Inspecting container details in Docker - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the command to list all running Docker containers.

Docker

docker [1]

Drag options to blanks, or click blank then click option'

Aps

Bstart

Cimages

Drun

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'docker run' which starts a new container instead of listing.

Using 'docker images' which lists images, not containers.

The docker ps command lists all running containers.

2fill in blank

medium

Complete the command to show detailed information about a container named 'webapp'.

Docker

docker container [1] webapp

Drag options to blanks, or click blank then click option'

Alogs

Bstart

Cinspect

Drm

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'logs' which shows output logs, not detailed info.

Using 'start' which runs the container instead of inspecting.

The docker container inspect command shows detailed info about a container.

3fill in blank

hard

Fix the error in the command to get the IP address of a container named 'db'. Fill the missing option.

Docker

docker inspect --format='{{.NetworkSettings.IPAddress}}' [1]

Drag options to blanks, or click blank then click option'

Adb

B--ip

Cnetwork

Dcontainer

Attempts:

3 left

💡 Hint

Common Mistakes

Using an option like '--ip' instead of the container name.

Using 'network' or 'container' which are not valid here.

The last argument should be the container name or ID, here 'db'.

4fill in blank

hard

Fill both blanks to create a command that shows the logs of a container named 'api' and follows new output.

Docker

docker logs [1] [2]

Drag options to blanks, or click blank then click option'

A-f

Bapi

C--follow

D-t

Attempts:

3 left

💡 Hint

Common Mistakes

Putting the container name before the option.

Using '-t' which shows timestamps but does not follow logs.

The container name 'api' is needed, and --follow makes logs stream new output.

5fill in blank

hard

Fill all three blanks to create a command that inspects a container named 'cache' and formats output to show only its state status.

Docker

docker inspect --format='{{.[1].[2]' [3]

Drag options to blanks, or click blank then click option'

AState

BStatus

Ccache

DConfig

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'Config' instead of 'State' for the first blank.

Using 'cache' as a format field instead of container name argument.

The format string accesses .State.Status of the container named 'cache'.

Practice

1. What does the command docker inspect CONTAINER do?

easy

A. Shows detailed JSON information about the specified container

B. Starts the specified container

C. Deletes the specified container

D. Lists all running containers

Solution

1. Step 1: Understand the command purpose

   The docker inspect command is used to get detailed information about Docker objects like containers.

2. Step 2: Identify the output type

   It returns detailed JSON data about the container's configuration and state.

3. Final Answer:

   Shows detailed JSON information about the specified container -> Option A

4. Quick Check:

   docker inspect = detailed JSON info [OK]

Hint: Remember: inspect means see detailed info [OK]

Common Mistakes:

• Confusing inspect with start or delete commands
• Expecting a simple list instead of JSON output
• Using inspect without specifying a container

2. Which of the following is the correct syntax to get only the container's IP address using docker inspect?

easy

A. docker inspect --format='{{.NetworkSettings.IPAddress}}' CONTAINER

B. docker inspect --ip CONTAINER

C. docker inspect -ip CONTAINER

D. docker inspect --format='{{IPAddress}}' CONTAINER

Solution

1. Step 1: Recall the --format option usage

   The --format flag uses Go templates to extract specific fields from the JSON output.

2. Step 2: Identify the correct template for IP address

   The IP address is under .NetworkSettings.IPAddress, so the correct syntax is {{.NetworkSettings.IPAddress}}.

3. Final Answer:

   docker inspect --format='{{.NetworkSettings.IPAddress}}' CONTAINER -> Option A

4. Quick Check:

   Use --format with correct JSON path [OK]

Hint: Use --format with full JSON path in double braces [OK]

Common Mistakes:

• Using incorrect flags like --ip or -ip
• Missing the dot before NetworkSettings in template
• Not quoting the template string properly

3. Given a container named webapp, what will the command docker inspect --format='{{.State.Status}}' webapp output if the container is running?

medium

A. created

B. paused

C. exited

D. running

Solution

1. Step 1: Understand the .State.Status field

   The .State.Status field shows the current status of the container, such as running, exited, paused, or created.

2. Step 2: Match the container state

   If the container is running, the output will be the string running.

3. Final Answer:

   running -> Option D

4. Quick Check:

   .State.Status = running when container runs [OK]

Hint: Check .State.Status for container current state [OK]

Common Mistakes:

• Confusing status with container name or ID
• Expecting JSON output instead of plain string
• Using wrong field like .Status instead of .State.Status

4. You run docker inspect --format='{{.Config.Env}}' mycontainer but get an error. What is the most likely cause?

medium

A. The container name is misspelled

B. The format string syntax is incorrect

C. The .Config.Env field does not exist in the container JSON

D. The container is not running

Solution

1. Step 1: Check the format string syntax

   The .Config.Env field is an array, so printing it directly requires proper formatting.

2. Step 2: Identify the syntax error

   Using {{.Config.Env}} tries to print an array directly, which causes a template error. You need to format it, for example with {{range .Config.Env}}{{println .}}{{end}}.

3. Final Answer:

   The format string syntax is incorrect -> Option B

4. Quick Check:

   Arrays need special formatting in --format [OK]

Hint: Arrays need loops in --format templates [OK]

Common Mistakes:

• Assuming all fields print directly without formatting
• Ignoring container name correctness
• Thinking container must be running to inspect

5. You want to list all container names and their IP addresses in a simple format. Which command correctly achieves this?

hard

A. docker ps -q | xargs -n1 docker inspect --format='{{.Name}} {{.NetworkSettings.IPAddress}}'

B. docker ps --format='{{.Name}} {{.NetworkSettings.IPAddress}}'

C. docker inspect --format='{{.Name}} {{.NetworkSettings.IPAddress}}' $(docker ps -q)

D. docker inspect $(docker ps) --format='{{.Name}} {{.NetworkSettings.IPAddress}}'

Solution

1. Step 1: Understand how to get container IDs

   docker ps -q lists container IDs only, which can be passed to docker inspect.

2. Step 2: Use inspect with multiple container IDs and format

   Passing IDs as arguments to docker inspect with --format outputs info for each container. docker inspect --format='{{.Name}} {{.NetworkSettings.IPAddress}}' $(docker ps -q) uses this correctly.

3. Step 3: Check other options for errors

   docker ps -q | xargs -n1 docker inspect --format='{{.Name}} {{.NetworkSettings.IPAddress}}' uses xargs but may break if container names have spaces. docker ps --format='{{.Name}} {{.NetworkSettings.IPAddress}}' is invalid because docker ps does not support .NetworkSettings.IPAddress. docker inspect $(docker ps) --format='{{.Name}} {{.NetworkSettings.IPAddress}}' uses wrong syntax for docker ps.

4. Final Answer:

   docker inspect --format='{{.Name}} {{.NetworkSettings.IPAddress}}' $(docker ps -q) -> Option C

5. Quick Check:

   Use docker inspect with IDs from docker ps -q [OK]

Hint: Use docker inspect with IDs from docker ps -q [OK]

Common Mistakes:

• Trying to get IP from docker ps directly
• Using wrong command substitution syntax
• Not passing container IDs correctly to inspect