Step-by-Step Container Management

Welcome back to your Docker learning journey. In the previous lesson, you explored the docker run command, enabling you to create and start a container in a single step. However, this command encapsulates multiple underlying processes that control various aspects of container lifecycle management. Now, it's time to delve deeper into the intricacies of these processes by breaking them down into separate commands.

Introduction to Docker Hub

Before we begin pulling external images, it's helpful to know about Docker Hub. As the main source for Docker images, Docker Hub simplifies accessing a wide variety of software without needing to build images yourself. Docker Hub is an online platform where you can find, download, and share Docker images. It acts as a centralized repository, making it easy to use various software without building images from scratch. You can search for and pull images for web servers, databases, and thousands of other applications, ranging from simple utilities to complex computing frameworks, covering a vast array of needs and uses. Popular images on Docker Hub include: Nginx : A widely-used web server. MySQL : A popular database management system. Redis : An in-memory data store often used for caching. Node.js : A JavaScript runtime for building applications. Ubuntu : A base image for Linux operating systems. In addition to using pre-built images, Docker Hub allows you to push your own images and share them with others, facilitating collaboration and distribution of your applications.

Understanding the Run Command

As mentioned before, the docker run command allows you to create and start a container in one seamless step. While efficient, this command encompasses several underlying processes: First, it checks if the specified image is available locally. If not, it pulls the image from Docker Hub or another registry. Then, it creates a container based on the downloaded image. Finally, it starts the created container immediately. By breaking these steps into separate commands, namely pull, create, and start, you can gain a more thorough understanding and finer control over these processes. This approach lays the groundwork for more advanced container management techniques.

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Shell

# Pulling an external Docker image from Docker Hub
docker pull nginx

# Pulling an external Docker image from Docker Hub
docker pull nginx

text

Using default tag: latest
latest: Pulling from library/nginx
302e3ee49805: Pull complete 
d07412f52e9d: Pull complete 
9ab66c386e9c: Pull complete 
4b563e5e980a: Pull complete 
55af3c8febf2: Pull complete 
5b8e768fb22d: Pull complete 
85177e2c6f39: Pull complete 
Digest: sha256:d2eb56950b84efe34f966a2b92efb1a1a2ea53e7e93b94cdf45a27cf3cd47fc0
Status: Downloaded newer image for nginx:latest
docker.io/library/nginx:latest

Using default tag: latest
latest: Pulling from library/nginx
302e3ee49805: Pull complete 
d07412f52e9d: Pull complete 
9ab66c386e9c: Pull complete 
4b563e5e980a: Pull complete 
55af3c8febf2: Pull complete 
5b8e768fb22d: Pull complete 
85177e2c6f39: Pull complete 
Digest: sha256:d2eb56950b84efe34f966a2b92efb1a1a2ea53e7e93b94cdf45a27cf3cd47fc0
Status: Downloaded newer image for nginx:latest
docker.io/library/nginx:latest

Shell

# 1. Creating a container without specifying a name
docker create nginx

# 2. Creating a container with a custom name
docker create --name my-nginx nginx

# 1. Creating a container without specifying a name
docker create nginx

# 2. Creating a container with a custom name
docker create --name my-nginx nginx

text

c49adf897b2a74bcbed915a76eea458b19eae8afa4a71e9b007eb9dbb3723c89

c49adf897b2a74bcbed915a76eea458b19eae8afa4a71e9b007eb9dbb3723c89

text

CONTAINER ID   IMAGE     COMMAND                  CREATED         STATUS    PORTS     NAMES
c49adf897b2a   nginx     "/docker-entrypoint.…"   3 minutes ago   Created             my-nginx

CONTAINER ID   IMAGE     COMMAND                  CREATED         STATUS    PORTS     NAMES
c49adf897b2a   nginx     "/docker-entrypoint.…"   3 minutes ago   Created             my-nginx

