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Deployments that are based on Windows Containers are applicable to Cloud-Optimized applications and Cloud-Native applications.
- Windows Containers share a kernel with the container host and all the containers running on the host. In contrast, with Hyper-V Containers the kernel of the container host is not shared with the Hyper-V Containers. What this means is that Windows Containers are isolated from each other but they run directly on Windows Server 2016.
- For my programming work, I tend to assume that I have a Linux environnement. That is true whether I am under Windows, under macOS or under a genuine Linux. How do I emulate Linux wherever I go? I use docker containers. Effectively, the docker container gives me a small subsystem where everything is “as if” Continue reading Computational overhead due to Docker under macOS.
However, in this guide and especially in the following sections, it mostly focuses on using Windows Containers for Cloud-Optimized applications where you don't need to rearchitect your application.
What are containers? (Linux or Windows)
Containers are a way to wrap up an application into its own isolated package. In its container, the application is not affected by applications or processes that exist outside of the container. Everything the application depends on to run successfully as a process is inside the container. Wherever the container might move, the requirements of the application will always be met, in terms of direct dependencies, because it is bundled with everything that it needs to run (library dependencies, runtimes, and so on).
The main characteristic of a container is that it makes the environment the same across different deployments because the container itself comes with all the dependencies it needs. You can debug the application on your machine, and then deploy it to another machine, with the same environment guaranteed.
A container is an instance of a container image. A container image is a way to package an app or service (like a snapshot), and then deploy it in a reliable and reproducible way. You could say that Docker is not only a technology-it's also a philosophy and a process.
As containers daily become more common, they are becoming an industry-wide 'unit of deployment.'
Jun 09, 2020 Canonical this week announced it’s now possible to deploy its lightweight distribution of Kubernetes on both Windows and MacOS platforms. Alex Chalikas, a product manager for Canonical, says that while the MicroK8s platform was originally intended to be employed as an instance of Kubernetes that developers could easily deploy on their desktops, it has since also morphed into an.
Benefits of containers (Docker Engine on Linux or Windows)
Building applications by using containers-which also might be defined as lightweight building blocks-offers a significant increase in agility for building, shipping, and running any application, across any infrastructure.
With containers, you can take any app from development to production with little or no code change, thanks to Docker integration across Microsoft developer tools, operating systems, and cloud.
When you deploy to plain VMs, you probably already have a method in place for deploying ASP.NET apps to your VMs. It's likely, though, that your method involves multiple manual steps or complex automated processes by using a deployment tool like Puppet, or a similar tool. You might need to perform tasks like modifying configuration items, copying application content between servers, and running interactive setup programs based on .msi setups, followed by testing. All those steps in the deployment add time and risk to deployments. You will get failures whenever a dependency is not present in the target environment.
In Windows Containers, the process of packaging applications is fully automated. Windows Containers is based on the Docker platform, which offers automatic updates and rollbacks for container deployments. The main improvement you get from using the Docker engine is that you create images, which are like snapshots of your application, with all its dependencies. The images are Docker images (a Windows container image, in this case). The images run ASP.NET apps in containers, without going back to source code. The container snapshot becomes the unit of deployment.
Many organizations are containerizing existing monolithic applications for the following reasons:
- Release agility through improved deployment. Containers offer a consistent deployment contract between development and operations. When you use containers, you won't hear developers say, 'It works on my machine, why not in production?' They can say, 'It runs as a container, so it will run in production.' The packaged application, with all its dependencies, can be executed in any supported container-based environment. It will run the way it was intended to run in all deployment targets (dev, QA, staging, production). Containers eliminate most frictions when they move from one stage to the next, which greatly improves deployment, and you can ship faster.
- Cost reductions. Containers lead to lower costs, either by the consolidation and removal of existing hardware, or from running applications at a higher density per unit of hardware.
- Portability. Containers are modular and portable. Docker containers are supported on any server operating system (Linux and Windows), in any major public cloud (Microsoft Azure, Amazon AWS, Google, IBM), and in on-premises and private or hybrid cloud environments.
- Control. Containers offer a flexible and secure environment that's controlled at the container level. A container can be secured, isolated, and even limited by setting execution constraint policies on the container. As detailed in the section about Windows Containers, Windows Server 2016 and Hyper-V containers offer additional enterprise support options.
Significant improvements in agility, portability, and control ultimately lead to significant cost reductions when you use containers to develop and maintain applications.
What is Docker?
