Removing Docker Images

1. Introduction

In a previous article, we explained the difference between Docker images and Docker containers. In short: An image is like a Java class, and containers are like Java objects.

In this tutorial, we’ll look at the various ways of removing Docker images.

2. Why Remove Docker Images?

The Docker Engine stores images and runs containers. For that purpose, the Docker Engine reserves a certain amount of disk space as a “storage pool” for images, containers, and everything else (such as global Docker volumes or networks).

Once that storage pool is full, the Docker Engine stops working: We can’t create or download new images anymore, and our containers fail to run.

Docker images take up the majority of the Docker Engine storage pool. So we remove Docker images to keep Docker running.

We also remove images to keep our Docker Engine organized and clean. For instance, we can easily create dozens of images during development that we soon don’t need anymore. Or, we download some software images for testing that we can dispose of later.

We can easily remove a Docker image that we pulled from a Docker repository: If we ever need it again, we’ll just pull it from the repository once more.

But we have to be careful with Docker Images we created ourselves: **Once removed, our own images are gone unless we saved them! **We can save Docker images by pushing them to a repository or exporting them to a TAR file.

3. Downloading PostgreSQL 13 Beta Images

PostgreSQL is an open-source relational database. We’ll use the first two PostgreSQL 13 beta Docker images as examples. These two images are relatively small, so we can download them quickly. And because they are beta software, we don’t have them in our Docker Engine already.

We’ll use the beta 2 image to create a container. We won’t use the beta 1 image directly.

But before we download these two images, let’s check first how much space Docker images take up in the storage pool:

#devops #docker #docker images #docker containers

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Buddha Community

Removing Docker Images

Docker manifest - A peek into image's manifest.json files

docker manifest – An experimental feature !

The image manifest provides a configuration and a set of layers for a container image.

This is an experimental feature. To enable this feature in the Docker CLI, one can edit the config.json file found in ~/.docker/config.json like :

{
        "auths": {
                "https://index.docker.io/v1/": {
                        "auth": "XXXXXXX"
                }
        },
        "HttpHeaders": {
                "User-Agent": "Docker-Client/19.03.8 (linux)"
        },
        "experimental": "enabled",
        "debug": true
}

What is ‘docker manifest’ ?

The docker manifest command does not work independently to perform any action. In order to work with the docker manifest or manifest list, we use sub-commands along with it. This manifest sub-command can enable us to interact with the image manifests. Furthermore, it also gives information about the OS and the architecture, that a particular image was built for.

A single manifest comprises of information about an image, it’s size, the layers and digest.

A manifest list is a list of image layers (manifests) that are, created by specifying one or more image names. It can then be used in the same way as an image name in docker pull and docker run commands.

Commands to get started with :

After enabling this feature, one would be able to access the following command :

docker-manifest-enter image description here

These commands are easy to use. It basically avoids the need for pulling and running and then testing the images locally, from a docker registry.

Next, to inspect an image manifest, follow this syntax,

 docker manifest inspect image-name

enter image description here

.

#devops #docker #devops #docker #docker learning #docker-image

Iliana  Welch

Iliana Welch

1595249460

Docker Explained: Docker Architecture | Docker Registries

Following the second video about Docker basics, in this video, I explain Docker architecture and explain the different building blocks of the docker engine; docker client, API, Docker Daemon. I also explain what a docker registry is and I finish the video with a demo explaining and illustrating how to use Docker hub

In this video lesson you will learn:

  • What is Docker Host
  • What is Docker Engine
  • Learn about Docker Architecture
  • Learn about Docker client and Docker Daemon
  • Docker Hub and Registries
  • Simple demo to understand using images from registries

#docker #docker hub #docker host #docker engine #docker architecture #api

Removing Docker Images

1. Introduction

In a previous article, we explained the difference between Docker images and Docker containers. In short: An image is like a Java class, and containers are like Java objects.

In this tutorial, we’ll look at the various ways of removing Docker images.

2. Why Remove Docker Images?

The Docker Engine stores images and runs containers. For that purpose, the Docker Engine reserves a certain amount of disk space as a “storage pool” for images, containers, and everything else (such as global Docker volumes or networks).

Once that storage pool is full, the Docker Engine stops working: We can’t create or download new images anymore, and our containers fail to run.

Docker images take up the majority of the Docker Engine storage pool. So we remove Docker images to keep Docker running.

We also remove images to keep our Docker Engine organized and clean. For instance, we can easily create dozens of images during development that we soon don’t need anymore. Or, we download some software images for testing that we can dispose of later.

We can easily remove a Docker image that we pulled from a Docker repository: If we ever need it again, we’ll just pull it from the repository once more.

But we have to be careful with Docker Images we created ourselves: **Once removed, our own images are gone unless we saved them! **We can save Docker images by pushing them to a repository or exporting them to a TAR file.

3. Downloading PostgreSQL 13 Beta Images

PostgreSQL is an open-source relational database. We’ll use the first two PostgreSQL 13 beta Docker images as examples. These two images are relatively small, so we can download them quickly. And because they are beta software, we don’t have them in our Docker Engine already.

We’ll use the beta 2 image to create a container. We won’t use the beta 1 image directly.

But before we download these two images, let’s check first how much space Docker images take up in the storage pool:

#devops #docker #docker images #docker containers

Docker creating an image | Build and run your image | Docker Fundamentals

Docker create an image from a container | Creating your own image | How to create Docker Image from a Container and Dockerfile.

#docker #image #dockers

August  Murray

August Murray

1615008840

Top 24 Docker Commands Explained with Examples

In my previous blog post, I have explained in detail how you can Install Docker and Docker-compose on Ubuntu

In this guide, I have explained the Top 24 Docker Commands with examples.

Make sure you have sudo or root privileges to the system.

Docker Commands

  1. The command to check the version of Docker installed.
  2. To look/search for available docker images from the Docker registry.
  3. To pull docker images from the Docker registry.
  4. Listing all the docker images
  5. Creating / Running docker container from Docker image.
  6. To list the actively running docker containers.
  7. To list all the docker containers
  8. To stop a Container
  9. To start a Container
  10. To restart a Docker container
  11. To login to running Docker container
  12. To delete the stopped Docker containers
  13. To delete Docker images from the Local system
  14. To check logs of a running Docker container
  15. Killing docker containers
  16. Log in to Docker Hub registry (hub.docker.com)
  17. Removing docker hub registry login from the system.
  18. Check active resource usage by each containers
  19. Rename a Docker container
  20. To display system wide information of Docker
  21. Inspecting a Docker container
  22. Building docker images from Docker file
  23. Creating new docker images from a Container
  24. Pushing Docker images from Local to Docker registry.

#docker #docker-command #containers #docker-compose #docker-image