Exploring Docker containers: Container Lifecycle

Exploring Docker containers: Container Lifecycle

Working with Docker containers involves managing the lifecycle of containers through various operations such as building images, pulling images, and running containers.

Below is an overview of the container lifecycle using Docker commands.

1. Docker Lifecycle: Building, Pulling, and Running Containers

1.1 Docker Build

Docker Build creates a container image from a Dockerfile.

Steps:

1. Create a Dockerfile specifying the base image, dependencies, and commands.

2. Use the docker build command to create an image from the Dockerfile.

Command:

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docker build -t my-image-name:tag .

Example:

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docker build -t my-app:latest .

1.2 Docker Pull

Docker Pull downloads an image from Docker Hub or other registries.

Steps:

Pull an image from Docker Hub or a private registry using the docker pull command.

Command:

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docker pull <image-name>:<tag>

Example:

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docker pull nginx:latest

1.3 Docker Run

Docker Run starts a container from a pulled or built image.

Steps:

1. Pull or build an image.

2. Start a container using the docker run command.

Command:

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docker run [OPTIONS] <image-name>:<tag>`

Example:

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docker run -p 8080:80 nginx:latest

2. Detailed Steps for Docker Build, Pull, and Run

2.1 Docker Build Process

1. Create Dockerfile:

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   FROM ubuntu:20.04`
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   RUN apt-get update && apt-get install -y curl`
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   COPY . /app`
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   WORKDIR /app`
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   CMD ["python", "app.py"]`
   

2. Build Image:

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   docker build -t my-app:latest .`
   

2.2 Docker Pull Process

Pull Image:

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docker pull alpine:3.15

2.3 Docker Run Process

Run Container:

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docker run -p 8080:80 my-app:latest

3. Docker Container Lifecycle

1. Docker Build

• Used to create a new container image.

• Specifies the steps Docker should follow to create the image.

2. Docker Pull

• Used to download pre-existing images from Docker Hub or private registries.

• Ensures the latest or a specific version of an image is used.

3. Docker Run

• Starts a new container from a specified image.

• Allows customization through various options such as ports, environment variables, volumes, and more.

4. Managing Containers

1. Stopping and Removing Containers

• Stop a container:

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  docker stop <container-id>
  

• Remove a container:

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  docker rm <container-id>
  

2. Listing Containers

• List Running Containers:

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  docker ps
  

• List All Containers:

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  docker ps -a
  

5. Using Docker Compose

Docker Compose simplifies the process of managing multi-container applications.

Example Docker Compose File (docker-compose.yml):

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version: '3'
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services:
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  web:
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    image: nginx:latest
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    ports:
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      - "80:80"
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    volumes:
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      - my-data-volume:/data
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volumes:
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  my-data-volume:

Using Docker Compose:

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docker-compose up --build

This builds, starts, and manages multi-container environments with ease.

Summary

By following these steps, you can effectively manage the lifecycle of Docker containers through building, pulling, and running.