Category Archives for "Docker Blog"

Awesome-Compose: Application samples for project development kickoff

Software systems have become quite complex nowadays. A system may consist of several distributed services, each one providing a specific functionality and being updated independently. Starting the development of a project of such complexity is sometimes time consuming, in particular when you are not already familiar with the software stack you are going to work on. This may be because, most of the time, we need to follow rigorous steps to put together the entire project and if we make a mistake in-between, we may have to start all over again.

As a developer, getting a quick understanding of how all the stack is wired together and having an easy to manage project skeleton may be a very good incentive to use that particular stack for future projects. 

Furthermore, there are plenty of open-source software stacks that developers can use for their own setups. Providing them with a straightforward way to deploy these software stacks in order to check them out is an important matter when looking to simplify software development and allow developers to explore different options. 

To tackle this, we have put together a Github repository with application samples that can be easily deployed with Docker Continue reading

#myDockerBday Discounts on Docker Captain Docker + Kubernetes Content

If your #myDockerBday celebration included wanting to learn more about Docker or Kubernetes, you are in luck. In honor of Docker’s 7th birthday, Docker Captains have extended some fantastic deals on their learning content. Take this opportunity to level up your skills and learn Docker with excellent instructors. 

Books and EBooks

Through the end of March, you can get Elton Stoneman’s Learn Docker in a Month of Lunches and/or Jeff Nickeloff’s Docker in Action 2nd Edition for 40% off using the code mtpdocker20.

Learn Docker in a Month of Lunches

Elton Stoneman
Go from zero to production readiness with Docker in 22 bite-sized lessons! Learn Docker in a Month of Lunches is an accessible task-focused guide to Docker on Linux, Windows, or Mac systems. In it, you’ll learn practical Docker skills to help you tackle the challenges of modern IT, from cloud migration and microservices to handling legacy systems. There’s no excessive theory or niche-use cases– just a quick-and-easy guide to the essentials of Docker you’ll use every day.

Docker in Action 2nd Edition

Jeff Nickeloff
Docker in Action, Second Edition teaches you the skills and knowledge you need to create, deploy, and manage applications hosted in Docker containers. Continue reading

First Docker GitHub Action is here!

We are happy to announce that today Docker has released its first Github Action! We’ve been working with GitHub, looking into how developers have been using GitHub Actions with Docker to set up their CI/CD workflows. The standard flows you’ll see if you look around are what you’d expect: building an image, tagging it, logging into Hub, and pushing the image. This is the workflow we’ve aimed to support with our Docker build-push action.

Simplify CI/CD workflows

At Docker traditionally much of our CI/CD workflows has been handled through Jenkins using a variety of products to set up and maintain it. For some things this is the best solution like when we are testing Docker Desktop on a whole variety of different hosts and configurations. For others it’s a bit overkill. Like many, we at Docker have been looking at how we can leverage GitHub Actions to simplify our workflows, including how we use Docker itself.

GitHub Actions already leverages Docker in a lot of its workflows. From having Docker pre-installed and configured on the cloud runners to having first class support for containerized actions allows developers to easily use the same Docker workflows they use locally to configure Continue reading

DockerCon LIVE with theCUBE: Call for Papers is Open

CFP Deadline: March 27th at 11:59 PM PST

The beauty of Docker is in the ways that developers are using it to positively impact their lives, industries, and day-to-day workflows. From sending rockets to space, to running some of the biggest apps on Earth, Docker helps developers build and share containerized apps – from the boring to the apps that change the world. DockerCon is the place where the community comes together to connect and share stories, best practices, and use cases. 

Back in December, we announced that DockerCon would not be a physical event but instead was evolving into a digital event. At the time, that decision was made in order to make attending DockerCon an option for any and all developers and members of the community. And now with the current state of the global COVID-19 pandemic, we are extra thankful to have already been planning for a virtual-only gathering. This change to DockerCon is the safest and healthiest option for our community, and we are excited to still bring everyone together to learn and share from one another.  

This year, DockerCon will be a virtual event on May 28th from 9am to 5pm GMT -8. Continue reading

Docker Turns 7!

