Getting started with Gefyra and Colima Kubernetes
This guide will show you how to use Gefyra for the local development of a Kubernetes application running in Colima Kubernetes.
Prerequisites
Creating a local Kubernetes cluster
1. Creating a local Kubernetes cluster with colima
colima start --kubernetes --network-address
2. Find out the network address of your VM:
colima list
PROFILE STATUS ARCH CPUS MEMORY DISK RUNTIME ADDRESS
default Running x86_64 2 2GiB 60GiB docker+k3s 192.168.106.2
3. 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
4. Check the output of the deployed app with:
kubectl expose deployment hello-nginxdemo --type=LoadBalancer --port=80
Check out this workload running under: http://hello.127.0.0.1.nip.io/
Running Gefyra
1. Set up Gefyra with your Colima cluster:
gefyra up
Important:
2. Run a local Docker container with Gefyra in order to connect it with the cluster.
2.1 Build a simple Docker image with a local tag. Save the following two files in a directory on your disk.
File ./Dockerfile
FROM ubuntu
# run a server on port 8000
RUN apt update && apt install -y iproute2 iputils-ping python3 traceroute wget curl
COPY local.py local.py
CMD python3 local.py
File ./local.py
import http.server
import signal
import socket
import socketserver
import sys
from datetime import datetime
if sys.argv[1:]:
port = int(sys.argv[1])
else:
port = 8000
class MyHttpRequestHandler(http.server.SimpleHTTPRequestHandler):
def do_GET(self):
self.send_response(200)
self.send_header("Content-type", "text/html")
self.end_headers()
hostname = socket.gethostname()
now = datetime.utcnow()
self.wfile.write(
bytes(
f"<html><body><h1>Hello from Gefyra. It is {now} on"
f" {hostname}.</h1></body></html>".encode("utf-8")
)
)
my_handler = MyHttpRequestHandler
server = socketserver.ThreadingTCPServer(("", port), my_handler)
def signal_handler(signal, frame):
try:
if server:
server.server_close()
finally:
sys.exit(0)
signal.signal(signal.SIGINT, signal_handler)
try:
while True:
sys.stdout.flush()
server.serve_forever()
except KeyboardInterrupt:
pass
server.server_close()
2.2 Build it by running docker build -f Dockerfile . -t pyserver in your directory.
2.3 Execute Gefyra's run command:
gefyra run -d -i pyserver -N mypyserver -n default
Important: gefyra run is just a wrapper for docker run (with additional flags), yet it also applies Gefyra's networking
configuration to connect the container with Kubernetes. Check out the docs for gefyra run
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. 🚀
4. Create a bridge to redirect the traffic from the cluster application to the one running locally:
gefyra bridge -N mypyserver -n default --ports 80:8000 --target deploy/hello-nginxdemo/hello-nginx
Check out the locally running server serving the cluster by refreshing the address from the service in Kubernetes.
It shows you a different message: Hello from Gefyra. It is .... Yes, that is really coming from your local container! 😎
5. List all running bridges:
You can list all currently active bridges with:
gefyra list --bridges
You will find all local containers that are currently linked into the cluster serving requests.
6. Unbridge the local container and reset the cluster to its original state:
gefyra unbridge --all
Check out the original response from from the service. The cluster is now reset to its inital state again.
Cleaning up
Remove Gefyra's components from the cluster and your local Docker host with:
gefyra down
- Remove the locally running Kubernetes cluster with
colima delete
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