[Awesome Software Disk] Dive: A tool for exploring a docker image, layer contents, and discovering ways to shrink the size of your Docker/OCI image.

Posted on Edited on In , , Views: Word count in article: 4k Reading time ≈ 4 mins.

Dive

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

Dive

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: dive build -t some-tag .

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

  • Multiple Image Sources and Container Engines Supported

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

1
$ dive <your-image> --source <source>

Installation

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
# macOS
$ brew install dive

# Ubuntu/Debian
$ wget https://github.com/wagoodman/dive/releases/download/v0.9.2/dive_0.9.2_linux_amd64.deb
$ sudo apt install ./dive_0.9.2_linux_amd64.deb

# RHEL/Centos
$ curl -OL https://github.com/wagoodman/dive/releases/download/v0.9.2/dive_0.9.2_linux_amd64.rpm
$ rpm -i dive_0.9.2_linux_amd64.rpm

# Arch Linux
# Available as dive in the Arch User Repository (AUR).
yay -S dive

See [Installation | wagoodman/dive: A tool for exploring each layer in a docker image - https://github.com/wagoodman/dive#installation](https://github.com/wagoodman/dive#installation) to learn more.

## Usages

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

```shell
$ dive <your-image-tag>

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

1
$ dive build -t <some-tag> .

CI Integration

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

1
$ CI=true dive <your-image>

UI Configuration

No configuration is necessary, however, you can create a config file and override values:

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
# supported options are "docker" and "podman"
container-engine: docker
# continue with analysis even if there are errors parsing the image archive
ignore-errors: false
log:
  enabled: true
  path: ./dive.log
  level: info

# Note: you can specify multiple bindings by separating values with a comma.
# Note: UI hinting is derived from the first binding
keybinding:
  # Global bindings
  quit: ctrl+c
  toggle-view: tab
  filter-files: ctrl+f, ctrl+slash

  # Layer view specific bindings
  compare-all: ctrl+a
  compare-layer: ctrl+l

  # File view specific bindings
  toggle-collapse-dir: space
  toggle-collapse-all-dir: ctrl+space
  toggle-added-files: ctrl+a
  toggle-removed-files: ctrl+r
  toggle-modified-files: ctrl+m
  toggle-unmodified-files: ctrl+u
  toggle-filetree-attributes: ctrl+b
  page-up: pgup
  page-down: pgdn

diff:
  # You can change the default files shown in the filetree (right pane). All diff types are shown by default.
  hide:
    - added
    - removed
    - modified
    - unmodified

filetree:
  # The default directory-collapse state
  collapse-dir: false

  # The percentage of screen width the filetree should take on the screen (must be >0 and <1)
  pane-width: 0.5

  # Show the file attributes next to the filetree
  show-attributes: true

layer:
  # Enable showing all changes from this layer and every previous layer
  show-aggregated-changes: false

dive will search for configs in the following locations:

  • $XDG_CONFIG_HOME/dive/*.yaml

  • $XDG_CONFIG_DIRS/dive/*.yaml

  • ~/.config/dive/*.yaml

  • ~/.dive.yaml

References

[1] wagoodman/dive: A tool for exploring each layer in a docker image - https://github.com/wagoodman/dive

[2] docker history | Docker Documentation - https://docs.docker.com/engine/reference/commandline/history/

[3] Empowering App Development for Developers | Docker - https://www.docker.com/