Building a Server Monitoring and Notification System

Setup

• Before running:

  1. (Optional) Change values of the environment variables in example.env.
  2. (Optional) Override appsettings.json variables in example.env.
  3. Rename example.env to .env.

• How to run:

  1. Simply run docker compose.

Main Tasks

Task 1: Server Statistics Collection Service

• Objective: Develop a C# process that collects and publishes server statistics, specifically memory usage, available memory, and CPU usage.
• Requirements:
  • Collect server statistics (memory usage, available memory, and CPU usage) at regular intervals, specified by a configurable period SamplingIntervalSeconds, using the System.Diagnostics namespace.
  • Encapsulate the collected statistics (memory usage, available memory, CPU usage, and timestamp) into a statistics object.
  • Publish the statistics object to a message queue under the topic ServerStatistics.<ServerIdentifier>, where <ServerIdentifier> is a configurable option.
  • Implement an abstraction for message queuing to ensure the code is not tightly coupled to RabbitMQ.

Code Snippet: Server Statistics Data Type (Class Definition)

// Define a class for server statistics
public class ServerStatistics
{
    public double MemoryUsage { get; set; } // in MB
    public double AvailableMemory { get; set; } // in MB
    public double CpuUsage { get; set; }
    public DateTime Timestamp { get; set; }
}

Code Snippet: Server Statistics Configuration (appsettings.json)

// Configuration options in appsettings.json
{
  "ServerStatisticsConfig": {
    "SamplingIntervalSeconds": 60,
    "ServerIdentifier": "linux1"
  }
}

Task 2: Message Processing and Anomaly Detection Service

• Objective: Develop a C# process that receives server statistics from the message queue, persists the data to a MongoDB instance, and sends alerts if anomalies or high usage is detected.
• Requirements:
  • Receive messages from the message queue with the topic ServerStatistics.* and deserialize them into objects containing memory usage, available memory, CPU usage, server's identifier, and timestamp.
  • Persist the deserialized data to a MongoDB instance.
  • Implement anomaly detection logic based on configurable threshold percentages specified in appsettings.json.
  • Send an "Anomaly Alert" via SignalR if a sudden increase (anomaly) in memory usage or CPU usage is detected.
  • Send a "High Usage Alert" via SignalR if the calculated memory usage percentage or CPU usage exceeds the specified "Usage Threshold".
  • Implement abstractions for MongoDB and message queuing to ensure the code is not tightly coupled to specific implementations.

Equations for Alert Calculation:

• For Anomaly Alert:
  • Memory Usage Anomaly Alert: if (CurrentMemoryUsage > (PreviousMemoryUsage * (1 + MemoryUsageAnomalyThresholdPercentage)))
  • CPU Usage Anomaly Alert: if (CurrentCpuUsage > (PreviousCpuUsage * (1 + CpuUsageAnomalyThresholdPercentage)))
• For High Usage Alert:
  • Memory High Usage Alert: if ((CurrentMemoryUsage / (CurrentMemoryUsage + CurrentAvailableMemory)) > MemoryUsageThresholdPercentage)
  • CPU High Usage Alert: if (CurrentCpuUsage > CpuUsageThresholdPercentage)

Code Snippet: Server Statistics Data Type (Class Definition)

// Define a class for server statistics
public class ServerStatistics
{
    public String ServerIdentifier { get; set; }
    public double MemoryUsage { get; set; } // in MB
    public double AvailableMemory { get; set; } // in MB
    public double CpuUsage { get; set; }
		public DateTime Timestamp { get; set; }
}

Code Snippet: Anomaly Detection Service Configuration (appsettings.json)

// Configuration options in appsettings.json
{
  "AnomalyDetectionConfig": {
    "MemoryUsageAnomalyThresholdPercentage": 0.4,
    "CpuUsageAnomalyThresholdPercentage": 0.5,
    "MemoryUsageThresholdPercentage": 0.8,
    "CpuUsageThresholdPercentage": 0.9
  },
  "SignalRConfig": {
    "SignalRUrl": "<http://your-signalr-hub-url>"
  }
}

Task 3: SignalR Event Consumer Service

• Objective: Develop a C# process that connects to a SignalR hub and prints received events to the console.
• Requirements:
  • Establish a connection to a SignalR hub.
  • Subscribe to events and print them to the console as they are received.

Code Snippet: SignalR Event Consumer Service Configuration (appsettings.json)

// Configuration options in appsettings.json
{
  "SignalRConfig": {
    "SignalRUrl": "<http://your-signalr-hub-url>"
  }
}

Optional Tasks:

Optional Task 4: Create a Reusable RabbitMQ Client Library

• Objective: Develop a reusable class library for interacting with RabbitMQ, thereby abstracting the RabbitMQ client and making it easier to switch to a different message queuing system in the future.
• Requirements:
  • Implement a class for publishing messages to a RabbitMQ exchange.
  • Implement a class for consuming messages from a RabbitMQ queue.
  • Both classes should utilize an interface, making the library extensible and not tightly coupled to RabbitMQ.

Optional Task 5: Dockerization of Services

• Objective: Dockerize the services to enable containerized deployments.
• Requirements:
  • Modify the services to accept configuration options through environment variables instead of appsettings.json.
  • Ensure that all components (Server Statistics Collection Service, Message Processing and Anomaly Detection Service, and SignalR Event Consumer Service) are running and integrated correctly within Docker containers.

Optional Task 6: Docker Compose Integration

• Objective: Use Docker Compose to orchestrate the deployment of the entire system.
• Requirements:
  • Create a Docker Compose file that defines the services, their dependencies, and their configurations.
  • Deploy the entire system, including RabbitMQ and MongoDB instances, using Docker Compose.

Note: It’s possible to create multiple versions of the same image using tags. Here, for example, we build two different versions of the image; one of them is intended to run on a Linux environment, and the other is intended to run on a Windows environment. We distinguish them with the image tag (i.e., image:tag).