Docker is an open-source project that automates the deployment of applications as portable, self-sufficient containers that can run in the cloud or on-premises. Docker is also a company that promotes and evolves this technology. The company works in collaboration with cloud, Linux, and Windows vendors, including Microsoft.
Figure 4-6. Docker deploys containers at all layers of the hybrid cloud
To someone familiar with virtual machines, containers might appear to be remarkably similar. A container runs an operating system, has a file system, and can be accessed over a network, just like a physical or virtual computer system. However, the technology and concepts behind containers are vastly different from virtual machines. From a developer point of view, a container must be treated more like a single process. In fact, a container has a single entry point for one process.
Docker containers (for simplicity, containers) can run natively on Linux and Windows. When running regular containers, Windows containers can run only on Windows hosts (a host server or a VM), and Linux containers can run only on Linux hosts. However, in recent versions of Windows Server and Hyper-V containers, a Linux container can also run natively on Windows Server by using the Hyper-V isolation technology that currently is available only in Windows Server Containers.
In the near future, mixed environments that have both Linux and Windows containers will be possible and even common.
Benefits of Windows Containers for your existing .NET applications
The benefits of using Windows Containers are fundamentally the same benefits you get from containers in general. Using Windows Containers is about greatly improving agility, portability, and control.
Existing .NET applications refer to those applications that were created using the .NET Framework. For example, they might be traditional ASP.NET web applications-they don't use .NET Core, which is newer and runs cross-platform on Linux, Windows, and MacOS.
The main dependency in the .NET Framework is Windows. It also has secondary dependencies, like IIS, and System.Web in traditional ASP.NET.
A .NET Framework application must run on Windows, period. If you want to containerize existing .NET Framework applications and you can't or don't want to invest in a migration to .NET Core ('If it works properly, don't migrate it'), the only choice you have for containers is to use Windows Containers.
So, one of the main benefits of Windows Containers is that they offer you a way to modernize your existing .NET Framework applications that are running on Windows-through containerization. Ultimately, Windows Containers gets you the benefits that you are looking for by using containers-agility, portability, and better control.
Choose an OS to target with .NET-based containers
Given the diversity of operating systems that are supported by Docker, as well as the differences between .NET Framework and .NET Core, you should target a specific OS and specific versions based on the framework you are using.
For Windows, you can use Windows Server Core or Windows Nano Server. These Windows versions provide different characteristics (like IIS versus a self-hosted web server like Kestrel) that might be needed by .NET Framework or .NET Core applications.
For Linux, multiple distros are available and supported in official .NET Docker images (like Debian).
Figure 4-7 shows OS versions that you can target, depending on the app's version of the .NET Framework.
Figure 4-7. Operating systems to target based on .NET Framework version
In migration scenarios for existing or legacy applications that are based on .NET Framework applications, the main dependencies are on Windows and IIS. Your only option is to use Docker images based on Windows Server Core and the .NET Framework.
When you add the image name to your Dockerfile file, you can select the operating system and version by using a tag, as in the following examples for .NET Framework-based Windows container images:
Tag | System and version |
---|---|
microsoft/dotnet-framework:4.x-windowsservercore | .NET Framework 4.x on Windows Server Core |
microsoft/aspnet:4.x-windowsservercore | .NET Framework 4.x with additional ASP.NET customization, on Windows Server Core |
For .NET Core (cross-platform for Linux and Windows), the tags would look like the following:
Tag | System and version |
---|---|
microsoft/dotnet:2.0.0-runtime | .NET Core 2.0 runtime-only on Linux |
microsoft/dotnet:2.0.0-runtime-nanoserver | .NET Core 2.0 runtime-only on Windows Nano Server |
Multi-arch images
Beginning in mid-2017, you can also use a new feature in Docker called multi-arch images. .NET Core Docker images can use multi-arch tags. Your Dockerfile files no longer need to define the operating system that you are targeting. The multi-arch feature allows a single tag to be used across multiple machine configurations. For instance, with multi-arch, you can use one common tag: microsoft/dotnet:2.0.0-runtime. If you pull that tag from a Linux container environment, you get the Debian-based image. If you pull that tag from a Windows container environment, you get the Nano Server-based image.
For .NET Framework images, because the traditional .NET Framework supports only Windows, you cannot use the multi-arch feature.
Windows container types
Like Linux containers, Windows Server containers are managed by using Docker Engine. Unlike Linux containers, Windows containers include two different container types, or run times-Windows Server containers and Hyper-V isolation.
