Issues connecting with MongoDB

Question

My application from ECS was connecting fine to MongoDB and recently we started encoutering issues with MongoDB connection. I have attached logs for your reference. Tried everything and running out of options.

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app listening on port 3000
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(node:40) NOTE: The AWS SDK for JavaScript (v2) is in maintenance mode.
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SDK releases are limited to address critical bug fixes and security issues only.
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Please migrate your code to use AWS SDK for JavaScript (v3).
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For more information, check the blog post at https://a.co/cUPnyil
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(Use `node --trace-warnings ...` to show where the warning was created)
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/user/node_modules/mongodb/lib/cmap/connect.js:387
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return new error_1.MongoNetworkError(err);
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^
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MongoNetworkError: Client network socket disconnected before secure TLS connection was established
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at connectionFailureError (/user/node_modules/mongodb/lib/cmap/connect.js:387:20)
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at TLSSocket. (/user/node_modules/mongodb/lib/cmap/connect.js:310:22)
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at Object.onceWrapper (node:events:639:26)
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at TLSSocket.emit (node:events:524:28)
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at TLSSocket.emit (node:domain:489:12)
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at emitErrorNT (node:internal/streams/destroy:169:8)
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at emitErrorCloseNT (node:internal/streams/destroy:128:3)
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at process.processTicksAndRejections (node:internal/process/task_queues:82:21) {
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cause: Error: Client network socket disconnected before secure TLS connection was established
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at TLSSocket.onConnectEnd (node:_tls_wrap:1730:19)
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at TLSSocket.emit (node:events:536:35)
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at TLSSocket.emit (node:domain:489:12)
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at endReadableNT (node:internal/streams/readable:1698:12)
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at process.processTicksAndRejections (node:internal/process/task_queues:82:21) {
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code: 'ECONNRESET',
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path: undefined,
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host: 'ac-4dtjvxt-shard-00-02.hcr3a.mongodb.net',
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port: 27017,
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localAddress: undefined
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},
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connectionGeneration: 0,
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[Symbol(errorLabels)]: Set(1) { 'ResetPool' }
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}
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Node.js v20.19.5
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[31m[nodemon] app crashed - waiting for file changes before starting...[39m

Naeem · Answer

Thanks for the suggestions. I checked all the above points most of it is validated except for point 6. So I think the issue is with DNS resolution. When checked from within the ECS task using 
curl -v https://stagedatabase.*******6au.mongodb.net → I get "Could not resolve host"
and ping also reports “Name or service not known”.

re:Post Agent · Answer

Based on your logs, you're experiencing a MongoDB connection issue from your ECS container with the error "MongoNetworkError: Client network socket disconnected before secure TLS connection was established" and "ECONNRESET". This indicates a network connectivity problem between your ECS container and the MongoDB Atlas cluster.

Here are several potential causes and solutions:

1. Network Configuration Issues:
- Check if your ECS container is running in a private subnet. If so, ensure you have a properly configured NAT Gateway in a public subnet to route outbound traffic to the internet.
- Verify that the route tables for your private subnets include a route to the NAT Gateway for internet-bound traffic (0.0.0.0/0).

2. Security Group Configuration:
- Ensure your security group allows outbound traffic to all destinations (0.0.0.0/0) on the necessary ports. MongoDB Atlas typically requires outbound access on ports 27015-27017.
- Double-check that any inbound rules are properly configured if needed.

3. MongoDB Atlas Whitelist:
- Verify that the IP address of your NAT Gateway (if using one) or your ECS environment's public IP is whitelisted in MongoDB Atlas.
- You could temporarily whitelist all IPs (0.0.0.0/0) for testing purposes.

4. TLS Configuration:
- The error specifically mentions a TLS connection issue. Ensure you're using the correct CA certificate and that TLS is properly configured in your connection string.
- For MongoDB Atlas, make sure your connection string includes the necessary TLS options.

5. Connection String:
- Double-check that you're using the correct MongoDB Atlas connection string format in your application's environment variables.
- The format should be something like: mongodb+srv://username:password@cluster.mongodb.net/dbname

6. DNS Resolution:
- Ensure that your ECS environment can resolve the DNS name of the MongoDB Atlas cluster.

7. Network ACLs:
- Check if there are any Network ACLs in your VPC that might be blocking outbound traffic to MongoDB Atlas.

Since this was working previously and recently started failing, consider what changes might have occurred:
- Has your MongoDB Atlas configuration changed?
- Have there been any recent updates to your VPC, security groups, or network settings?
- Has your application code or connection string been modified?

To further diagnose the issue, you could enable VPC Flow Logs to analyze the network traffic and identify any potential blockages.  
**Sources**  
[Connection Error With MongoDB Atlas Via ECS | AWS re:Post](https://repost.aws/questions/QUOkcQqxI0T-GNu9Rd54cxIA/connection-error-with-mongodb-atlas-via-ecs)  
[Next.js App Deployed with Elastic Beanstalk Unable to Connect to MongoDB Atlas | AWS re:Post](https://repost.aws/questions/QUd4YPN40jSpOerD5xWGPTNw/next-js-app-deployed-with-elastic-beanstalk-unable-to-connect-to-mongodb-atlas)

Issues connecting with MongoDB

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