Named volumes for data sharing in Docker - Step-by-Step Execution

Process Flow - Named volumes for data sharing

Create Named Volume

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Start Container A

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Container A writes data

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Start Container B

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Container B reads data

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Data shared via Named Volume

This flow shows how a named volume is created and used by two containers to share data persistently.

Execution Sample

Docker

docker volume create shared_data

docker run -d --name containerA -v shared_data:/data busybox sh -c "echo hello > /data/greeting.txt && sleep 3600"

docker run --rm -v shared_data:/data busybox cat /data/greeting.txt

Create a named volume, write data in one container, then read it from another container.

Process Table

Step	Action	Command	Result/Output
1	Create named volume	docker volume create shared_data	Volume 'shared_data' created
2	Start containerA with volume	docker run -d --name containerA -v shared_data:/data busybox sh -c "echo hello > /data/greeting.txt && sleep 3600"	Container 'containerA' running, file /data/greeting.txt created with 'hello'
3	Start containerB to read data	docker run --rm -v shared_data:/data busybox cat /data/greeting.txt	Output: hello
4	Stop containerA	docker stop containerA	Container 'containerA' stopped
5	Remove containerA	docker rm containerA	Container 'containerA' removed

💡 Data persists in named volume 'shared_data' even after containerA is removed

Status Tracker

Variable	Initial	After Step 1	After Step 2	After Step 3	Final
shared_data volume	none	created	contains greeting.txt with 'hello'	accessible with 'hello' content	persists with data intact

Key Moments - 2 Insights

Why does containerB see the file created by containerA?

Because both containers use the same named volume 'shared_data' mounted at /data, so data written by containerA is accessible to containerB as shown in execution_table step 3.

What happens to the data if containerA is removed?

The data remains in the named volume 'shared_data' even after containerA is removed, as shown in execution_table step 5 and variable_tracker final state.

Visual Quiz - 3 Questions

Look at the execution table, what is the output when containerB reads the file?

A empty output

B hello

C error: file not found

D containerB fails to start

💡 Hint

Check execution_table row 3 under Result/Output

At which step is the named volume created?

A Step 3

B Step 2

C Step 1

D Step 4

💡 Hint

Look at execution_table row 1 Action and Command

If containerA did not write the file, what would containerB see when reading?

A error: file not found

B hello

C empty output

D containerB crashes

💡 Hint

Think about what happens if the file /data/greeting.txt does not exist in the volume

Concept Snapshot

Named volumes in Docker allow data sharing between containers.
Create a volume with 'docker volume create NAME'.
Mount it with '-v NAME:/path' in containers.
Data persists beyond container life.
Containers share files via the volume path.

Full Transcript

This visual execution shows how Docker named volumes enable data sharing between containers. First, a named volume 'shared_data' is created. Then containerA starts with this volume mounted at /data and writes a file greeting.txt with content 'hello'. Next, containerB starts with the same volume mounted and reads the file, outputting 'hello'. Even after containerA stops and is removed, the data remains in the named volume. This demonstrates persistent and shared storage using Docker named volumes.