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Chat Service NATS JetStream Troubleshooting Summary

This document summarizes the troubleshooting steps taken to resolve issues with the NATS JetStream configuration in the chat service project.

Problem Description

The chat service was encountering errors related to the NATS JetStream configuration, specifically:

  • insufficient storage resources available errors in the ModerationCoordinatorBackgroundService
  • Issues with stream creation and message publishing
  • Port binding conflicts when starting the API service

Troubleshooting Steps in Chronological Order

Initial Investigation

  1. ✅ Checked NATS server status: Verified that the NATS server was running with JetStream enabled using curl -s http://localhost:8222/varz | grep -i jetstream.

  2. ✅ Examined code structure: Analyzed the NatsStream.cs, NatsConfiguration.cs, and other related files to understand how streams are created and configured.

  3. ✅ Reviewed configuration files: Checked appsettings.json and server.conf to understand the current NATS configuration.

Understanding the Issue

  1. ✅ Identified the root cause: The issue was related to JetStream storage configuration. The NatsStream.CreateOrUpdateStream method was creating streams with a size limit based on the MaxBytes configuration (set to 10GB), but the NATS server didn't have enough storage allocated.

  2. ✅ Analyzed error logs: The error logs showed that the ModerationCoordinatorBackgroundService was failing when trying to create streams due to insufficient storage resources.

Solution Implementation

  1. ✅ Updated server.conf: Modified the JetStream configuration in server.conf to use the correct storage directory and set appropriate storage limits:

    jetstream {
   store_dir=/tmp/nats-jetstream/jetstream
   max_memory=1G
   max_file=10G
}

  2. ❌ Attempted to restart NATS with updated config: Tried to restart the NATS server using the updated configuration file, but encountered an error with the max_memory and max_file fields, which were not recognized:

    nats-server: dockerfiles/server.conf:26:4: unknown field "max_memory"

  3. ✅ Created storage directory: Created the /tmp/nats-jetstream/jetstream directory to ensure it exists for NATS to use:

    mkdir -p /tmp/nats-jetstream/jetstream

  4. ✅ Started NATS with explicit parameters: Successfully started the NATS server with explicit command-line parameters:

    nats-server -js -sd /tmp/nats-jetstream/jetstream -m 8222 -user chatservice -pass p@ssw0rd1

  5. ✅ Verified JetStream configuration: Confirmed that JetStream was enabled and properly configured with the correct storage directory using curl -s http://localhost:8222/jsz.

  6. ❌ Attempted to start the API service: Tried to start the API service, but encountered a port binding conflict error because the port was already in use:

    System.IO.IOException: Failed to bind to address http://127.0.0.1:5176: address already in use.

  7. ✅ Checked for running API processes: Verified if there were any running instances of the API service using ps aux | grep "ChatService.API" | grep -v grep.

  8. ❌ Attempted to create a channel: Tried to create a test channel to see if the streams would be created, but still encountered the "insufficient storage resources available" error.

  9. ✅ Checked JetStream streams: Verified the current JetStream streams and their status using curl -s http://localhost:8222/jsz.

Current Status

  • ✅ NATS server is running with JetStream enabled and properly configured
  • ✅ JetStream storage is configured with appropriate limits
  • ❌ API service still encounters the "insufficient storage resources available" error when trying to create streams
  • ❌ Port binding issues when trying to start the API service

Root Cause Analysis

The primary issue is a mismatch between the stream size configuration in the code and the available storage in the NATS server:

  1. In NatsStream.CreateOrUpdateStream, the stream size is calculated as:

    long sizeInBytes = 1024 * 1024;  // 1 MB in bytes
sizeInBytes = sizeInBytes * _natsConfiguration.MaxBytes * 1024; // MaxBytes GB

    With MaxBytes set to 10 in appsettings.json, this results in a 10GB stream size.

  2. The NATS server has a default storage limit that is insufficient for these large streams.

  3. The port binding issue is a separate problem where the API service is trying to use a port that's already in use.

Next Steps

  1. Modify the NatsStream.CreateOrUpdateStream method: Consider reducing the stream size limit in the code or increasing the storage allocation in the NATS server.

  2. Start the API service with a different port: Use the following command to avoid port conflicts:

    cd ChatService.API && ASPNETCORE_URLS=http://localhost:5001 dotnet run

  3. Disable the moderation component temporarily: If the moderation functionality is not critical, consider disabling it temporarily by setting EnableDispatcher to false in the appsettings.json file.

  4. Monitor JetStream usage: Use the NATS monitoring endpoint (http://localhost:8222/jsz) to track JetStream storage usage and ensure it doesn't exceed the allocated limits.

  5. Kill existing API processes: Before starting the API service, ensure there are no existing processes using the required port.

Lessons Learned

  1. JetStream requires explicit storage configuration to handle the volume of messages in the chat service.
  2. The stream size configuration in the code should align with the storage capacity configured in the NATS server.
  3. When troubleshooting NATS issues, checking the JetStream configuration and monitoring endpoints provides valuable insights.
  4. The NATS server configuration file has specific syntax requirements, and not all command-line parameters can be used in the configuration file.
  5. Always check for existing processes that might be using required ports before starting services.