Since its introduction at PyCon in 2013, Docker has changed the way the world develops applications. And over the last 7 years, we’ve loved watching developers – new and seasoned – bring their ideas to life with Docker.

As is our tradition in the Docker community, we will be celebrating Docker’s birthday month with meetups (virtual + IRL), a special hands-on challenge, cake, and swag. Join us and celebrate your #myDockerBDay and the ways Docker and this community have impacted you – from the industry you work in, to an application you’ve built; from your-day-to-day workflow to your career. 

Learn more about the birthday celebrations below and share your #myDockerBday story with us on twitter or submit it here for a chance to win some awesome Docker swag.

Docker Birthday LIVE Show on March 26th, 9am – 12pm GMT-8

Celebrate Docker’s Birthday with a special 3-hour live show featuring exclusive conversations with the Docker team and Captains, open Q&A sessions, and prizes. To reserve a spot, sign up here

7th Birthday Challenge

Learn some of the Docker Captain’s favorite Tips + Tricks by completing 7 hands-on exercises. Earn a virtual badge for each exercise completed.

Learn Docker with Continue reading

Helping You and Your Development Team Build and Ship Faster

I remember the first time one of my co-workers told me about Docker. There is a longer story behind it, but it ended with “it was so easy and saved me so much time.” That compelled me to install Docker and try it for myself. Yup, she was right. Easy, simple, efficient. Sometime later, at a conference, while catching up with some friends who are developers, I asked them “how are things going?” The conversation eventually led to the topic of where things are going in the container space. I asked, “what’s the biggest issue you are having right now?” I expected the response to be something Kubernetes related. I was surprised the answer was “managing all the tech that gets my code deployed and running.” 

The above sentiment is echoed by our CEO, Scott Johnston, in this post. Millions of you use Docker today (check out the Docker Index for the latest usage stats), and we are so very thankful for the vibrant Docker Community. We heard from you that easily going from code to cloud is a problem, and Scott outlined the complexities. There are many choices across packaging, inner loop, packaging, registry, Continue reading

Helping Developers Simplify Apps, Toolchains, and Open Source

It’s been an exciting four months since we announced that Docker is refocusing on developers. We have spent much of that time listening to you, our developer community, in meetups, on GitHub, through social media, with our Docker Captains, and in face-to-face one-on-ones. Your support and feedback on our refocused direction have been helpful and positive, and we’re fired-up for the year ahead!

What’s driving our enthusiasm for making developers successful? Quite simply, it’s in recognition of the enormous impact your creativity – manifested in the applications you ship – has on all of our lives. Widespread adoption of smartphones and near-pervasive Internet connectivity only accelerates consumer demand for new applications. And businesses recognize that applications are key to engaging their customers, partnering effectively with their supply chain ecosystem, and empowering their employees.

As a result, the demand for developers has never been higher. The current worldwide population of 18 million developers is growing approximately 20% every year (in contrast to the 0.6% annual growth of the overall US labor force). Yet, despite this torrid growth, demand for developers in 2020 will outstrip supply by an estimated 1 million. Thus, we see tremendous opportunities in helping every developer to Continue reading

Docker Desktop for Windows Home is here!

Last year we announced that Docker had released a preview of Docker Desktop with WSL 2 integration. We are now pleased to announce that we have completed the work to enable experimental support for Windows Home WSL 2 integration. This means that Windows Insider users on 19040 or higher can now install and use Docker Desktop!

Feedback on this first version of Docker Desktop for Windows Home is welcomed! To get started, you will need to be on Windows Insider Preview build 19040 or higher and install the Docker Desktop Edge

What’s in Docker Desktop for Windows Home?

Docker Desktop for WSL 2 Windows Home is a full version of Docker Desktop for Linux container development. It comes with the same feature set as our existing Docker Desktop WSL 2 backend. This gives you: 

  • Latest version of Docker on your Windows machine 
  • Install Kubernetes in one click on Windows Home 
  • Integrated UI to view/manage your running containers 
  • Start Docker Desktop in <5 seconds
  • Use Linux Workspaces
  • Dynamic resource/memory allocation 
  • Networking stack, support for http proxy settings, and trusted CA synchronization 

How do I get started developing with Docker Desktop? 

