76 lines
2.8 KiB
Markdown
76 lines
2.8 KiB
Markdown
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---
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id: fw56
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tags:
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- docker
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created: Tuesday, March 26, 2024
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---
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# Docker compose and Dockerfile difference
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### Key Differences
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- **Scope**: A `Dockerfile` is for building a single Docker image, while
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`docker-compose.yml` is for orchestrating multiple containers (that might be
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built from `Dockerfiles`) to work together as a unified application.
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- **Use Case**: A `Dockerfile` is necessary when you need to create a custom
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image. In contrast, `docker-compose.yml` is used when you want to deploy and
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manage an application that consists of multiple containers.
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- **Command**: You build an image from a `Dockerfile` using `docker build`. You
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start the application defined by `docker-compose.yml` using
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`docker-compose up`.
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### Dockerfile
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- **Purpose**: A `Dockerfile` is a text document that contains all the commands
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a user could call on the command line to assemble an image. It automates the
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process of creating Docker images by specifying a sequence of steps and
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configurations such as setting environment variables, installing software, and
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copying files from the local directory into the image.
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- **Functionality**: It is essentially a blueprint for building Docker images.
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You define the base image, software packages, scripts, files, environment
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variables, and other components you need in your Docker image.
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- **Usage**: You use a `Dockerfile` when you need to create a custom Docker
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image based on your application's specific dependencies and runtime
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environment. After defining your `Dockerfile`, you use the `docker build`
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command to create an image.
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Example structure of a Dockerfile:
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```Dockerfile
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FROM python:3.8
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WORKDIR /app
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COPY . /app
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RUN pip install -r requirements.txt
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CMD ["python", "./my_script.py"]
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```
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### docker-compose.yml
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- **Purpose**: A `docker-compose.yml` file is used to define and run
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multi-container Docker applications. With a single command, you can configure
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all of your application's services, networks, and volumes in this YAML file
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and bring everything up or down.
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- **Functionality**: It simplifies the deployment and management of application
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components that are meant to run in separate containers while still needing to
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communicate or work together. For example, a web application might consist of
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a web server, a database, and a caching system, each running in its container.
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- **Usage**: `docker-compose` is used for defining and running complex
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applications with Docker. Instead of using lengthy `docker run` commands with
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many flags, you write a `docker-compose.yml` file and use `docker-compose up`
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to start the application.
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Example structure of a docker-compose.yml file:
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```yaml
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version: "3"
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services:
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web:
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build: .
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ports:
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- "5000:5000"
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db:
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image: postgres
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volumes:
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- ./data:/var/lib/postgresql/data
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```
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