eolas/zk/Docker_compose_and_Dockerfile_difference.md

---
id: fw56
tags:
  - docker
created: Tuesday, March 26, 2024
---

# Docker compose and Dockerfile difference

### Key Differences

- **Scope**: A `Dockerfile` is for building a single Docker image, while
  `docker-compose.yml` is for orchestrating multiple containers (that might be
  built from `Dockerfiles`) to work together as a unified application.
- **Use Case**: A `Dockerfile` is necessary when you need to create a custom
  image. In contrast, `docker-compose.yml` is used when you want to deploy and
  manage an application that consists of multiple containers.
- **Command**: You build an image from a `Dockerfile` using `docker build`. You
  start the application defined by `docker-compose.yml` using
  `docker-compose up`.

### Dockerfile

- **Purpose**: A `Dockerfile` is a text document that contains all the commands
  a user could call on the command line to assemble an image. It automates the
  process of creating Docker images by specifying a sequence of steps and
  configurations such as setting environment variables, installing software, and
  copying files from the local directory into the image.
- **Functionality**: It is essentially a blueprint for building Docker images.
  You define the base image, software packages, scripts, files, environment
  variables, and other components you need in your Docker image.
- **Usage**: You use a `Dockerfile` when you need to create a custom Docker
  image based on your application's specific dependencies and runtime
  environment. After defining your `Dockerfile`, you use the `docker build`
  command to create an image.

  Example structure of a Dockerfile:

  ```Dockerfile
  FROM python:3.8
  WORKDIR /app
  COPY . /app
  RUN pip install -r requirements.txt
  CMD ["python", "./my_script.py"]
  ```

### docker-compose.yml

- **Purpose**: A `docker-compose.yml` file is used to define and run
  multi-container Docker applications. With a single command, you can configure
  all of your application's services, networks, and volumes in this YAML file
  and bring everything up or down.
- **Functionality**: It simplifies the deployment and management of application
  components that are meant to run in separate containers while still needing to
  communicate or work together. For example, a web application might consist of
  a web server, a database, and a caching system, each running in its container.
- **Usage**: `docker-compose` is used for defining and running complex
  applications with Docker. Instead of using lengthy `docker run` commands with
  many flags, you write a `docker-compose.yml` file and use `docker-compose up`
  to start the application.

  Example structure of a docker-compose.yml file:

  ```yaml
  version: "3"
  services:
    web:
      build: .
      ports:
        - "5000:5000"
    db:
      image: postgres
      volumes:
        - ./data:/var/lib/postgresql/data
  ```