A monitoring solution for Docker hosts and containers with Prometheus, Grafana, cAdvisor, NodeExporter and alerting with AlertManager.

Clone this repository on your Docker host, cd into dockprom directory and run compose up:

• $ git clone https://github.com/stefanprodan/dockprom
• $ cd dockprom
• $ docker-compose up -d

Containers:

• Prometheus (metrics database) http://<host-ip>:9090
• AlertManager (alerts management) http://<host-ip>:9093
• Grafana (visualize metrics) http://<host-ip>:3000
• NodeExporter (host metrics collector)
• cAdvisor (containers metrics collector)

While Grafana supports authentication, the Prometheus and AlertManager services have no such feature. You can remove the ports mapping from the docker-compose file and use NGINX as a reverse proxy providing basic authentication for Prometheus and AlertManager.

Navigate to http://<host-ip>:3000 and login with user admin password changeme. You can change the password from Grafana UI or by modifying the user.config file.

From the Grafana menu, choose Data Sources and click on Add Data Source. Use the following values to add the Prometheus container as data source:

• Name: Prometheus
• Type: Prometheus
• Url: http://prometheus:9090
• Access: proxy

Now you can import the dashboard temples from the grafana directory. From the Grafana menu, choose Dashboards and click on Import.

Docker Host Dashboard

The Docker Host Dashboard shows key metrics for monitoring the resource usage of your server:

• Server uptime, CPU idle percent, number of CPU cores, available memory, swap and storage
• System load average graph, running and blocked by IO processes graph, interrupts graph
• CPU usage graph by mode (guest, idle, iowait, irq, nice, softirq, steal, system, user)
• Memory usage graph by distribution (used, free, buffers, cached)
• IO usage graph (read Bps, read Bps and IO time)
• Network usage graph by device (inbound Bps, Outbound Bps)
• Swap usage and activity graphs

Docker Containers Dashboard

The Docker Containers Dashboard shows key metrics for monitoring running containers:

• Total containers CPU load, memory and storage usage
• Running containers graph, system load graph, IO usage graph
• Container CPU usage graph
• Container memory usage graph
• Container cached memory usage graph
• Container network inbound usage graph
• Container network outbound usage graph

Note that this dashboard doesn't show the containers that are part of the monitoring stack.

Monitor Services Dashboard

The Monitor Services Dashboard shows key metrics for monitoring the containers that make up the monitoring stack:

• Prometheus container uptime, monitoring stack total memory usage, Prometheus local storage memory chunks and series
• Container CPU usage graph
• Container memory usage graph
• Prometheus chunks to persist and persistence urgency graphs
• Prometheus chunks ops and checkpoint duration graphs
• Prometheus samples ingested rate, target scrapes and scrape duration graphs
• Prometheus HTTP requests graph
• Prometheus alerts graph

Prometheus memory usage can be controlled by adjusting the local storage memory chunks. You can modify the max chunks value in docker-compose.yml. I've set the storage.local.memory-chunks value to 100000, if you monitor 10 containers, then Prometheus will use around 1GB of RAM.

I've setup three alerts configuration files:

• Monitoring services alerts targets.rules
• Docker Host alerts hosts.rules
• Docker Containers alerts containers.rules

You can modify the alert rules and reload them by making a HTTP POST call to Prometheus:

curl -X POST http://<host-ip>:9090/-/reload

Monitoring services alerts

Trigger an alert if any of the monitoring targets (node-exporter and cAdvisor) are down for more than 30 seconds:

ALERT monitor_service_down
  IF up == 0
  FOR 30s
  LABELS { severity = "critical" }
  ANNOTATIONS {
      summary = "Monitor service non-operational",
      description = "{{ $labels.instance }} service is down.",
  }

Docker Host alerts

Trigger an alert if the Docker host CPU is under hight load for more than 30 seconds:

ALERT high_cpu_load
  IF node_load1 > 1.5
  FOR 30s
  LABELS { severity = "warning" }
  ANNOTATIONS {
      summary = "Server under high load",
      description = "Docker host is under high load, the avg load 1m is at {{ $value}}. Reported by instance {{ $labels.instance }} of job {{ $labels.job }}.",
  }

Modify the load threshold based on your CPU cores.

Trigger an alert if the Docker host memory is almost full:

ALERT high_memory_load
  IF (sum(node_memory_MemTotal) - sum(node_memory_MemFree + node_memory_Buffers + node_memory_Cached) ) / sum(node_memory_MemTotal) * 100 > 85
  FOR 30s
  LABELS { severity = "warning" }
  ANNOTATIONS {
      summary = "Server memory is almost full",
      description = "Docker host memory usage is {{ humanize $value}}%. Reported by instance {{ $labels.instance }} of job {{ $labels.job }}.",
  }

Trigger an alert if the Docker host storage is almost full:

ALERT hight_storage_load
  IF (node_filesystem_size{fstype="aufs"} - node_filesystem_free{fstype="aufs"}) / node_filesystem_size{fstype="aufs"}  * 100 > 85
  FOR 30s
  LABELS { severity = "warning" }
  ANNOTATIONS {
      summary = "Server storage is almost full",
      description = "Docker host storage usage is {{ humanize $value}}%. Reported by instance {{ $labels.instance }} of job {{ $labels.job }}.",
  }

Docker Containers alerts

Trigger an alert if a container is down for more than 30 seconds:

ALERT jenkins_down
  IF absent(container_memory_usage_bytes{name="jenkins"})
  FOR 30s
  LABELS { severity = "critical" }
  ANNOTATIONS {
    summary= "Jenkins down",
    description= "Jenkins container is down for more than 30 seconds."
  }

Trigger an alert if a container is using more than 10% of total CPU cores for more than 30 seconds:

 ALERT jenkins_high_cpu
  IF sum(rate(container_cpu_usage_seconds_total{name="jenkins"}[1m])) / count(node_cpu{mode="system"}) * 100 > 10
  FOR 30s
  LABELS { severity = "warning" }
  ANNOTATIONS {
    summary= "Jenkins high CPU usage",
    description= "Jenkins CPU usage is {{ humanize $value}}%."
  }

Trigger an alert if a container is using more than 1,2GB of RAM for more than 30 seconds:

ALERT jenkins_high_memory
  IF sum(container_memory_usage_bytes{name="jenkins"}) > 1200000000
  FOR 30s
  LABELS { severity = "warning" }
  ANNOTATIONS {
      summary = "Jenkins high memory usage",
      description = "Jenkins memory consumption is at {{ humanize $value}}.",
  }

The AlertManager service is responsible for handling alerts sent by Prometheus server. AlertManager can send notifications via email, Pushover, Slack, HipChat or any other system that exposes a webhook interface. A complete list of integrations can be found here.

You can view and silence notifications by accessing http://<host-ip>:9093.

The notification receivers can be configured in alertmanager/config.yml file.

To receive alerts via Slack you need to make a custom integration by choose incoming web hooks in your Slack team app page. You can find more details on setting up Slack integration here.

Copy the Slack Webhook URL into the api_url field and specify a Slack channel.

route:
    receiver: 'slack'

receivers:
    - name: 'slack'
      slack_configs:
          - send_resolved: true
            text: "{{ .CommonAnnotations.description }}"
            username: 'Prometheus'
            channel: '#<channel>'
            api_url: 'https://hooks.slack.com/services/<webhook-id>'