Docker Compose stdin_open

Introduction

stdin_open is a configuration option available in Docker Compose that allows a container to keep its STDIN file descriptor open. This means that the container can receive input data through STDIN and process it in real-time.

When stdin_open is set to true, Docker Compose assigns a TTY (terminal) to the container and connects it to the current session's STDIN. This gives the user the ability to interact with the container's command-line interface (CLI) and provide input data.

Syntax

The stdin_open option can be set in a Docker Compose file for a specific service as follows:

version: '3'
services:
  my_service:
    image: my_image
    stdin_open: true

Example

To demonstrate how stdin_open works, consider the following example where a user is prompted to enter their name, and then the container's CLI responds with a greeting that includes the user's name:

version: '3'
services:
  greet:
    image: my_image
    stdin_open: true
    tty: true
    command: sh -c "echo -n 'What is your name? '; read name; echo 'Hello, $name!'"

To run this example, save it as a file named docker-compose.yml and execute the following command in a terminal:

docker-compose up

This will start the greet service and prompt the user to enter their name. Once the user enters their name and presses enter, the container's CLI will respond with a greeting that includes the user's name.

Conclusion

The stdin_open configuration option in Docker Compose allows containers to keep their STDIN file descriptor open and receive input data through STDIN in real-time. This provides the ability to interact with the container's CLI and input data as needed.