cAdvisor: Container Resource Metrics

cAdvisor (Container Advisor) provides container-level resource usage and performance metrics. Developed by Google, it auto-discovers running containers and collects CPU, memory, network, and filesystem metrics — essential data for monitoring Docker and Kubernetes environments. This guide covers deploying cAdvisor and integrating with Prometheus and Grafana.

Deployment

# Docker (recommended)
docker run -d --name cadvisor \
    --volume=/:/rootfs:ro \
    --volume=/var/run:/var/run:ro \
    --volume=/sys:/sys:ro \
    --volume=/var/lib/docker/:/var/lib/docker:ro \
    --volume=/dev/disk/:/dev/disk:ro \
    --privileged \
    --device=/dev/kmsg \
    -p 8080:8080 \
    gcr.io/cadvisor/cadvisor:v0.49.1

# Access web UI at http://localhost:8080
# Prometheus metrics at http://localhost:8080/metrics

Docker Compose

services:
  cadvisor:
    image: gcr.io/cadvisor/cadvisor:v0.49.1
    container_name: cadvisor
    privileged: true
    devices:
      - /dev/kmsg:/dev/kmsg
    volumes:
      - /:/rootfs:ro
      - /var/run:/var/run:ro
      - /sys:/sys:ro
      - /var/lib/docker/:/var/lib/docker:ro
      - /dev/disk/:/dev/disk:ro
    ports:
      - "8080:8080"
    restart: unless-stopped

Prometheus Integration

# prometheus.yml
scrape_configs:
  - job_name: cadvisor
    static_configs:
      - targets: ['cadvisor:8080']
    scrape_interval: 15s
    metrics_path: /metrics

Key Metrics

# CPU usage per container (percentage of one core)
rate(container_cpu_usage_seconds_total{name!=""}[5m]) * 100

# Memory usage per container
container_memory_usage_bytes{name!=""}

# Memory limit vs usage
container_memory_usage_bytes{name!=""} / container_spec_memory_limit_bytes{name!=""} * 100

# Network I/O per container
rate(container_network_receive_bytes_total{name!=""}[5m])
rate(container_network_transmit_bytes_total{name!=""}[5m])

# Disk I/O per container
rate(container_fs_reads_bytes_total{name!=""}[5m])
rate(container_fs_writes_bytes_total{name!=""}[5m])

# Container count
count(container_last_seen{name!=""})

# Container restart count
changes(container_start_time_seconds{name!=""}[1h])

Grafana Dashboard

# Import dashboard ID: 14282 (Docker Container & Host Metrics)
# Or ID: 893 (Docker monitoring with cAdvisor)

Alert Rules

groups:
  - name: container_alerts
    rules:
      - alert: ContainerHighCPU
        expr: rate(container_cpu_usage_seconds_total{name!=""}[5m]) > 0.9
        for: 5m
        labels:
          severity: warning
        annotations:
          summary: "Container {{ $labels.name }} CPU > 90%"

      - alert: ContainerHighMemory
        expr: container_memory_usage_bytes{name!=""} / container_spec_memory_limit_bytes{name!=""} > 0.9
        for: 5m
        labels:
          severity: warning

      - alert: ContainerRestarting
        expr: changes(container_start_time_seconds{name!=""}[15m]) > 2
        labels:
          severity: critical
        annotations:
          summary: "Container {{ $labels.name }} restarted {{ $value }} times in 15 minutes"

Best Practices

• Run cAdvisor as a privileged container for full metric collection
• Set a 15-30 second scrape interval — container metrics change rapidly
• Filter out system containers (pause, POD) in Kubernetes environments
• Monitor container memory relative to limits, not absolute usage
• Alert on container restart frequency — frequent restarts indicate application issues
• Use cAdvisor alongside node_exporter for complete infrastructure visibility