For the best experience of developing Continue reading

How to deploy on remote Docker hosts with docker-compose

The docker-compose tool is pretty popular for running dockerized applications in a local development environment. All we need to do is write a Compose file containing the configuration for the application’s services and have a running Docker engine for deployment. From here, we can get the application running locally in a few seconds with a single  `docker-compose up` command. 

This was the initial scope but…

As developers look to have the same ease-of-deployment in CI pipelines/production environments as in their development environment, we find today docker-compose being used in different ways and beyond its initial scope. In such cases, the challenge is that docker-compose provided support for running on remote docker engines through the use of the DOCKER_HOST environment variable and -H, –host command line option. This is not very user friendly and managing deployments of Compose applications across multiple environments becomes a burden.

To address this issue, we rely on Docker Contexts to securely deploy Compose applications across different environments and manage them effortlessly from our localhost. The goal of this post is to show how to use contexts to target different environments for deployment and easily switch between them.

We’ll start defining a sample application to use Continue reading

Getting Started with Istio Using Docker Desktop

This is a guest post from Docker Captain Elton Stoneman, a Docker alumni who is now a freelance consultant and trainer, helping organizations at all stages of their container journey. Elton is the author of the book Learn Docker in a Month of Lunches, and numerous Pluralsight video training courses – including Managing Apps on Kubernetes with Istio and Monitoring Containerized Application Health with Docker.

Istio is a service mesh – a software component that runs in containers alongside your application containers and takes control of the network traffic between components. It’s a powerful architecture that lets you manage the communication between components independently of the components themselves. That’s useful because it simplifies the code and configuration in your app, removing all network-level infrastructure concerns like routing, load-balancing, authorization and monitoring – which all become centrally managed in Istio.

There’s a lot of good material for digging into Istio. My fellow Docker Captain Lee Calcote is the co-author of Istio: Up and Running, and I’ve just published my own Pluralsight course Managing Apps on Kubernetes with Istio. But it can be a difficult technology to get started with because you really need a solid background in Kubernetes Continue reading

Docker Donates the cnab-to-oci Library to

Docker is proud and happy to announce the donation of our cnab-to-oci library to the CNAB project 🎉. This project was created last year after Microsoft and Docker moved the CNAB specification to the Linux Foundation’s Joint Development Foundation. At that time, the CNAB specification repository was moved from the deislab GitHub organization to the new cnabio organization. The reference implementations – cnab-go which is the Golang library implementation of the specification and duffle which is the CLI reference implementation – were also moved.

What is cnab-to-oci for?

Docker helped with the development of the CNAB specification and its reference implementations, and led the work on the cnab-to-oci library for sharing a CNAB bundle using an existing container registry. This library is now used by 3 CNAB tools, Docker App, Porter and duffle, as well as Docker Hub. It successfully demonstrated how to push, pull and share a CNAB bundle using a registry. This work will be used as a foundation for the future CNAB Registries specification.

The transfer is already in effect, so starting now please refer to in your Golang imports.

How does cnab-to-oci store a CNAB bundle into a registry?

As you may know, Continue reading

Hack Week: How Docker Drives Innovation from the Inside

Since its founding, Docker’s mission has been to help developers bring their ideas to life by conquering the complexity of app development. With millions of Docker developers worldwide, Docker is the de facto standard for building and sharing containerized apps. 

So what is one source of ideas we use to simplify the lives of developers? It starts with being a company of software developers who builds products for software developers. One of the more creative ways Docker has been driving innovation internally is through hackathons. These hackathons have proven to be a great platform for Docker employees to showcase their talent and provide unique opportunities for teams across Docker’s business functions to come together. Our employees get to have fun while creating solutions to problems that simplify the lives of Docker developers.

At Docker, our engineers are always looking for ways to improve their own workflows so as to ship quality code faster. Hack Week gives us a chance to explore the boundaries of what’s possible, and the winning ‘hacks’ make their way into our products to benefit our global developer community.

