Resource monitoring per container in Docker - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the command to show resource usage statistics for all running containers.

Docker

docker [1]

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

Astats

Bimages

Cps

Drun

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'docker ps' which lists containers but does not show resource usage.

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

Using 'docker run' which starts a container but does not show stats.

The docker stats command displays live resource usage statistics for running containers.

2fill in blank

medium

Complete the command to monitor resource usage for a specific container named 'webapp'.

Docker

docker stats [1]

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

A--all

B--no-stream

Cwebapp

Dcontainer_id

Attempts:

3 left

💡 Hint

Common Mistakes

Using '--all' which shows all containers, not just one.

Using '--no-stream' which changes output mode but does not specify container.

Using 'container_id' without knowing the actual ID.

To monitor a specific container, provide its name or ID after docker stats. Here, the container name is 'webapp'.

3fill in blank

hard

Fix the error in the command to show resource stats for container 'db' without continuous updates.

Docker

docker stats [1] db

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

A--no-stream

B--all

C--quiet

D--filter

Attempts:

3 left

💡 Hint

Common Mistakes

Using '--all' which shows all containers.

Using '--quiet' which suppresses output.

Using '--filter' which filters containers but does not stop streaming.

The --no-stream option shows a single snapshot of resource usage instead of continuous updates.

4fill in blank

hard

Fill both blanks to create a command that shows resource stats for all containers including stopped ones.

Docker

docker stats [1] [2]

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

A--all

B--no-stream

C--no-trunc

D--format

Attempts:

3 left

💡 Hint

Common Mistakes

Using '--no-trunc' which affects output formatting, not container selection.

Using '--format' which changes output style but not container selection.

The --all option includes all containers, and --no-stream shows a single snapshot.

5fill in blank

hard

Fill all three blanks to format the stats output to show only container name, CPU %, and memory usage.

Docker

docker stats --no-stream --format "{{.[1]: CPU [2], Mem [3]"

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

AName

B.CPUPerc

C.MemUsage

DID

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'ID' instead of 'Name' for container name.

Omitting the dot prefix in CPU and memory fields.

Mixing up CPU and memory field names.

The --format option uses Go templates. Name shows container name, .CPUPerc CPU percentage, and .MemUsage memory usage.

Practice

1. What does the docker stats command show for each running container?

easy

A. The container's file system contents

B. The container's log output

C. Live resource usage like CPU, memory, network, and disk I/O

D. The container's environment variables

Solution

1. Step 1: Understand the purpose of docker stats

   The docker stats command is designed to show live resource usage statistics for running containers.

2. Step 2: Identify the resources monitored

   It monitors CPU, memory, network I/O, and disk I/O per container to help track performance.

3. Final Answer:

   Live resource usage like CPU, memory, network, and disk I/O -> Option C

4. Quick Check:

   docker stats = Live resource usage [OK]

Hint: Remember: docker stats shows live resource use per container [OK]

Common Mistakes:

• Confusing docker stats with docker logs
• Thinking it shows file system contents
• Assuming it shows environment variables

2. Which of the following is the correct command to show live resource usage for all running Docker containers?

easy

A. docker stats

B. docker monitor

C. docker inspect stats

D. docker top

Solution

1. Step 1: Recall the command for resource monitoring

   The command docker stats is the official Docker command to show live resource usage for containers.

2. Step 2: Verify other options

   docker monitor and docker inspect stats are invalid commands, and docker top shows running processes, not resource stats.

3. Final Answer:

   docker stats -> Option A

4. Quick Check:

   Correct command = docker stats [OK]

Hint: Use 'docker stats' to see live container resource use [OK]

Common Mistakes:

• Using docker top to check resource usage
• Trying docker monitor which doesn't exist
• Confusing docker inspect with stats

3. You run docker stats --no-stream on a container. What will you see?

medium

A. Continuous live updates of resource usage

B. A single snapshot of current resource usage

C. Only CPU usage without memory info

D. Error because --no-stream is invalid

Solution

1. Step 1: Understand the --no-stream option

   The --no-stream option tells docker stats to show resource usage only once, not continuously.

2. Step 2: Identify the output behavior

   It outputs a single snapshot of CPU, memory, network, and disk I/O usage at the moment the command runs.

3. Final Answer:

   A single snapshot of current resource usage -> Option B

4. Quick Check:

   --no-stream = single snapshot [OK]

Hint: Use --no-stream for one-time resource snapshot [OK]

Common Mistakes:

• Expecting continuous updates with --no-stream
• Thinking it shows only CPU usage
• Assuming --no-stream is invalid

4. You try to run docker stats --format '{{.CPUPerc}} but get no output. What is the likely problem?

medium

A. The format string is missing a closing single quote

B. The container is stopped, so no stats show

C. The --format option is not supported in docker stats

D. You need to add --no-stream to see output

Solution

1. Step 1: Check the format string syntax

   The command uses --format '{{.CPUPerc}} which is missing the closing single quote after the curly braces.

2. Step 2: Understand impact of missing quote

   Without the closing quote, the shell or Docker cannot parse the format string, so no output appears.

3. Final Answer:

   The format string is missing a closing single quote -> Option A

4. Quick Check:

   Format string syntax error = missing quote [OK]

Hint: Always close quotes in --format strings [OK]

Common Mistakes:

• Assuming stopped containers show no stats (they do not appear in stats)
• Thinking --format is unsupported
• Believing --no-stream is required for output

5. You want to monitor CPU and memory usage of a specific container named webapp and save the output once to a file. Which command should you use?

hard

A. docker stats --stream=false webapp > usage.txt

B. docker stats webapp --output usage.txt

C. docker monitor webapp > usage.txt

D. docker stats --no-stream --format 'table {{.Name}}\t{{.CPUPerc}}\t{{.MemUsage}}' webapp > usage.txt

Solution

1. Step 1: Choose the correct command and options

   To get a one-time snapshot, use --no-stream. To format output with container name, CPU, and memory, use --format with a table layout.

2. Step 2: Redirect output to a file

   Use shell redirection > usage.txt to save the output to a file named usage.txt.

3. Final Answer:

   docker stats --no-stream --format 'table {{.Name}}\t{{.CPUPerc}}\t{{.MemUsage}}' webapp > usage.txt -> Option D

4. Quick Check:

   One-time formatted output saved to file = docker stats --no-stream --format 'table {{.Name}}\t{{.CPUPerc}}\t{{.MemUsage}}' webapp > usage.txt [OK]

Hint: Use --no-stream and --format, redirect output to file [OK]

Common Mistakes:

• Using invalid docker monitor command
• Assuming --output option exists
• Using --stream=false instead of --no-stream