http-api

Example application with Docker image, Helm chart and Kubernetes deployment.

Note: Because it's an example project, I won't use WSGI production-ready server to run Flask application. To check available WSGI servers please refer to: https://flask.palletsprojects.com/en/2.0.x/deploying/

Application

The application is created in Flask (python framework). It serves HTTP API endpoint with sample data from https://jsonplaceholder.typicode.com/users.

Requirements: Python3

HTTP endpoints

Get all users data:

/api/v1/users/all

Get user by ID:

/api/v1/users?id=<id>

How to run application

To run application locally, you have to create virtual environment, install requirements and start flask application:

Prepare virtual environment:

cd ./http-api
python3 -m venv venv
. venv/bin/activate
python3 -m pip install -r requirements.txt

Run application locally:

python3 ./http-api/app.py

Docker image

You can easly build application in docker by typing the following command:

docker build --tag http-api:latest .

The image is also available on Dockerhub:

docker pull rafzei/http-api:latest

To run an application in Docker, execute:

docker run -ti --name http-api http-api:latest

Monitoring

In addition, you could use provided docker-compose file. It contains Prometheus and Grafana image definitions. In ./configs directory you can find config files for both, as well as Grafana dashboard.

To run monitoring tools along with application, execute:

docker-compose up --build

The Flask application exposes its metrics on /metrics endpoint. Example:

http://<url>:5000/metrics

To reach provided Grafana dashboard:

http://<url>:3000/d/app/flask-app

To get Prometheus GUI:

http://<url>:9090/graph

As <url> you could use localhost or container ip address (check it via docker inspect).

Helm

Helm chart

To run a chart execute the following command:

helm helm upgrade --install http-api --namespace http-api --create-namespace ./charts/http-api/

Note: To be able to run ingress on minikube, make sure your minikube is in the latest released version and enable addon:

minikube addons enable ingress

For details see the official documentation

Helm hook

I've provided sample Helm hook (job) which can be adjusted and used for migrations between releases. See here

Helm test

Please, refer to: docs/tests

Kubernetes

Because the yaml's are already in the Helm charts, you could use it as source of true and generate manifests needed for example by kubectl. Execute the following command:

helm template http-api ./charts/http-api/ --namespace http-api --create-namespace --output-dir ./kubernetes --no-hooks --skip-tests

Because the namespace is created during helm chart execution, you have to provide it mannualy before kubectl apply -f <file.yml> execution.

Example:

kubectl create namespace http-api

Open-policy-agent (OPA)

This part assumes, that you already have OPA user, namespace and rbac created (TODO: Implement in v0.2.0).

Files related to OPA are included in opa dir:

• deployment.yaml - deploys OPA in a cluster
• check-container-user.rego - provice policy file to check if user is not privileged
• service.yaml - provide clusterIP service for ingress
• ingress.yaml - provide ingress to reach OPA API

To apply OPA execute the following commands:

kubectl create configmap check-container-user --from-file ./opa/check-container-user.rego
kubectl apply -f ./opa/deployment.yaml
kubectl apply -f ./opa/service.yaml
kubectl apply -f ./opa/ingress.yaml