Getting started with Gefyra and k3d

This guide will show you how to use Gefyra for the local development of a Kubernetes application running in k3d.

Prerequisites

Hint there is a bug in Docker Desktop v4.17-v4.18 which causes gefyra up to fail with k3d clusters that run on that DD version.

Create a local Kubernetes cluster with k3d like so:
< v5

k3d cluster create mycluster --agents 1 -p 8080:80@agent[0] -p 31820:31820/UDP@agent[0]

>= v5

k3d cluster create mycluster --agents 1 -p 8080:80@agent:0 -p 31820:31820/UDP@agent:0

This creates a Kubernetes cluster that binds port 8080 and 31820 to localhost. kubectl context is immediately set to this cluster.

Apply some workload, for example from the testing directory of this repo:
```
kubectl apply -f https://raw.githubusercontent.com/gefyrahq/gefyra/main/testing/workloads/hello.yaml
```
Check out this workload running under: http://hello.127.0.0.1.nip.io:8080/

Set up Gefyra with
```
gefyra up
```
Run a local Docker image with Gefyra in order to make it part of the cluster.
1. Build your Docker image with a local tag, for example from the testing directory: cd testing/images/ && docker build -f Dockerfile.local . -t pyserver
2. Execute Gefyra’s run command:
```
gefyra run -i pyserver -N mypyserver -n default
```
3. Exec into the running container and look around. You will find the container to run within your Kubernetes cluster.
```
docker exec -it mypyserver bash
```
```
wget -O- hello-nginx
```
  will print out the website of the cluster service hello-nginx from within the cluster.
Create a bridge in order to intercept the traffic to the cluster application with the one running locally:
```
gefyra bridge -N mypyserver -n default --port 8000:80 --target deploy/hello-nginxdemo/hello-nginx
```
Check out the locally running server comes up under: http://hello.127.0.0.1.nip.io:8080/
List all running bridges:
```
gefyra list --bridges
```
Unbridge the local container and reset the cluster to its original state:
```
gefyra unbridge -N mypybridge
```
Check out the initial response from: http://hello.127.0.0.1.nip.io:8080/

Remove Gefyra’s components from the cluster with
```
gefyra down
```
Remove the locally running Kubernetes cluster with
```
k3d cluster delete mycluster
```