fix: not crash when can't connect to mongoshake url (#7)

README.md

@@ -35,8 +35,8 @@ More information about the metrics that Alibaba MongoShake exports on its endpoi
 
 To use the MongoShake Prometheus Exporter, attention must be paid to two mandatory environment variables:
 
-- `URL_LIST`: A list of URLs to be queried by the MongoShake Prometheus Exporter including the access port and path.
-- `SCRAPE_INTERVAL`: The time interval at which the MongoShake Prometheus Exporter will query the URLs.
+- `MONGOSHAKE_SCRAPE_URL`: A list of URLs to be queried by the MongoShake Prometheus Exporter including the access port and path.
+- `MONGOSHAKE_SCRAPE_INTERVAL`: The time interval at which the MongoShake Prometheus Exporter will query the URLs.
 
 ### Example
 
@@ -97,7 +97,7 @@ docker pull ghcr.io/osgurisdosre/mongoshake-prometheus-exporter:main
 
 Run:
 ```bash
-docker run -p 8000:8000 -p 9100:9100 -p 9200:9200 -e SCRAPE_INTERVAL="5" -e URL_LIST="http://host.docker.internal:9100/repl,http://host.docker.internal:9200/repl" ghcr.io/osgurisdosre/mongoshake-prometheus-exporter:main
+docker run -p 8000:8000 -p 9100:9100 -p 9200:9200 -e MONGOSHAKE_SCRAPE_INTERVAL="5" -e MONGOSHAKE_SCRAPE_URL="http://host.docker.internal:9100/repl,http://host.docker.internal:9200/repl" ghcr.io/osgurisdosre/mongoshake-prometheus-exporter:main
 ```
 
 In the command above, we are exporting ports `9100` and `9200` to the container in addition to port `8000` from the container to the host. In this case, as we want the container to interpret the `URL` locallhost from the host and not the container, we use the following host.docker.internal.

src/app.py

@@ -11,9 +11,9 @@
 prometheus_client.REGISTRY.unregister(prometheus_client.GC_COLLECTOR)
 
 # List of URLs to scrape
-URL_LIST=os.environ["URL_LIST"].split(",")
+MONGOSHAKE_SCRAPE_URL=os.environ.get("MONGOSHAKE_SCRAPE_URL", "http://localhost:9100/repl").split(',')
 # Scrape interval
-SCRAPE_INTERVAL=int(os.environ["SCRAPE_INTERVAL"])
+MONGOSHAKE_SCRAPE_INTERVAL=int(os.environ.get("MONGOSHAKE_SCRAPE_INTERVAL", 10))
 
 # Prometheus metric names
 metric_prefix = "mongoshake"
@@ -27,13 +27,16 @@
 
 # Fetch url data
 async def fetch_metrics(url, prom_metrics):
-    async with aiohttp.ClientSession() as session:
-        async with session.get(url, headers={"Accept": "application/json"}) as response:
-            if response.status == 200:
-                data = await response.json(content_type=None)
-                update_prometheus_metrics(data, prom_metrics, url)
-            else:
-                print(f"Failed to fetch data from {url}: {response.status}")
+    try:
+        async with aiohttp.ClientSession() as session:
+            async with session.get(url, headers={"Accept": "application/json"}) as response:
+                if response.status == 200:
+                    data = await response.json(content_type=None)
+                    update_prometheus_metrics(data, prom_metrics, url)
+                else:
+                    print(f"Failed to fetch data from {url}: {response.status}")
+    except Exception as err:
+        print(err, url)
 
 # Print metrics in webserver 
 def update_prometheus_metrics(data, prom_metrics, url):
@@ -55,10 +58,10 @@ async def main():
 
     # Start app
     while True:
-        await asyncio.gather(*[fetch_metrics(url, prom_metrics) for url in URL_LIST])
+        await asyncio.gather(*[fetch_metrics(url, prom_metrics) for url in MONGOSHAKE_SCRAPE_URL])
 
         # Wait for 5 scrape interval
-        await asyncio.sleep(SCRAPE_INTERVAL)
+        await asyncio.sleep(MONGOSHAKE_SCRAPE_INTERVAL)
 
 if __name__ == "__main__":
     try: