I'm running two Flask apps, one for front-end and one for back-end. I have mapped the front-end to port 8001 and the back-end to port 8002, all runs well when using docker-compose. However, I'm having difficulty transferring my docker images to kubernetes (run locally using minikube). I have read docs and I thought I had mapped my ports correctly, but I'm still receiving an error
Error: 'dial tcp 172.17.0.5:8002: getsockopt: connection refused'
Trying to reach: 'http://172.17.0.5:8002/'
when trying to access the front-end or back-end pods via
http://127.0.0.1:8001/api/v1/namespaces/default/pods/hello-57d6475c59-ghmhs/proxy/
I feel like I'm doing something wrong with the way I'm mapping the ports, but I am not experienced enough with kubernetes to know what. I would appreciate if someone could spot it is I'm missing.
It says both my pods are running.
NAME READY STATUS RESTARTS AGE
frontend-66d5699888-bbbct 1/1 Running 0 48m
hello-57d6475c59-ghmhs 1/1 Running 0 49m
I'm sorry to bombard you with code, but I didn't know how better to convey my effort cohesively. Most of it you can just ignore, it's just for context.
Front-end
from flask import Flask, jsonify
import requests
import json
app = Flask(__name__)
@app.route("/")
def home():
url = "http://backend:5000/"
res = requests.get(url)
dictFromServer = res.json()
return dictFromServer['message']
if __name__=='__main__':
app.run(debug=True, host='0.0.0.0')
Back-end
from flask import Flask, jsonify
app = Flask(__name__)
@app.route('/')
def hello_world():
return jsonify({ 'message': 'Hello World v1 - Demo'})
if __name__=='__main__':
app.run(debug=True, host='0.0.0.0')
Dockerfile (same contents for front & back-end)
FROM python:3.6-alpine
WORKDIR /app
COPY requirement=s.txt /app
COPY app.py /app
RUN pip install -r requirements.txt
EXPOSE 5000
ENTRYPOINT ["python"]
CMD ["app.py"]
frontend.conf
upstream hello {
server hello;
}
server {
listen 8001;
location / {
proxy_pass http://hello;
}
}
frontend.yaml
apiVersion: v1
kind: Service
metadata:
name: frontend
spec:
selector:
app: hello
tier: frontend
ports:
- protocol: "TCP"
port: 8001
targetPort: 8001
type: NodePort
---
apiVersion: apps/v1
kind: Deployment
metadata:
name: frontend
spec:
selector:
matchLabels:
app: hello
tier: frontend
track: stable
replicas: 1
template:
metadata:
labels:
app: hello
tier: frontend
track: stable
spec:
containers:
- name: nginx
image: "jor2/hello-world-kubernetes_frontend"
lifecycle:
preStop:
exec:
command: ["/usr/sbin/nginx","-s","quit"]
hello-service.yaml
kind: Service
apiVersion: v1
metadata:
name: hello
spec:
selector:
app: hello
tier: backend
ports:
- protocol: TCP
port: 8002
targetPort: http
hello.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
name: hello
spec:
selector:
matchLabels:
app: hello
tier: backend
track: stable
replicas: 1
template:
metadata:
labels:
app: hello
tier: backend
track: stable
spec:
containers:
- name: hello
image: "jor2/hello-world-kubernetes_backend"
ports:
- name: http
containerPort: 8002
As stated by jasonlock in his comment, you can use Kompose.
I had previously never heard of Kompose, https://kubernetes.io/docs/tasks/configure-pod-container/translate-compose-kubernetes/, but in one command I could convert it from docker-compose to kubernetes.