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Monitoring containers

On-Screen

Article from ADMIN 31/2016

By Sebastian Meyer

A monitoring system helps avoid unpleasant surprises during operations, but admins need to modify existing solutions to fit a containerized world.

When administrators monitor containers, they first need to consider what expectations they have with respect to the monitoring tool. Is it important to know the load the containers generate on the host resources, or is availability of the containerized services of more interest? Existing monitoring solutions can be used in part for both use cases.

Rough Overview

Docker [1] offers a variety of information related to the containers [2], but only as a starting point for tools with more complex monitoring approaches. Docker does not format the data, but it does support a couple of commands that at least allow administrators to establish rudimentary container monitoring.

The docker ps command lists all active containers – or those that have run – on a host (Figure 1). This command gives you a rough overview of whether containers are still running and an application is therefore available. Additionally, the command reveals other details, such as open and forwarded ports. If the system terminates an application, you get to see a return code.