Brooke  Giles

Brooke Giles


Setting Memory And CPU Limits In Docker

1. Overview

There are many cases in which we need to limit the usage of resources on the docker host machine.

In this tutorial, we’ll learn how to set the memory and CPU limit for docker containers.

2. Setting Resources Limit With docker run

We can set the resource limits directly using the docker run command. It’s a simple solution. However, the limit will apply only to one specific execution of the image.

2.1. Memory

For instance, let’s limit the memory that the container can use to 512 megabytes. To constrain memory, we need to use the m parameter:

$ docker run -m 512m nginx

We can also set a soft limit called a reservation. It’s activated when docker detects low memory on the host machine:

$ docker run -m 512m --memory-reservation=256m nginx

2.2. CPU

By default, access to the computing power of the host machine is unlimited. **We can set the CPUs limit using the cpus parameter. **For example, let’s constrain our container to use at most two CPUs:

$ docker run --cpus=2 nginx

We can also specify the priority of CPU allocation. The default is 1024, higher numbers are higher priority:

$ docker run --cpus=2 --cpu-shares=2000 nginx

Similarly to the memory reservation, CPU shares play the main role when computing power is scarce and needs to be divided between competing processes.

#docker #devops

What is GEEK

Buddha Community

Setting Memory And CPU Limits In Docker
Iliana  Welch

Iliana Welch


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

Docker Architecture Overview & Docker Components [For Beginners]

If you have recently come across the world of containers, it’s probably not a bad idea to understand the underlying elements that work together to offer containerisation benefits. But before that, there’s a question that you may ask. What problem do containers solve?

After building an application in a typical development lifecycle, the developer sends it to the tester for testing purposes. However, since the development and testing environments are different, the code fails to work.

Now, predominantly, there are two solutions to this – either you use a Virtual Machine or a containerised environment such as Docker. In the good old times, organisations used to deploy VMs for running multiple applications.

So, why did they started adopting containerisation over VMs? In this article, we will provide detailed explanations of all such questions.

#docker containers #docker engine #docker #docker architecture

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": {
                "": {
                        "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


Docker Tutorial for Beginners 8 - Build and Run C++ Applications in a Docker Container

Docker is an open platform that allows use package, develop, run, and ship software applications in different environments using containers.
In this course We will learn How to Write Dockerfiles, Working with the Docker Toolbox, How to Work with the Docker Machine, How to Use Docker Compose to fire up multiple containers, How to Work with Docker Kinematic, Push images to Docker Hub, Pull images from a Docker Registery, Push stacks of servers to Docker Hub.
How to install Docker on Mac.

#docker tutorial #c++ #docker container #docker #docker hub #devopstools

Alex Tyler

Alex Tyler


How to Set up Docker Registry and a Docker RegUI

In this story, we will install Docker Registry on a VM and the cloud and we will add a Docker container to browser the registries from a web browser. From my side, I created an ECS instance on Alibaba Cloud. But we could do it everywhere. After creating the ECS instance, I got its public IP address ( and I created a security group to authorize the following ports:

  • 5000 for the Docker Registry,
  • 8086 for the Docker Registry UI.

#docker #devops #docker-compose #docker-registry