Understand Docker Monitoring – And Its Relationship to Container Security

What is Docker monitoring?

Docker monitoring is the practice of tracking the health and performance of Docker containers.

Docker containers are lightweight hosting environments that isolate applications from each other, even when multiple containers run on the same physical server. In this respect, Docker containers provide some benefits of traditional virtualization; however, unlike traditional virtualization, Docker containers are more efficient and consume fewer resources since they don’t require the use of a hypervisor. Nor does each container have to run a standalone guest operating system.

Note that in the narrow sense, Docker monitoring refers to tracking containers that are built and launched using Docker, the platform that helped bring container technology mainstream. Today, however, Docker is only one of many platforms for building and running containers.

Nonetheless, because Docker was the first container platform to gain widespread popularity, “Docker” became something of a shorthand for containers in general (kind of like how “Xerox” refers to photocopier machines of all types, not just those made by Xerox). As a result, when people talk about “Docker monitoring” today, they sometimes mean monitoring any type of container, not just those that are built using Docker tools or deployed using the Docker runtime. And in general, the same tools and practices that can monitor Docker containers can also monitor containers based on any other mainstream platform.

The importance of Docker monitoring

Docker monitoring is essential for the same reasons as monitoring any type of application or service: Many things can go wrong when operating software, and monitoring helps teams identify and respond to issues before they turn into critical problems.

For example, Docker monitoring can help identify problems such as:

• Containers that failed to start due to issues like a misconfiguration inside the container.
• Containers that have crashed because of issues like buggy code.
• Containers that have maxed out their available CPU or memory resources, and that are struggling to perform adequately as a result.
• Attempts by one container to access resources that should only be available to other containers.

When you detect these issues early-on using Docker monitoring tools, you can fix them before they disrupt end-users.

In addition, Docker monitoring can help to reduce application hosting costs by identifying instances where containers are using significantly fewer resources than those allocated to them. It can also help to detect some types of security risks associated with containers – although as we note below, Docker monitoring is not a substitute for dedicated container security monitoring.

Top 7 Docker monitoring tools – open source and proprietary

A variety of tools are available today – including both open source and proprietary options – for monitoring Docker containers.

Open source container monitoring tools

In the open source realm, popular Docker container monitoring options include:

• Prometheus, which is probably the most widely used open source monitoring tool today.
• Zabbix, another mainstream open source monitoring solution that supports containers.
• cAdvisor, a monitoring tool designed for containers specifically.
• Jaeger, a tracing tool that can be useful for pinpointing the source of performance issues within Dockerized applications, especially those that are deployed as microservices.

Proprietary tools for Docker monitoring

The list of proprietary and closed-source Docker monitoring tools is long because virtually all commercial monitoring and observability software today supports containers. Here are some of the more widely used options:

• Datadog.
• New Relic.
• Dynatrace.
• Splunk.

While these tools vary a bit in their features, they are all widely used monitoring platforms that support containers as well as most other types of workloads and environments.

Docker monitoring best practices

Effective Docker monitoring requires more than simply deploying monitoring tools. To get the most value from Docker monitoring, consider the following best practices.

Generate meaningful alerts

Configure Docker monitoring tools to alert you to anomalies so that your team becomes aware of issues as they arise. Be careful, however, to avoid alerting on low-priority or redundant issues, which could distract your engineers.

Contextualize alerts

The more information you include in Docker monitoring alerts, the easier it is for your team to troubleshoot the issue quickly. Alerts should include information like which resources are affected and which events or anomalies correlate with the alert data.

Monitor the entire stack

Docker containers are only one layer of the stack that hosts applications. The underlying server operating system, the network, and any orchestration platform (like Kubernetes) that you use to manage containers are also important layers.

To monitor effectively, you should collect and correlate information from across your entire stack. This is important because it helps you identify the root cause of problems. For example, if a container has become slow to respond, monitoring data from the entire stack will help you determine whether the issue is that your host server is low on resources, you have a configuration issue with your orchestrator, or the container itself is buggy.

Use diverse monitoring techniques

There are multiple types of data sources (like metrics, logs, and traces) that you can use to gain insight into the health and performance of Docker containers. Effective monitoring requires collecting and analyzing all relevant data to maximize the chances of discovering relevant anomalies. In addition, collecting more data helps to provide greater context for identifying the root cause of issues.

Why container monitoring isn’t enough – and how Aqua can help

The Docker monitoring tools and practices we’ve described above are useful for managing the health and performance of Docker-based applications. But the degree to which they can mitigate security issues is limited.

To some extent, traditional Docker monitoring can help with container security because it allows you to identify anomalous events that could be a sign of security problems. For example, monitoring tools would typically alert you to a sudden spike in CPU usage, which could happen if a threat actor were to deploy a cryptojacker inside a container.

However, Docker monitoring tools don’t typically provide the capabilities necessary to confirm that anomalies are definitely security issues, let alone remediate them. Monitoring tools will not, for example, tell you whether you are using insecure Docker container images, or whether you’ve configured your containers in ways that could lead to security breaches.

This is why it’s critical to complement Docker monitoring tools with an effective container security solution. As the first security platform designed from the start to protect containerized and cloud-native workloads, Aqua offers the broad range of Docker testing and scanning capabilities necessary to identify and respond to Docker security risks at all stages of the software development lifecycle.

See for yourself by requesting a demo.