Monitoring distributed systems is crucial for ensuring their reliability, performance, and security. This topic will cover the key concepts, tools, and techniques used to monitor distributed systems effectively.

1. Observability:

   • Definition: Observability is the ability to measure the internal states of a system by examining its outputs.
   • Components: Metrics, logs, and traces.

2. Metrics:

   • Definition: Quantitative data that measure the performance and health of a system.
   • Examples: CPU usage, memory usage, request rates, error rates, latency.

3. Logs:

   • Definition: Records of events that happen within the system.
   • Examples: Application logs, system logs, security logs.

4. Traces:

   • Definition: Records of the path that a request takes through a distributed system.
   • Examples: Distributed tracing tools like Jaeger and Zipkin.

5. Alerting:

   • Definition: The process of notifying administrators or systems when metrics or logs indicate a problem.
   • Examples: Email alerts, SMS alerts, integration with incident management tools.

1. Prometheus:

   • Description: An open-source systems monitoring and alerting toolkit.
   • Features: Time-series database, powerful query language (PromQL), alerting capabilities.

2. Grafana:

   • Description: An open-source platform for monitoring and observability.
   • Features: Visualization of metrics, integration with various data sources, customizable dashboards.

3. ELK Stack (Elasticsearch, Logstash, Kibana):

   • Description: A set of tools for searching, analyzing, and visualizing log data in real-time.
   • Features: Centralized logging, powerful search capabilities, real-time analytics.

4. Jaeger:

   • Description: An open-source, end-to-end distributed tracing tool.
   • Features: Performance and latency monitoring, root cause analysis, service dependency analysis.

1. Download Prometheus:

   wget https://github.com/prometheus/prometheus/releases/download/v2.26.0/prometheus-2.26.0.linux-amd64.tar.gz
   tar xvfz prometheus-2.26.0.linux-amd64.tar.gz
   cd prometheus-2.26.0.linux-amd64
   

2. Configure Prometheus:

   • Create a prometheus.yml configuration file:

     global:
       scrape_interval: 15s
     
     scrape_configs:
       - job_name: 'prometheus'
         static_configs:
           - targets: ['localhost:9090']
     

3. Start Prometheus:

   ./prometheus --config.file=prometheus.yml
   

1. Download and Install Grafana:

   wget https://dl.grafana.com/oss/release/grafana-7.5.3.linux-amd64.tar.gz
   tar -zxvf grafana-7.5.3.linux-amd64.tar.gz
   cd grafana-7.5.3
   

2. Start Grafana:

   ./bin/grafana-server
   

1. Access Grafana:

   • Open a web browser and navigate to http://localhost:3000.
   • Log in with the default credentials (admin/admin).

2. Add Prometheus Data Source:

   • Go to Configuration -> Data Sources -> Add data source.
   • Select Prometheus.
   • Set the URL to http://localhost:9090 and click Save & Test.

1. Create a New Dashboard:

   • Go to Create -> Dashboard -> Add new panel.

2. Add a Panel:

   • Select a metric from Prometheus (e.g., up).
   • Customize the visualization and save the panel.

1. Set Up a Sample Application:

   • Use a simple web application that exposes Prometheus metrics.
   • Example application: Node Exporter.

2. Configure Prometheus to Scrape the Application:

   • Update prometheus.yml to include the application's metrics endpoint:

     scrape_configs:
       - job_name: 'node_exporter'
         static_configs:
           - targets: ['localhost:9100']
     

3. Create Grafana Dashboards:

   • Create dashboards to visualize the application's metrics (e.g., CPU usage, memory usage).

1. Install Node Exporter:

   wget https://github.com/prometheus/node_exporter/releases/download/v1.1.2/node_exporter-1.1.2.linux-amd64.tar.gz
   tar xvfz node_exporter-1.1.2.linux-amd64.tar.gz
   cd node_exporter-1.1.2.linux-amd64
   ./node_exporter
   

2. Update Prometheus Configuration:

   • Add the following to prometheus.yml:

     scrape_configs:
       - job_name: 'node_exporter'
         static_configs:
           - targets: ['localhost:9100']
     

3. Create Grafana Dashboards:

   • Follow the steps in the practical example to create dashboards for the Node Exporter metrics.

1. Incorrect Prometheus Configuration:

   • Ensure that the prometheus.yml file is correctly formatted and includes all necessary scrape configurations.

2. Grafana Data Source Issues:

   • Verify that the Prometheus data source URL is correct and that Prometheus is running.

3. Alert Fatigue:

   • Avoid setting too many alerts to prevent alert fatigue. Focus on critical metrics that indicate significant issues.

Monitoring distributed systems is essential for maintaining their performance, reliability, and security. By understanding key concepts such as observability, metrics, logs, and traces, and using tools like Prometheus and Grafana, you can effectively monitor and manage distributed systems. Practical exercises help reinforce these concepts and provide hands-on experience with monitoring tools.