-Scott Johnston, Docker CEO

With that context, let’s break down how Docker runs employee hackathons. Docker is Continue reading

Our Favourite Picks from the KubeCon Europe 2020 Schedule

Last Wednesday, the CNCF released the KubeCon Europe 2020 schedule. There are so many talks at KubeCon it can be daunting even to decide what to go to see! Here are some talks by the team at Docker, and some others we think will be particularly interesting. Looking forward to seeing you in Amsterdam!

Simplify Your Cloud-Native Application Packaging and Deployments – Chris Crone

Chris is an engineer in our Paris office and is also co-executive director of the CNAB project. CNAB (Cloud Native Application Bundle) is a specification for bundling up cloud-native applications, which can consist of multiple containers, into a single object that can be pushed to a registry. Open source projects using CNAB, like Docker App or Porter allow you to package apps that would normally require multiple tools like Terraform, Helm, and shell to deploy, into a single tooling agnostic packaging format. These packages can then be shared using existing container registries and used with other CNAB compliant tools. This can really simplify cloud-native development.

Sharing is Caring! Push your Cloud Application to an OCI Registry – Silvin Lubecki & Djordje Lukic

Did you know that you can store anything into a container registry? Continue reading

Changes to APT and YUM repositories

While many people know about Docker, not that many know its history and where it came from. Docker was started as a project in the dotCloud company, founded by Solomon Hykes, which provided a PaaS solution. The project became so successful that dotCloud renamed itself to Docker, Inc. and focused on Docker as its primary product.

As the “Docker project” grew from being a proof of concept shown off at various meetups and at PyCon in 2013 to a real community project, it needed a website where people could learn about it and download it. This is why the “” and “” domains were registered.

With the move from dotCloud to Docker, Inc. and the shift of focus onto the Docker product, it made sense to move everything to the “” domain. This is where you now find the company website, documentation, and of course the APT and YUM repositories at have been there since 2017.

On the 31st of March 2020, we will be shutting down the legacy APT and YUM repositories hosted at and These repositories haven’t been updated with the latest releases of Docker and Continue reading

Introducing the Docker Index: Insight from the World’s Most Popular Container Registry

8 billion pulls! Yes, that’s billion with a B! This number represents a little known level of activity and innovation happening across the community and ecosystem, all in just one average month. How do we know? From the number of pulls and most popular images to top architectures, data from Docker Hub and Docker Desktop provide a window into application development trends in the age of containers. 

Today, we are sharing these findings in something we call the Docker Index – a look at developers’ preferences and trends, as told by using anonymized data from five million Docker Hub and two million Docker Desktop users, as well as countless other developers engaging with content on Hub. 

At Docker, we’re always looking for ways to make life easier for developers. Understanding the what, why and how behind these projects is imperative. As these trends evolve, we will continue to share updates on the findings.

Whether containers will become mainstream is no longer a topic of debate. As the Docker Index data suggests, containers have become a mainstay to how modern, distributed apps are built and shared so they can run anywhere. 

Usage is showing no signs of slowing Continue reading

How We Solved a Report on docker-compose Performance on macOS Catalina

Photo by Caspar Camille Rubin on Unsplash

As a Docker Compose maintainer, my daily duty is to check for newly reported issues and try to help users through misunderstanding and possible underlying bugs. Sometimes issues are very well documented, sometimes they are nothing much but some “please help” message. And sometimes they look really weird and can result in funny investigations. Here is the story of how we solved one such report…

A one-line bug report

An issue was reported as “docker-compose super slow on macOS Catalina” – no version, no details. How should I prioritize this? I don’t even know if the reporter is using the latest version of the tool – the opened issue doesn’t follow the bug reporting template. This is just a one-liner. But for some reason, I decided to take a look at it anyway and diagnose the issue.

Without any obvious explanation for super-slowness, I decided to take a risk and upgrade my own MacBook to OSX Catalina. I was able to reproduce significant slow down in docker-compose execution, waiting seconds for the very first line printed on the console even to display usage on invalid command.

