In this post I am going to describe how I deployed my python service on kubernetes and how I realized connection to external database.

About application

The test application is based on FastAPI module. Main purpose of the service is handling incomming requests and save them into the databse. For database system I used Postgres.

Connection values and other variables were defined in .env file located in application running folder.

Deploy application

First of all it was created a namespace:

kubectl create namespace newsbase

Then, deployed a secret file for pulling an image for the images registry. auth.json file I found in /run/user/1000/containers/auth.json of the machine where the image registry is runnning:

kubectl create secret generic regcred --from-file=.dockerconfigjson=../auth.json --type=kubernetes.io/dockerconfigjson -n newsbase

Next, prepare deployment.yml file and apply it afterwards:

Content of deployment.yml file:


---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: newsbase
  namespace: newsbase
spec:
  selector:
    matchLabels:
      app: newsbase
      tier: newsbase
      track: stable
  replicas: 3
  template:
    metadata:
      labels:
        app: newsbase
        track: stable
    spec:
      containers:
        - name: newsbase
          image: "registry.ocp.home.lab:5000/newsbase:1.0"
          ports:
            - name: newsbase
              containerPort: 9080
              protocol: TCP
      imagePullSecrets:
        - name: regcred

This deployment.yml file describes following:

  • application and namespace name is newsbase;
  • it will be running 3 pods: replicas: 3
  • image will be deployed from the registry.ocp.home.lab:5000/newsbase:1.0
  • port 9080 will be exposed
  • secret named regcred will be to access to the image registry;

And apply deployment.yml file:

[admin@workstation newsbase]$ kubectl apply -f deployment.yml 
deployment.apps/newsbase created

Check if pods have been running:

[admin@workstation newsbase]$ kubectl get pods -n newsbase
NAME                        READY   STATUS    RESTARTS   AGE
newsbase-7c4bb87566-ghmv8   1/1     Running   1          5m
newsbase-7c4bb87566-jqnnr   1/1     Running   1          5m
newsbase-7c4bb87566-pqw68   1/1     Running   1          5m
[admin@workstation newsbase]$

Activate service for application

In order to access to the application I created service resource.

Content of the service.yml is following:

apiVersion: v1
kind: Service
metadata:
  name: newsbase
  namespace: newsbase
spec:
  ports:
    - port: 9080
      nodePort: 30080
  selector:
    app: newsbase
  type: NodePort

To apply a service run the similar command with apply argument:

kubectl apply -f service.yml

Apply endpoint resource

Endpoint I need configure connection to external database. Here is the yaml file of the resource


---
kind: Service
apiVersion: v1
metadata:
  name: connection-to-db
  namespace: newsbase
spec:
  clusterIP: None
  ports:
  - port: 5432

---
kind: Endpoints
apiVersion: v1
metadata:
  name: connection-to-db
  namespace: newsbase
subsets:
  - addresses:
        - ip: 192.168.11.62
    ports:
      - port: 5432
        name: connection-to-db

References

You may also enjoy