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How do containers exchange data with each other?

DockerJunior~1 min read
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Containers exchange data mostly through the network that Docker creates between them. Usually this is done within a single virtual Docker network, where containers see each other by name, like a domain address.

1. Exchange through a Docker network (the main way)

  1. Create a network:
bash
docker network create mynet
  1. Run containers in it:
bash
docker run -d --name app --network=mynet myapp docker run -d --name db --network=mynet mydb

Now the app container can reach db by the name db (for example, mysql://db:3306).

Summary: safe network interaction within a single network.

2. Exchange through a shared volume

When files need to be passed (logs, data, cache):

bash
docker run -v shared:/data app1 docker run -v shared:/data app2

Both containers use the same storage point.

Summary: shared access to files.

3. Exchange through external services

Containers can interact through:

  • a database,
  • a message queue (Kafka, RabbitMQ),
  • HTTP/REST API requests.

Summary: a scalable approach, common in microservices.

Summary for a junior

Containers exchange data through a network (most often), a shared volume (for files), or external services. The most common path is a Docker network, where containers see each other by name.

If needed, I can explain the same thing in the next message and show how this looks in docker-compose, where the connection between containers is fully automatic.

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