Demo: Addressbook

# Webservice ## Webservice itself We use flask as application server (python based). Check if flask is installed/otherwise install it... ```bash sudo apt list python3 python3-venv --installed ``` ```bash sudo apt install python3 python3-venv -y ``` create a folder for the source-code & python dependencies: ```bash sudo mkdir /opt/webservice sudo chown tux:tux /opt/webservice ``` install python dependencies and webservice: ```bash cd /opt/webservice python3 -m venv venv source venv/bin/activate pip install flask flask-restx gunicorn deactivate vi webservice.py ``` and paste following code: ```python from flask import Flask from flask_restx import Api, Resource app = Flask(__name__) api = Api(app) names_list = ["Alice", "Bob", "Charlie"] @api.route('/names') class AddressList(Resource): def get(self): return names_list def post(self): data = api.payload if "name" in data: names_list.append(data["name"]) return {"status": "success"}, 201 api.abort(400) def delete(self): names_list.clear() return {"status": "Liste geleert"}, 200 if __name__ == '__main__': app.run(host='0.0.0.0', port=5000, debug=True) ``` test the webservice: ```bash /opt/webservice/venv/bin/python3 webservice.py ``` Verify the webservice using Postman! URL: `http://:5000/names` ## Reverse-Proxy Stop the webservice simply by pressing `Ctrl + C`, or by `kill `. change the binding of flask to localhost only by modifing the last line of the webservice source-code: ```python if __name__ == '__main__': app.run(host='127.0.0.1', port=5000, debug=True) ``` **Note:** The webservice is no longer accessible from outside the host. Make the webservice available through nginx. ```bash sudo vi /etc/nginx/sites-available/*site-name* ``` add to the server section: ```nginx # API Queries are forwarded to Flask location /api/names { proxy_pass http://127.0.0.1:5000/names; } ``` reload nginx, start the webservice: ```bash sudo systemctl reload nginx /opt/webservice/venv/bin/python3 webservice.py ``` Verify the webservice using Postman! URL: `http://*domain-name*/api/names` The previous URL should **NOT** work anylonger: `http://:5000/names` To start the webservice "production ready", we have a use a wsgi server like gunicorn (which we installed initially via pip): ```bash /opt/webservice/venv/bin/gunicorn -w 1 -b 127.0.0.1:5000 webservice:app ``` ## API Documentation Example | Method | Ressource (Path) | Input (Body) | Datatype (In) | Possible Values | Output (JSON) | Datatype (Out) | Description | | :--- | :--- | :--- | :--- | :--- | :--- | :--- | :--- | | **GET** | `/names` | *n/a* | - | - | `["Alice", "Bob", ...]` | `Array` | returns the complete list of names | | **POST** | `/names` | `{"name": "..."}` | `String` | `*` | `{"status": "success"}` | `String` | adds a new name to the list | | **DELETE** | `/names` | *n/a* | - | - | `{"status": "Liste geleert"}` | `String` | clears the complete list | ## Webapp -> Frontend A simple frontend for the webservice. Create a html document (e.g. `webapp2.html`) with the content: ```html Demo: Addressbook

Einfaches Adressbuch

Einträge:

Liste leeren

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