
"os"
metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
"k8s.io/client-go/kubernetes"
"k8s.io/client-go/rest"
)
func main() {
fmt.Println(os.Args)
config, err := rest.InClusterConfig()
if err != nil {
panic(err)
}
client, err := kubernetes.NewForConfig(config)
if err != nil {
panic(err)
}
nodes, err := client.CoreV1().Nodes().List(metav1.ListOptions{})
if err != nil {
panic(err)
}
fmt.Println("List of Kubernetes nodes:")
for _, node := range nodes.Items {
fmt.Printf("- %s - %s\n", node.Name, node.Labels)
}
}Execute the following commands in the CLI, make sure your kubectl points to the cluster you would like to use:
git clone [email protected]:banzaicloud/kurun.git
cd kurun
# Download the dependencies, this is just a one-time step to get the k8s libraries
go get ./...
./kurun run example/test.go
Sending build context to Docker daemon 31.05MB
Step 1/2 : FROM alpine
---> 3fd9065eaf02
Step 2/2 : ADD main /
---> 0f4ee24ec5ea
Successfully built 0f4ee24ec5ea
Successfully tagged kurun:latest
[/main]
List of Kubernetes nodes:
- 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:]kurun is like kubectl port-forward into Kubernetes (and not out from!)
kurun is capable of port forwarding your local application into a Kubernetes cluster using our WebSocket-based tunnel. This is extremely useful for rapid development of Kubernetes admission webhooks for example.
Start a Python SimpleHTTPServer on port 4443 on your machine:
$ python -m SimpleHTTPServer 4443In another terminal session proxy this application into Kubernetes under the Service name python-server:
kurun port-forward --servicename python-server localhost:4443In a third terminal session start up an Alpine Linux image in interactive mode and query the python-server service using curl:
kubectl run alpine --rm --image alpine -it
If you don't see a command prompt, try pressing enter.
/ # apk add curl
fetch http://dl-cdn.alpinelinux.org/alpine/v3.10/main/x86_64/APKINDEX.tar.gz
fetch http://dl-cdn.alpinelinux.org/alpine/v3.10/community/x86_64/APKINDEX.tar.gz
(1/4) Installing ca-certificates (20190108-r0)
(2/4) Installing nghttp2-libs (1.38.0-r0)
(3/4) Installing libcurl (7.65.1-r0)
(4/4) Installing curl (7.65.1-r0)
Executing busybox-1.30.1-r2.trigger
Executing ca-certificates-20190108-r0.trigger
OK: 7 MiB in 18 packages
/ # curl http://python-server
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 3.2 Final//EN"><html>
<title>Directory listing for /</title>
<body>
<h2>Directory listing for /</h2>
<hr>
<ul>
<li><a href=".git/">.git/</a>
<li><a href=".gitignore">.gitignore</a>
<li><a href=".goreleaser.yml">.goreleaser.yml</a>
<li><a href="dist/">dist/</a>
<li><a href="example/">example/</a>
<li><a href="go.mod">go.mod</a>
<li><a href="go.sum">go.sum</a>
<li><a href="kurun">kurun</a>
<li><a href="kurun.go">kurun.go</a>
<li><a href="LICENSE">LICENSE</a>
<li><a href="README.md">README.md</a>
</ul>
<hr>
</body>
</html>It's also possible to proxy HTTPS services from localhost (just add the https:// scheme prefix to the URL):
kurun port-forward --servicename pipeline https://localhost:9090The above will end up as a plaintext service inside Kubernetes.
If you need TLS there as well, you have to provide the TLS type Kubernetes Secret name to kurun:
kubectl create secret tls kurun-cert --cert "tls.crt" --key "tls.key"
kurun port-forward --servicename kurun https://localhost:9090 --tlssecret kurun-certFor more details and examples, please read this post.