Sharing Data between Docker Containers (original) (raw)

Last Updated : 3 Sep, 2025

When you use Docker, each container runs separately, like its own small computer. This helps keep things organized and secure, but it can be a problem when containers need to work together. For example, if one container saves data (like a database) and another needs to use that data (like a web app), they need a way to share it. Without that, they can't talk to each other properly, and your app won’t run as it should.

Also, any data stored inside a container disappears when the container stops. So if you want to keep files, logs, or database records even after stopping or restarting, you need a way to store that data safely.

Methods of Sharing Data between Docker Containers

Below are 2 ways to share data between containers using Docker volumes and Bind Mount:

**Which One Should You Use?

Use **volumes for most cases, especially in production they're managed by Docker, portable, and ideal for sharing persistent data between containers. Use **bind mounts during **development when you need to sync files from your host, like live code changes. Volumes are more secure and stable; bind mounts offer more flexibility but are host-dependent.

The steps below will help you to share data using Docker Volumes:

Step 1: Create a Docker Volume

We can create a Docker Volume by using the following command

docker volume create shared-data

Step 2: Run Container A with the Volume

Mount the volume to a path inside Container A

docker run -d --name container-a -v shared-data:/data busybox sleep 3600

Here, /data is the path inside the container where the volume is mounted.

Step 3: Add Data in Container A

We are putting a message inside the volume folder from Container A. This file (message.txt) is saved in /data, which is the shared volume.

docker exec container-a sh -c "echo 'Hello from A' > /data/message.txt"

Step 4: Run Container B with the Same Volume

Now, you start Container B and connect it to the same volume. It will also see whatever is in /data, just like Container A.

docker run -d --name container-b -v shared-data:/data busybox sleep 3600

Step 5 : Access the Data in Container B

Inside Container B, you read the file message.txt. This shows the message written by Container A. That means sharing worked!

docker exec container-b cat /data/message.txt

This method is best for sharing host directories across containers. The following are the steps you can follow to share data using bind mounts:

Step 1: Create a Directory on the Host

Make a folder on your own computer (outside Docker) and save a file in it. This folder will be shared with containers.

mkdir /tmp/shared-dataecho "Hello from host" > /tmp/shared-data/host.txt

Step 2: Run Container A with Bind Mount

You start Container A and link it to your host folder. Inside the container, that folder will appear as /data.

docker run -d --name container-a -v /tmp/shared-data:/data busybox sleep 3600

Step 3: **Run Container B with Same Bind Mount

Now, Container B also connects to the same host folder. Both containers are now seeing the same /tmp/shared-data content.

docker run -d --name container-b -v /tmp/shared-data:/data busybox sleep 3600

Step 4: Check Shared File in Container B

Inside Container B, you check if it can read the file placed by the host. If you see the message, the data sharing worked.

docker exec container-b cat /data/host.txt

**Output: