Superdive

A tool for exploring a Docker image, layer contents, and discovering ways to shrink the size of your Docker/OCI image.

Installation

npm (recommended)

npm install -g superdive

yarn

yarn global add superdive

From source

git clone https://github.com/dukaev/superdive.git
cd superdive
go build -o superdive ./cmd/dive

Usage

To analyze a Docker image simply run superdive with an image tag/id/digest:

superdive <your-image-tag>

Or if you want to build your image then jump straight into analyzing it:

superdive build -t <some-tag> .

Additionally you can run this in your CI pipeline to ensure you're keeping wasted space to a minimum (this skips the UI):

CI=true superdive <your-image>

Basic Features

Show Docker image contents broken down by layer

As you select a layer on the left, you are shown the contents of that layer combined with all previous layers on the right. Also, you can fully explore the file tree with the arrow keys.

Indicate what's changed in each layer

Files that have changed, been modified, added, or removed are indicated in the file tree. This can be adjusted to show changes for a specific layer, or aggregated changes up to this layer.

Estimate "image efficiency"

The lower left pane shows basic layer info and an experimental metric that will guess how much wasted space your image contains. This might be from duplicating files across layers, moving files across layers, or not fully removing files. Both a percentage "score" and total wasted file space is provided.

Quick build/analysis cycles

You can build a Docker image and do an immediate analysis with one command:

superdive build -t some-tag .

You only need to replace your docker build command with the same superdive build command.

CI Integration

Analyze an image and get a pass/fail result based on the image efficiency and wasted space. Simply set CI=true in the environment when invoking any valid superdive command.

Multiple Image Sources and Container Engines Supported

With the --source option, you can select where to fetch the container image from:

superdive <your-image> --source <source>

or

superdive <source>://<your-image>

With valid source options as such:

• docker: Docker engine (the default option)
• docker-archive: A Docker Tar Archive from disk
• podman: Podman engine (linux only)

CI Integration

When running superdive with the environment variable CI=true then the UI will be bypassed and will instead analyze your docker image, giving it a pass/fail indication via return code. Currently there are three metrics supported via a .dive-ci file that you can put at the root of your repo:

rules:
  # If the efficiency is measured below X%, mark as failed.
  # Expressed as a ratio between 0-1.
  lowestEfficiency: 0.95

  # If the amount of wasted space is at least X or larger than X, mark as failed.
  # Expressed in B, KB, MB, and GB.
  highestWastedBytes: 20MB

  # If the amount of wasted space makes up for X% or more of the image, mark as failed.
  # Note: the base image layer is NOT included in the total image size.
  # Expressed as a ratio between 0-1; fails if the threshold is met or crossed.
  highestUserWastedPercent: 0.20

You can override the CI config path with the --ci-config option.

License

MIT