Volumes for persistent data in Docker - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the Docker command to create a volume named 'mydata'.

Docker

docker volume [1] mydata

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

Abuild

Bcreate

Crun

Dstart

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'docker volume run' instead of 'create'.

Trying to create volume with 'docker run'.

The docker volume create command creates a new volume. Other commands like build, run, or start do not create volumes.

2fill in blank

medium

Complete the Docker run command to mount a volume named 'mydata' to '/app/data' inside the container.

Docker

docker run -v [1]:/app/data myimage

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

Amydata

B/mydata

Cmydata:/app/data

Dmydata:/data

Attempts:

3 left

💡 Hint

Common Mistakes

Adding slashes before volume name.

Using incorrect path after colon.

When mounting a volume by name, use -v volume_name:container_path. Here, mydata is the volume name, and /app/data is the container path.

3fill in blank

hard

Fix the error in the Docker run command to mount a host directory '/data' as a volume inside the container at '/app/data'.

Docker

docker run -v [1]:/app/data myimage

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

A/app/data

Bdata

C/data

Dmydata

Attempts:

3 left

💡 Hint

Common Mistakes

Using volume name instead of host path.

Omitting the leading slash.

To mount a host directory, use the full path on the host before the colon. Here, /data is the host directory.

4fill in blank

hard

Fill both blanks to create a volume and then run a container mounting it at '/data'.

Docker

docker volume [1] myvol && docker run -v [2]:/data alpine

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

Acreate

Bmyvol

Cmyvolume

Dstart

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'start' instead of 'create'.

Mismatch between volume name in create and run commands.

First, create the volume with docker volume create myvol. Then run the container mounting myvol at /data.

5fill in blank

hard

Fill all three blanks to define a Docker Compose volume and mount it to '/var/lib/mysql' in the service.

Docker

version: '3.8'
services:
  db:
    image: mysql
    volumes:
      - [1]:/var/lib/mysql
volumes:
  [2]:
    [3]: local

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

Adbdata

Cdriver

Dlocal

Attempts:

3 left

💡 Hint

Common Mistakes

Using different volume names in service and volumes.

Omitting the driver key or using wrong value.

The volume name dbdata is used in both the service and volumes section. The driver key is set to local to use the default volume driver.

Practice

1. What is the main purpose of using volumes in Docker containers?

easy

A. To limit container CPU usage

B. To store data persistently outside the container lifecycle

C. To speed up container startup time

D. To create network connections between containers

Solution

1. Step 1: Understand container storage

   Containers are temporary and lose data when removed unless data is stored outside.

2. Step 2: Role of volumes

   Volumes provide a way to save data persistently on the host, independent of container lifecycle.

3. Final Answer:

   To store data persistently outside the container lifecycle -> Option B

4. Quick Check:

   Persistent data = volumes [OK]

Hint: Volumes keep data safe even if container is deleted [OK]

Common Mistakes:

• Confusing volumes with container CPU limits
• Thinking volumes speed up container start
• Mixing volumes with networking features

2. Which of the following is the correct Docker CLI syntax to create a named volume called mydata?

easy

A. docker create volume mydata

B. docker volume new mydata

C. docker volume create mydata

D. docker volume make mydata

Solution

1. Step 1: Recall Docker volume creation command

   The correct command to create a volume is docker volume create <name>.

2. Step 2: Match syntax

   docker volume create mydata matches the correct syntax exactly.

3. Final Answer:

   docker volume create mydata -> Option C

4. Quick Check:

   Volume create command = docker volume create [OK]

Hint: Use 'docker volume create' to make volumes [OK]

Common Mistakes:

• Using 'create volume' instead of 'volume create'
• Using 'new' or 'make' which are invalid commands
• Mixing order of words in the command

3. Given the Docker run command:
docker run -d -v myvol:/app/data nginx
What happens to the data inside /app/data when the container is removed?

medium

A. Data remains in the named volume myvol

B. Data is deleted with the container

C. Data is copied to the host's home directory

D. Data is lost unless backed up manually

Solution

1. Step 1: Understand named volume behavior

   Named volumes like myvol store data persistently on the host.

2. Step 2: Effect of container removal

   Removing the container does not delete the named volume or its data.

3. Final Answer:

   Data remains in the named volume myvol -> Option A

4. Quick Check:

   Named volume data persists after container removal [OK]

Hint: Named volumes keep data safe after container removal [OK]

Common Mistakes:

• Assuming data deletes with container
• Confusing named volumes with anonymous volumes
• Thinking data copies to host home directory automatically

4. You run this command:
docker run -v /data nginx
But it fails with an error. What is the problem?

medium

A. Missing container path in volume syntax

B. Volume name /data is invalid

C. Nginx image does not support volumes

D. Docker daemon is not running

Solution

1. Step 1: Check volume syntax

   The correct volume syntax requires host_path:container_path or volume_name:container_path.

2. Step 2: Identify missing part

   Here, only one path /data is given, missing container path.

3. Final Answer:

   Missing container path in volume syntax -> Option A

4. Quick Check:

   Volume syntax needs host:container paths [OK]

Hint: Volume syntax needs two paths separated by colon [OK]

Common Mistakes:

• Using only one path in -v option
• Blaming image for volume errors
• Ignoring Docker daemon status

5. You want to share persistent data between two containers using a named volume sharedvol. Which Docker commands correctly achieve this?

hard

A. docker volume create sharedvoldocker run -v sharedvol container1docker run -v sharedvol container2

B. docker run -v sharedvol:/data container1docker run -v sharedvol:/data container2

C. docker volume create sharedvoldocker run -v /data sharedvol container1docker run -v /data sharedvol container2

D. docker volume create sharedvoldocker run -v sharedvol:/data container1docker run -v sharedvol:/data container2

Solution

1. Step 1: Create the named volume

   Use docker volume create sharedvol to make the volume first.

2. Step 2: Mount volume in both containers

   Use -v sharedvol:/data to mount the volume at /data inside each container.

3. Final Answer:

   docker volume create sharedvol
   docker run -v sharedvol:/data container1
   docker run -v sharedvol:/data container2 -> Option D

4. Quick Check:

   Named volume + mount path in both containers = sharing data [OK]

Hint: Create volume first, then mount with -v volume:path [OK]

Common Mistakes:

• Skipping volume creation step
• Reversing volume and path in -v option
• Omitting container path in volume mount