Add week 8 materials

materials/08-scaling/seminar/kv/proxy/main.py

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+import argparse
+import requests
+from strategies import (
+    Proxy, ShardingProxy, 
+    ReplicatingProxy, ReplicatingQuorumProxy,
+    RAID3Proxy
+)
+import yaml
+from flask import Flask, jsonify, request
+
+app = Flask(__name__)
+
+proxy: Proxy = None
+
+
+@app.route('/put', methods=['POST'])
+def put_handler():
+    key = request.args.get('key')
+    value = request.get_json().get('value')
+
+    if key is None or value is None:
+        return jsonify({'error': 'Please provide key and value.'}), 400
+
+    return proxy.put(key, value)
+
+@app.route('/get', methods=['GET'])
+def get_handler():
+    key = request.args.get('key')
+
+    if key is None:
+        return jsonify({'error': 'Please provide key.'}), 400
+
+    return proxy.get(key)
+
+
+@app.route('/state', methods=['GET'])
+def state_handler():
+    results = ""
+    for _, node in proxy.nodes.items():
+        url = f'{node["url"]}/state'
+        response = requests.get(url)
+        results += f'<h1 style="font-family: monospace;">Response from {url}</h1>{response.content.decode("utf-8")}<hr>'
+
+    return f"<html><body>{results}</body></html>", 200
+
+
+def load_proxy_from_config(config_path):
+    with open(config_path, 'r') as file:
+        config = yaml.safe_load(file)
+
+    mode = config.get('mode', '')
+    nodes = {}
+    for node in config['nodes']:
+        name = node['name']
+        url = node['url']
+        nodes[name] = {'url': url}
+    if mode == 'sharding':
+        return ShardingProxy(nodes)
+    elif mode == 'replication':
+        return ReplicatingProxy(nodes)
+    elif mode == 'replication-quorum':
+        return ReplicatingQuorumProxy(nodes)
+    elif mode == 'replication-raid3':
+        return RAID3Proxy(nodes)
+    raise ValueError('Invalid mode, allowed values: sharding, replication, replication-quorum')
+
+
+if __name__ == '__main__':
+    parser = argparse.ArgumentParser(description='Flask app acting as a proxy for key-value nodes')
+    parser.add_argument('-c', '--config', type=str, required=True, help='Path to the YAML config file')
+    parser.add_argument('-p', '--port', type=int, help='Port of the server')
+    args = parser.parse_args()
+
+    proxy = load_proxy_from_config(args.config)
+
+    app.run('0.0.0.0', args.port)