How to use docker scout cache df command to check cache usage

Introduction

In this lab, we will learn how to use the docker scout cache df command to understand and manage the Docker Scout cache. We will explore the different components of the cache, including temporary files and cached SBOMs, and learn how to interpret the output of the command to check their disk usage. This will help us effectively monitor and manage the disk space consumed by the Docker Scout cache.

Skills Graph

%%%%{init: {'theme':'neutral'}}%%%% flowchart RL docker(("Docker")) -.-> docker/SystemManagementGroup(["System Management"]) docker/SystemManagementGroup -.-> docker/system("Manage Docker") docker/SystemManagementGroup -.-> docker/prune("Remove Unused Docker Objects") subgraph Lab Skills docker/system -.-> lab-555198{{"How to use docker scout cache df command to check cache usage"}} docker/prune -.-> lab-555198{{"How to use docker scout cache df command to check cache usage"}} end

Understand Docker Scout cache

In this step, we will explore the Docker Scout cache and understand how it stores information about images and their vulnerabilities. Docker Scout uses a local cache to store data like Software Bill of Materials (SBOMs) and vulnerability information, which helps speed up subsequent scans of the same images.

First, let's check the current Docker Scout cache usage. We can use the docker scout cache df command to display information about the cache.

docker scout cache df

This command provides an overview of the disk space used by the Docker Scout cache. The output will show the total size of the cache and the size of different components within the cache, such as temporary files and cached SBOMs. Understanding this output is crucial for managing the cache effectively.

The output typically includes columns like TYPE, COUNT, and SIZE. TYPE indicates the category of cached data (e.g., temp, sbom), COUNT shows the number of items in that category, and SIZE displays the disk space consumed by that category.

Check temporary cache disk usage

In this step, we will focus on understanding the temporary cache usage within Docker Scout. The temporary cache stores intermediate data generated during scanning and analysis. This data is typically short-lived and can be cleaned up to free disk space.

To see the details of the temporary cache, we can again use the docker scout cache df command and observe the output related to the temp type.

docker scout cache df

Look for the row where the TYPE column is temp. The SIZE column in this row indicates the amount of disk space currently used by temporary cache files. This information is useful for identifying if temporary files are consuming excessive disk space.

Understanding the temporary cache size helps in managing the overall cache size and troubleshooting potential disk space issues related to Docker Scout operations.

Check cached SBOMs disk usage

In this step, we will examine the disk space used by cached Software Bill of Materials (SBOMs) in the Docker Scout cache. SBOMs contain detailed information about the components and dependencies within a container image. Caching SBOMs allows Docker Scout to quickly access this information for subsequent scans without needing to re-analyze the image from scratch.

To check the size of the cached SBOMs, we will use the docker scout cache df command again.

docker scout cache df

In the output, locate the row where the TYPE column is sbom. The SIZE column in this row shows the amount of disk space consumed by the cached SBOMs. As you scan more images, the size of the cached SBOMs will likely increase.

Understanding the size of the cached SBOMs helps you gauge how much data Docker Scout is storing about the images you've scanned and can be useful for managing cache size.

Interpret the output of docker scout cache df

In this final step, we will summarize how to interpret the output of the docker scout cache df command and understand its significance for managing your Docker Scout cache.

Recall the output you saw in the previous steps when running docker scout cache df:

docker scout cache df

The output provides a breakdown of the Docker Scout cache usage by type. The key types you will typically see are:

temp: This represents temporary files generated during scanning and analysis. These files are usually short-lived and can be safely removed to free up space.
sbom: This represents cached Software Bill of Materials (SBOMs). These are stored to speed up subsequent scans of the same images.

The COUNT column shows the number of items of each type in the cache, and the SIZE column indicates the disk space consumed by each type. The TOTAL row provides the overall size of the Docker Scout cache.

By regularly checking the output of docker scout cache df, you can:

Monitor the growth of your Docker Scout cache.
Identify which types of cached data are consuming the most disk space.
Determine if temporary files are accumulating unnecessarily.
Make informed decisions about when to clean up the cache to free up disk space.

Understanding this output is essential for maintaining a healthy and efficient Docker Scout environment, especially when dealing with a large number of images or limited disk space.

Summary

In this lab, we learned how to use the docker scout cache df command to understand and check the disk usage of the Docker Scout cache. We explored the overall cache usage, focusing on how it stores SBOMs and vulnerability information to accelerate subsequent scans.

Specifically, we examined the output of docker scout cache df to identify the disk space consumed by different cache components, such as temporary files (temp) and cached SBOMs (sbom). Understanding the TYPE, COUNT, and SIZE columns in the output is essential for interpreting cache usage and managing disk space effectively.