Analyzing image layers with dive in Docker - Step-by-Step Execution

Process Flow - Analyzing image layers with dive

Start dive on image

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Load image layers

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Display layer details

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Show file changes per layer

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Analyze wasted space

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User navigates layers

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Exit dive

The tool loads the Docker image layers, shows details and file changes per layer, highlights wasted space, and lets the user explore each layer interactively.

Execution Sample

Docker

dive my-image:latest

Runs dive to analyze the Docker image named 'my-image:latest' layer by layer.

Process Table

Step	Action	Layer Loaded	Files Changed	Wasted Space Detected	User Interaction
1	Start dive command	N/A	N/A	N/A	Loading image layers
2	Load base layer	Layer 1 (base)	50 files added	0 MB	Display layer info
3	Load second layer	Layer 2	10 files modified	2 MB	Highlight wasted space
4	Load third layer	Layer 3	5 files deleted	2.5 MB	User inspects files
5	User navigates to Layer 2	Layer 2	10 files modified	2 MB	Shows detailed file diff
6	User navigates to Layer 3	Layer 3	5 files deleted	2.5 MB	Shows detailed file diff
7	Exit dive	N/A	N/A	N/A	Session ends

💡 User exits dive after inspecting layers and wasted space

Status Tracker

Variable	Start	After Step 2	After Step 3	After Step 4	After Step 5	After Step 6	Final
Current Layer	None	Layer 1	Layer 2	Layer 3	Layer 2	Layer 3	None
Wasted Space (MB)	0	0	2	2.5	2	2.5	0
Files Changed	0	50 added	10 modified	5 deleted	10 modified	5 deleted	0

Key Moments - 2 Insights

Why does dive show wasted space even if files are deleted in a layer?

Because Docker layers are immutable, deleting files in a later layer doesn't remove them from previous layers, so wasted space remains as shown in steps 3 and 4.

How can I tell which layer added or modified a specific file?

By navigating to each layer (steps 5 and 6), dive shows detailed file changes per layer, helping identify where files were added or changed.

Visual Quiz - 3 Questions

Look at the execution table, what is the wasted space after loading Layer 3?

A 2.5 MB

B 0.5 MB

C 2 MB

D 0 MB

💡 Hint

Check the 'Wasted Space Detected' column at step 4 in the execution table.

At which step does the user inspect detailed file differences for Layer 2?

A Step 3

B Step 6

C Step 5

D Step 7

💡 Hint

Look at the 'User Interaction' column for when Layer 2 is selected.

If no files were deleted in Layer 3, how would the wasted space after step 4 change?

A It would increase

B It would decrease

C It would stay the same

D It would be zero

💡 Hint

Refer to the 'Wasted Space (MB)' in variable_tracker after step 4 and consider how deletions affect it.

Concept Snapshot

dive <image>  # Run dive on a Docker image
Shows each image layer's files and changes
Highlights wasted space from unused files
Navigate layers interactively to inspect
Helps optimize image size by spotting inefficiencies

Full Transcript

This visual execution shows how the dive tool analyzes Docker image layers. It starts by loading the image layers one by one, displaying files added, modified, or deleted in each layer. It calculates wasted space caused by leftover files that are no longer needed but still occupy space due to Docker's layer immutability. The user can navigate between layers to see detailed file changes. The session ends when the user exits dive after inspecting the image. Key points include understanding why deleted files still cause wasted space and how to identify which layer changed specific files.