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zk/Docker_compose_and_Dockerfile_difference.md

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+---
+id: fw56
+title: Docker compose and Dockerfile difference
+tags: []
+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
+  ```