Shell

# Option 1: Start the container using the name
docker start my_nginx
# Output: my_nginx

# Option 2: Start the container using the container ID
docker start c49adf897b2a
# Output: c49adf897b2a

# Option 1: Start the container using the name
docker start my_nginx
# Output: my_nginx

# Option 2: Start the container using the container ID
docker start c49adf897b2a
# Output: c49adf897b2a

text

CONTAINER ID   IMAGE     COMMAND                  CREATED          STATUS         PORTS     NAMES
c49adf897b2a   nginx     "/docker-entrypoint.…"   11 minutes ago   Up 9 seconds   80/tcp    my-nginx

CONTAINER ID   IMAGE     COMMAND                  CREATED          STATUS         PORTS     NAMES
c49adf897b2a   nginx     "/docker-entrypoint.…"   11 minutes ago   Up 9 seconds   80/tcp    my-nginx

Shell

# Option 1: Stop the container using the name
docker stop my-nginx
# Output: my-nginx

# Option 1: Stop the container using the container ID
docker stop c49adf897b2a
# Output: c49adf897b2a

# Option 1: Stop the container using the name
docker stop my-nginx
# Output: my-nginx

# Option 1: Stop the container using the container ID
docker stop c49adf897b2a
# Output: c49adf897b2a

text

CONTAINER ID   IMAGE     COMMAND                  CREATED       STATUS                     PORTS     NAMES
c49adf897b2a   nginx     "/docker-entrypoint.…"   2 hours ago   Exited (0) 5 seconds ago             my-nginx

CONTAINER ID   IMAGE     COMMAND                  CREATED       STATUS                     PORTS     NAMES
c49adf897b2a   nginx     "/docker-entrypoint.…"   2 hours ago   Exited (0) 5 seconds ago             my-nginx

Shell

# Pulling an external Docker image from Docker Hub
docker pull nginx

text

Using default tag: latest
latest: Pulling from library/nginx
302e3ee49805: Pull complete 
d07412f52e9d: Pull complete 
9ab66c386e9c: Pull complete 
4b563e5e980a: Pull complete 
55af3c8febf2: Pull complete 
5b8e768fb22d: Pull complete 
85177e2c6f39: Pull complete 
Digest: sha256:d2eb56950b84efe34f966a2b92efb1a1a2ea53e7e93b94cdf45a27cf3cd47fc0
Status: Downloaded newer image for nginx:latest
docker.io/library/nginx:latest

Shell

# 1. Creating a container without specifying a name
docker create nginx

# 2. Creating a container with a custom name
docker create --name my-nginx nginx

text

c49adf897b2a74bcbed915a76eea458b19eae8afa4a71e9b007eb9dbb3723c89

text

CONTAINER ID   IMAGE     COMMAND                  CREATED         STATUS    PORTS     NAMES
c49adf897b2a   nginx     "/docker-entrypoint.…"   3 minutes ago   Created             my-nginx

Shell

# Option 1: Start the container using the name
docker start my_nginx
# Output: my_nginx

# Option 2: Start the container using the container ID
docker start c49adf897b2a
# Output: c49adf897b2a

text

CONTAINER ID   IMAGE     COMMAND                  CREATED          STATUS         PORTS     NAMES
c49adf897b2a   nginx     "/docker-entrypoint.…"   11 minutes ago   Up 9 seconds   80/tcp    my-nginx

Shell

# Option 1: Stop the container using the name
docker stop my-nginx
# Output: my-nginx

# Option 1: Stop the container using the container ID
docker stop c49adf897b2a
# Output: c49adf897b2a

text

CONTAINER ID   IMAGE     COMMAND                  CREATED       STATUS                     PORTS     NAMES
c49adf897b2a   nginx     "/docker-entrypoint.…"   2 hours ago   Exited (0) 5 seconds ago             my-nginx

Step-by-Step Container Management

Introduction to Docker Hub

Understanding the Run Command

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Pulling an External Docker Image

Creating a Container

Checking the Container Status: Created

Starting a Container

Checking the Container Status: Up

Stopping a Running Container

Checking the Container Status: Exited

Summary and Practice Preparation