Volume vs bind mount decision in Docker - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a Docker volume named 'data_vol'.

Docker

docker volume [1] data_vol

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

Arun

Bbuild

Ccreate

Dstart

Attempts:

3 left

💡 Hint

Common Mistakes

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

The docker volume create command creates a new volume named 'data_vol'.

2fill in blank

medium

Complete the code to run a container with a bind mount from host directory '/host/data' to container '/app/data'.

Docker

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

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

A/host/data

B/data

C/app/data

D/container/data

Attempts:

3 left

💡 Hint

Common Mistakes

Using container path as source instead of host path.

The bind mount source is the host directory /host/data, which is mounted to /app/data inside the container.

3fill in blank

hard

Fix the error in the command to mount a volume named 'myvol' to '/data' in the container.

Docker

docker run -v [1]:/data myimage

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

Amyvol_data

Bmyvol:/data

Cvolume:myvol

Dmyvol

Attempts:

3 left

💡 Hint

Common Mistakes

Adding extra text like ':myvol' or including the container path twice.

When mounting a named volume, only the volume name is given before the colon. The correct syntax is -v myvol:/data. Option D provides just the volume name for the source.

4fill in blank

hard

Fill all three blanks to create a bind mount from host directory '/var/log' to container directory '/logs' with read-only access.

Docker

docker run -v [1]:[2]:[3] myimage

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

A/var/log

B/logs

Cro

Drw

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'rw' instead of 'ro' for read-only mounts.

The bind mount source is /var/log on the host, mounted to /logs in the container with ro (read-only) access.

5fill in blank

hard

Fill all three blanks to create a volume mount with a named volume 'cache_vol', mounted to '/cache' in the container with read-write access.

Docker

docker run -v [1]:[2]:[3] myimage

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

Acache_vol

B/cache

Crw

Dro

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'ro' instead of 'rw' for read-write mounts.

The named volume cache_vol is mounted to /cache inside the container with rw (read-write) access.

Practice

1. Which Docker storage option should you use if you want Docker to manage persistent data independently of the host system?

easy

A. Use a temporary container filesystem

B. Use a bind mount

C. Use a network file share

D. Use a Docker volume

Solution

1. Step 1: Understand Docker volume purpose

   Docker volumes are designed to store persistent data managed by Docker itself, independent of the host's file system structure.

2. Step 2: Compare with bind mounts

   Bind mounts link host files or folders directly, so Docker does not manage the data lifecycle.

3. Final Answer:

   Use a Docker volume -> Option D

4. Quick Check:

   Docker manages data = Use volume [OK]

Hint: Docker manages data? Choose volume. Host controls? Choose bind mount. [OK]

Common Mistakes:

• Confusing bind mounts as Docker-managed storage
• Using temporary container filesystem for persistent data
• Assuming network file share is a Docker volume

2. Which of the following is the correct syntax to create a Docker container with a bind mount from host folder /home/user/data to container folder /app/data?

easy

A. docker run -v /home/user/data:/app/data myimage

B. docker run --mount type=bind,source=/app/data,target=/home/user/data myimage

C. docker run --bind /home/user/data:/app/data myimage

D. docker run -v /app/data:/home/user/data myimage

Solution

1. Step 1: Recall bind mount syntax with -v

   The correct syntax for bind mounts with -v is -v host_path:container_path. So -v /home/user/data:/app/data is correct.

2. Step 2: Check other options for errors

   docker run --mount type=bind,source=/app/data,target=/home/user/data myimage reverses source and target paths and uses --mount incorrectly. docker run --bind /home/user/data:/app/data myimage uses invalid flag --bind. docker run -v /app/data:/home/user/data myimage reverses host and container paths.

3. Final Answer:

   docker run -v /home/user/data:/app/data myimage -> Option A

4. Quick Check:

   Bind mount syntax = -v host:container [OK]

Hint: Bind mount syntax: -v host_path:container_path [OK]

Common Mistakes:

• Reversing host and container paths
• Using invalid flags like --bind
• Confusing --mount syntax parameters

3. Given the command docker run -v mydata:/data busybox ls /data, what will be the output if mydata volume is empty?

medium

A. Lists files from host /data directory

B. Shows an empty list (no files)

C. Throws an error: volume not found

D. Lists files from busybox image /data directory

Solution

1. Step 1: Understand volume behavior

   The volume mydata is mounted at /data inside the container. If the volume is empty, the container sees an empty directory at /data.

2. Step 2: Check command output

   The ls /data command lists files in the mounted volume. Since it is empty, the output is empty (no files listed).

3. Final Answer:

   Shows an empty list (no files) -> Option B

4. Quick Check:

   Empty volume = empty directory inside container [OK]

Hint: Empty volume means empty folder inside container [OK]

Common Mistakes:

• Assuming volume auto-fills with image files
• Expecting error if volume is empty
• Confusing volume with bind mount behavior

4. You want to edit source code files live on your host and see changes immediately inside the container. You tried docker run -v /app/src busybox but it fails. What is the error and how to fix it?

medium

A. Error: permission denied; fix by running as root

B. Error: volume not found; fix by creating volume first

C. Error: missing container path; fix by adding host:container in -v

D. Error: invalid image; fix by using correct image name

Solution

1. Step 1: Identify syntax error in -v flag

   The command -v /app/src is incomplete. Docker expects -v host_path:container_path or volume_name:container_path.

2. Step 2: Fix by specifying both paths

   To bind mount host folder /app/src into container, use -v /app/src:/app/src or similar.

3. Final Answer:

   Error: missing container path; fix by adding host:container in -v -> Option C

4. Quick Check:

   -v requires host:container paths [OK]

Hint: -v must have host and container paths separated by colon [OK]

Common Mistakes:

• Using only one path in -v flag
• Confusing volume creation with bind mount syntax
• Ignoring error messages about syntax

5. You want to share a configuration file /etc/config.yaml from your host with multiple containers, and you want Docker to manage the data lifecycle. Which approach is best?

hard

A. Create a Docker volume, copy the file into it, then mount the volume in containers

B. Use a bind mount directly from /etc/config.yaml to containers

C. Copy the file into each container image manually

D. Use a network file share mounted inside containers

Solution

1. Step 1: Understand requirement for Docker-managed data

   You want Docker to manage the data lifecycle, so bind mounts (host-managed) are not ideal.

2. Step 2: Use volume and copy file

   Create a Docker volume, copy /etc/config.yaml into it once, then mount this volume into all containers. This centralizes management.

3. Final Answer:

   Create a Docker volume, copy the file into it, then mount the volume in containers -> Option A

4. Quick Check:

   Docker manages data = use volume + copy file [OK]

Hint: For Docker-managed shared data, use volume with copied files [OK]

Common Mistakes:

• Using bind mounts when Docker management is needed
• Copying files into images instead of using volumes
• Assuming network shares are Docker volumes