Compose watch for development in Docker - Step-by-Step Execution

Process Flow - Compose watch for development

Start docker compose watch

↓

Run service containers

↓

Watch source files for changes

↓

Detect file change?

No→Keep running

Yes↓

Restart affected containers

↓

Continue watching

Docker Compose starts containers, watches source files, and restarts containers automatically when files change.

Execution Sample

Docker

version: '3.8'
services:
  app:
    build: .
    volumes:
      - .:/app
    command: sh -c "while true; do sleep 1; done"

This docker-compose.yml is used with `docker compose watch`. It runs a container with the current folder mounted into /app, keeping it alive with a sleep loop while watch handles restarts on changes.

Process Table

Step	Action	File Change Detected	Container State	Output
1	Start docker compose watch	No	Container starting	Building image and starting container
2	Container running	No	Container running	App running, waiting for changes
3	File changed in source folder	Yes	Container restarting	Stopping container and restarting
4	Container restarted	No	Container running	Container restarted with new code
5	No further changes	No	Container running	Waiting for changes
6	User stops docker compose watch	No	Container stopped	Containers stopped and removed

💡 User stops docker compose watch, ending watch and container lifecycle

Status Tracker

Variable	Start	After Step 2	After Step 3	After Step 4	Final
Container State	Not running	Running	Restarting	Running	Stopped
File Change Detected	No	No	Yes	No	No

Key Moments - 2 Insights

Why does the container restart when a file changes?

Because docker-compose watch detects the file change (see Step 3 in execution_table) and triggers a container restart to apply updates.

What keeps the container running when no file changes happen?

The container runs a command that keeps it alive (like a sleep loop), so it stays running waiting for changes (see Step 2).

Visual Quiz - 3 Questions

Look at the execution table, what is the container state at Step 3?

A Running

B Stopped

C Restarting

D Starting

💡 Hint

Check the 'Container State' column at Step 3 in the execution_table.

At which step does the container restart due to file changes?

A Step 3

B Step 5

C Step 2

D Step 6

💡 Hint

Look for 'File Change Detected' marked 'Yes' in the execution_table.

If no file changes occur, what will the container state be after Step 2?

A Restarting

B Running

C Stopped

D Starting

💡 Hint

Refer to 'Container State' at Step 2 in the execution_table.

Concept Snapshot

Docker Compose watch runs containers and monitors source files.
When files change, it restarts containers to update code.
Use volumes to mount source code for live updates.
Keep containers alive with a command like a sleep loop.
Stop with Ctrl+C to end watching and containers.

Full Transcript

Docker Compose watch for development means running your app in containers that automatically restart when you change your code files. First, docker compose watch starts your containers and mounts your source code folder inside them. The containers run a command that keeps them alive, waiting for changes. When you edit a file, docker compose watch detects this change and restarts the affected containers so your app updates with the new code. If no changes happen, the containers keep running. When you want to stop, you press Ctrl+C, and docker compose watch stops and removes the containers. This process helps developers see their code changes live without manually restarting containers.