Continuing this short series of writing a simple echo service web API along with the docker and k8s requirements, we’re now going to turn our attention to a Python implementation.<\/p>\n
Implementation<\/strong><\/p>\n I’m using JetBrains PyCharm for this project, so I created a project named echo_service<\/em>.<\/p>\n Next, add the file app.py with the following code<\/p>\n Add a requirements.txt file with the following<\/p>\n Don’t forget to install the packages via the IDE.<\/p>\n Dockerfile<\/strong><\/p>\n Next up we need to create our Dockerfile<\/p>\n Note: we’ll be using gunicorn <\/em> instead of the development server.<\/p>\n Note: In Linux port 80 might be locked down, hence we use port 8080 by default.<\/em><\/p>\n To build this, run <\/p>\n Don’t forget to change the name to your preferred name.<\/em><\/p>\n and to test this, run<\/p>\n Kubernetes<\/strong><\/p>\n If all wen well we’ve not tested our application and see it working from a docker image, so now we need to create the deployment etc. for Kubernete’s. Let’s assume you’ve pushed you image to Docker or another container registry such as Azure – I’m call my container registry putridparrotreg<\/em>.<\/p>\n I’m also not going to use helm at this point as I just want a (relatively) simple yaml file to run from kubectl, so create a deployment.yaml file, we’ll store all the configurations, deployment, service and ingress in this one file jus for simplicity.<\/p>\n\r\nfrom flask import Flask, request\r\n\r\napp = Flask(__name__)\r\n\r\n@app.route('\/echo')\r\ndef echo():\r\n text = request.args.get('text', '')\r\n return f"Python Echo: {text}", 200\r\n\r\n@app.route('\/livez')\r\ndef livez():\r\n return "OK", 200\r\n\r\n@app.route('\/readyz')\r\ndef readyz():\r\n return "Ready", 200\r\n\r\nif __name__ == '__main__':\r\n app.run(host='0.0.0.0', port=8080)\r\n<\/pre>\n\r\nflask\r\ngunicorn\r\n<\/pre>\n
\r\n# Use a lightweight Python base\r\nFROM python:3.11-slim\r\n\r\nWORKDIR \/app\r\n\r\nCOPY requirements.txt .\r\nRUN pip install --no-cache-dir -r requirements.txt\r\n\r\nCOPY app.py .\r\n\r\nCMD ["gunicorn", "-w", "2", "-b", "0.0.0.0:8080", "app:app"]\r\n<\/pre>\n
\r\ndocker build -t putridparrot.echo_service:v1 .\r\n<\/pre>\n
\r\ndocker run -p 8080:8080 putridparrot.echo_service:v1\r\n<\/pre>\n
\r\napiVersion: apps\/v1\r\nkind: Deployment\r\nmetadata:\r\n name: echo\r\n namespace: dev\r\n labels:\r\n app: echo\r\nspec:\r\n replicas: 1\r\n selector:\r\n matchLabels:\r\n app: echo\r\n template:\r\n metadata:\r\n labels:\r\n app: echo\r\n spec:\r\n containers:\r\n - name: echo\r\n image: putridparrotreg\/putridparrot.echo_service:v1\r\n ports:\r\n - containerPort: 8080\r\n resources:\r\n requests:\r\n memory: "100Mi"\r\n cpu: "100m"\r\n limits:\r\n memory: "200Mi"\r\n cpu: "200m"\r\n livenessProbe:\r\n httpGet:\r\n path: \/livez\r\n port: 8080\r\n initialDelaySeconds: 30\r\n periodSeconds: 10\r\n readinessProbe:\r\n httpGet:\r\n path: \/readyz\r\n port: 8080\r\n initialDelaySeconds: 5\r\n periodSeconds: 5\r\n\r\n---\r\napiVersion: v1\r\nkind: Service\r\nmetadata:\r\n name: echo_service\r\n namespace: dev\r\n labels:\r\n app: echo\r\nspec:\r\n type: ClusterIP\r\n selector:\r\n app: echo \r\n ports:\r\n - name: http\r\n port: 80\r\n targetPort: 8080\r\n protocol: TCP\r\n---\r\napiVersion: networking.k8s.io\/v1\r\nkind: Ingress\r\nmetadata:\r\n name: echo-ingress\r\n namespace: dev\r\n annotations:\r\n kubernetes.io\/ingress.class: "nginx"\r\n nginx.ingress.kubernetes.io\/rewrite-target: \/\r\nspec:\r\n rules:\r\n - host: mydomain.com\r\n http:\r\n paths:\r\n - path: \/\r\n pathType: Prefix\r\n backend:\r\n service:\r\n name: echo_service\r\n port:\r\n number: 80\r\n<\/pre>\n