registry service

Author: reukiodo

.gitignore

@@ -0,0 +1 @@
+venv/

files/service_registry.service

@@ -0,0 +1,16 @@
+[Unit]
+Description=Dragon Cafe Service Registry
+
+[Service]
+User=root
+Group=root
+
+WorkingDirectory=/home/student/dragon-cafe
+ExecStart=/home/student/dragon-cafe/venv/bin/python3 service_registry.py
+
+StandardOutput=syslog
+StandardError=syslog
+SyslogIdentifier=dragon-cafe-sr
+
+[Install]
+WantedBy=multi-user.target

requirements.txt

@@ -3,3 +3,4 @@ jinja2==3.0.1
 beautifulsoup4==4.9.3
 bs4==0.0.1
 requests==2.25.1
+aiosqlite==0.17.0

service_registry.db

@@ -0,0 +1,117 @@
+#!/usr/bin/env python3
+
+from aiohttp import web
+import os
+import aiosqlite
+import datetime
+import random
+import subprocess
+import jinja2
+import pwd
+import grp
+
+PORT = os.getenv("SR_PORT", 55555)
+HOST = os.getenv("SR_HOST", "0.0.0.0")
+DB_NAME = os.getenv("SR_DB_NAME", "service_registry.db")
+
+
+def routes(app: web.Application) -> None:
+    app.add_routes(
+        [
+            web.get("/add/{service}/{ip}/{port}", add_service),
+            web.get("/remove/{service}/{ip}/{port}", remove_service),
+            web.get("/heartbeat/{service}/{ip}/{port}", heartbeat),
+            web.get("/get/{service}", get_service),
+            web.get("/get_one/{service}", get_one_service)
+        ]
+    )
+    return None
+
+
+async def add_service(request):
+    service = request.match_info.get('service')
+    ip = request.match_info.get('ip')
+    port = request.match_info.get('port')
+    print(f"Adding the {service} service")
+    async with aiosqlite.connect(DB_NAME) as db:
+        sql = f"CREATE TABLE IF NOT EXISTS {service} (ip CHAR(16), port INT, heartbeat CHAR(50), alive  BOOL);"
+        await db.execute(sql)
+        await db.commit()
+        now = datetime.datetime.now()
+        sql2 = f"INSERT INTO {service} (ip, port, heartbeat, alive) VALUES ('{ip}', '{port}', '{now}', 'TRUE');"
+        try:
+            await db.execute(sql2)
+            await db.commit()
+            txt = ""
+        except aiosqlite.IntegrityError as err:
+            txt = f"{service} service already exists"
+    return web.Response(text=txt)
+
+
+async def heartbeat(request):
+    service = request.match_info.get('service')
+    ip = request.match_info.get('ip')
+    port = request.match_info.get('port')
+    print(f"Adding heartbeat")
+    async with aiosqlite.connect(DB_NAME) as db:
+        now = datetime.datetime.now()
+        sql = f"UPDATE {service} set heartbeat = '{now}' where ip like '{ip}' AND port like '{port}';"
+        await db.execute(sql)
+        await db.commit()
+    return web.Response()
+
+
+async def remove_service(request):
+    service = request.match_info.get('service')
+    ip = request.match_info.get('ip')
+    port = request.match_info.get('port')
+    print(f"Removing {ip} from the {service} service")
+    async with aiosqlite.connect(DB_NAME) as db:
+        now = datetime.datetime.now()
+        sql = f"UPDATE {service} set heartbeat = '{now}', alive = 'FALSE' where ip like '{ip}' AND port like '{port}';"
+        print(sql)
+        await db.execute(sql)
+        await db.commit()
+    return web.Response()
+
+
+async def get_service(request):
+    service = request.match_info.get('service')
+    async with aiosqlite.connect(DB_NAME) as db:
+        sql = f"SELECT DISTINCT ip,port from {service} where alive = 'TRUE';"
+        resp = await db.execute(sql)
+        await db.commit()
+        fetched = await resp.fetchall()
+        services = {'endpoints': fetched}
+    return web.json_response(services)
+
+
+async def get_one_service(request):
+    service = request.match_info.get('service')
+    async with aiosqlite.connect(DB_NAME) as db:
+        sql = f"SELECT ip,port from {service} where alive = 'TRUE';"
+        resp = await db.execute(sql)
+        await db.commit()
+        fetched = await resp.fetchall()
+    chosen = random.choice(fetched)
+    services = {'endpoints': chosen}
+    return web.json_response(services)
+
+
+def main():
+    """
+    This is the main process for the aiohttp server.
+    This works by instantiating the app as a web.Application(),
+    then applying the setup function we built in our routes
+    function to add routes to our app, then by starting the async
+    event loop with web.run_app().
+    """
+
+    print("This aiohttp web server is starting up!")
+    app = web.Application()
+    routes(app)
+    web.run_app(app, host=HOST, port=PORT)
+
+
+if __name__ == "__main__":
+    main()