Investigating the issue

In the meantime, some Continue reading

January Virtual Meetup Recap: Improve Image Builds Using the Features in BuildKit

This is a guest post by Docker Captain Nicholas Dille, a blogger, speaker and author with 15 years of experience in virtualization and automation. He works as a DevOps Engineer at Haufe Group, a digital media company located in Freiburg, Germany. He is also a Microsoft Most Valuable Professional.

In this virtual meetup, I share how to improve image builds using the features in BuildKit. BuildKit is an alternative builder with great features like caching, concurrency and the ability to separate your image build into multiple stages – which is useful for separating the build environment from the runtime environment. 

The default builder in Docker is the legacy builder. This is recommended for use when you need support for Windows. However, in nearly every other case, using BuildKit is recommended because of the fast build time, ability to use custom BuildKit front-ends, building stages in parallel and other features.

Catch the full replay below and view the slides to learn:

  • Build cache in BuildKit – instead of relying on a locally present image, buildkit will pull the appropriate layers of the previous image from a registry.
  • How BuildKit helps prevent disclosure of credentials by allowing files to Continue reading

Community Collaboration on Notary v2

One of the most productive meetings I had KubeCon in San Diego last November was a meeting with Docker, Amazon and Microsoft to plan a collaboration around a new version of the CNCF project Notary. We held the Notary v2 kickoff meeting a few weeks later in Seattle in the Amazon offices.

Emphasising that this is a cross-industry collaboration, we had eighteen people in the room (with more dialed in) from Amazon, Microsoft, Docker, IBM, Google, Red Hat, Sylabs and JFrog. This represented all the container registry providers and developers, other than the VMware Harbor developers who could unfortunately not make it in person. Unfortunately, we forgot to take a picture of everyone!

The consensus and community are important because of the aims of Notary v2. But let’s go back a bit as some of you may not know what Notary is and what it is for.

The Notary project was originally started at Docker back in 2015 to provide a general signing Continue reading

Faster builds in Docker Compose 1.25.1 thanks to BuildKit Support

One of the most requested features for the docker-compose tool is definitely support for building using Buildkit which is an alternative builder with great capabilities, like caching, concurrency and ability to use custom BuildKit front-ends just to mention a few… Ahhh with a nice blue output! And the good news is that Docker Compose 1.25.1 – that was just released early January – includes BuildKit support!

BuildKit support for Docker Compose is actually achieved by redirecting the docker-compose build to the Docker CLI with a limited feature set.

Enabling Buildkit build

To enable this, we have to align some stars.

First, it requires that the Docker CLI binary present in your PATH:

$ which

Second, docker-compose has to be run with the environment variable COMPOSE_DOCKER_CLI_BUILD set to 1 like in:

$ COMPOSE_DOCKER_CLI_BUILD=1 docker-compose build

This instruction tells docker-compose to use the Docker CLI when executing a build. You should see the same build output, but starting with the experimental warning.

As docker-compose passes its environment variables to the Docker CLI, we can also tell the CLI to use BuildKit instead of the default builder. To accomplish that, we can execute this:


A Continue reading

Docker Desktop release 2.2 is here!

We are excited to announce that we released a new Docker Desktop version today! Thanks to the user feedback on the new features initially released in the Edge channel, we are now ready to publish them into Stable. 

Before getting to each feature into detail, let’s see what’s new in Docker Desktop 2.2:

  • WSL 2 as a technical preview, allowing access to the full system resources, improved boot time, access to Linux workspaces and improved file system performance
  • A new file sharing implementation for Windows, improving the developer inner loop user experience
  • A New Integrated Desktop Dashboard, to see at once glance your local running containers and Compose applications, and easily manage them.

WSL 2 – New architecture 

Back in July we released on Edge the technical preview of Docker Desktop for WSL 2, where we included an experimental integration of Docker running on an existing user Linux distribution. We learnt from our experience and re-architected our solution (covered in Simon’s blog)

This new architecture for WSL 2 allows users to: 

  • Use Kubernetes on the WSL 2 backend
  • Work with just WSL 2/turn off the traditional HyperV VM while working with WSL 2
  • Continue Continue reading
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