Windows Server containers: Provides application isolation through process and namespace isolation technology. A Windows Server container shares a kernel with the container host and all containers that are running on the host. These containers do not provide a hostile security boundary and should not be used to isolate untrusted code. Because of the shared kernel space, these containers require the same kernel version and configuration.
Hyper-V isolation: Expands on the isolation provided by Windows Server Containers by running each container on a highly optimized VM. In this configuration, the kernel of the container host is not shared with other containers on the same host. These containers are designed for hostile multitenant hosting, with the same security assurances of a VM. Because these containers don't share the kernel with the host or other containers on the host, they can run kernels with different versions and configurations (with supported versions). For example, all Windows containers on Windows 10 use Hyper-V isolation to utilize the Windows Server kernel version and configuration.
Running a container on Windows with or without Hyper-V isolation is a run-time decision. You might choose to create the container with Hyper-V isolation initially, and at run time, choose to run it as a Windows Server container instead.
Additional resources
- Windows Containers documentation
- Windows Containers fundamentals
- Infographic: Microsoft and containers
The container ecosystem in Azure
In previous sections, it's been explained what the benefits of Docker containers are as well as details on the specific container images for .NET applications. All that generic information is fundamental in order to develop or containerize an application.However, when thinking about the production deployment environment or even QA and Dev/Test environments, Microsoft Azure provides an open and broad variety of choices, a full container ecosystem in the cloud (shown in the diagram below). Depending on your specific application's needs, you should choose one or another Azure product.
Figure 4-7.5. The container ecosystem in Azure
From the container ecosystem in Azure, the following products supporting containers that are considered infrastructure:
- Azure Container Instances (ACI)
- Azure Virtual Machines (With container's support)
- Azure Virtual Machine Scale Sets (With container's support)
From those three, ACI provides a great benefit, which is the fact that you don't need to maintain the underlying OS, no need for you to upgrade/patch, etc. but ACI still is positioned in the infrastructure level, as better explained in the upcoming sections of this book.
The products in Azure supporting containers that are at the same time positioned more in the PaaS (Platform as a Service) level are:
- Azure App Service
- Azure Kubernetes Service (AKS and ACS)
- Azure Batch
Then, Azure Container Registry is a high scalable container registry hosted in Azure that you can use from all the previous products when registering and deploying your custom container images.
In addition, from your containers, you can consume other managed services in Azure like Azure SQL Database, Azure Redis cache, Azure Cosmos DB, etc. plus there are third-party solutions/platforms available in Azure Marketplace like Cloud Foundry and OpenShift where you can also use containers within Azure.
In the next sections, you can explore Microsoft's recommendations on when to use each of those Azure products and solutions specifically when targeting Windows Containers.
Estimated reading time: 17 minutes Welcome to Docker Desktop!
The Docker Desktop for Mac section contains information about the Docker Desktop Community Stable release. For information about features available in Edge releases, see the Edge release notes. For information about Docker Desktop Enterprise (DDE) releases, see Docker Desktop Enterprise.
Docker is a full development platform to build, run, and share containerized applications. Docker Desktop is the best way to get started with Docker on Mac.
See Install Docker Desktop for download information, system requirements, and installation instructions.
Check versions
Ensure your versions of
docker
and docker-compose
areup-to-date and compatible with Docker.app
. Your output may differ if you arerunning different versions.Explore the application
- Open a command-line terminal and test that your installation works byrunning the simple Docker image,hello-world:
- Start a Dockerized web server. Like the
hello-world
image above, if theimage is not found locally, Docker pulls it from Docker Hub. - In a web browser, go to
http://localhost/
to view the nginx homepage.Because we specified the default HTTP port, it isn’t necessary to append:80
at the end of the URL.Early beta releases useddocker
as the hostname to build the URL. Now,ports are exposed on the private IP addresses of the VM and forwarded tolocalhost
with no other host name set. - View the details on the container while your web server is running (with
docker container ls
ordocker ps
): - Stop and remove containers and images with the following commands. Use the“all” flag (
--all
or-a
) to view stopped containers.
Preferences
Choose the Docker menu > Preferences from themenu bar and configure the runtime options described below.
General
On the General tab, you can configure when to start and update Docker:
- Start Docker Desktop when you log in: Automatically starts Docker Desktop when you open your session.
- Automatically check for updates: By default, Docker Desktop automatically checks for updates and notifies you when an update is available. You can manually check for updates anytime by choosing Check for Updates from the main Docker menu.
- Include VM in Time Machine backups: Select this option to back up the Docker Desktop virtual machine. This option is disabled by default.
- Securely store Docker logins in macOS keychain: Docker Desktop stores your Docker login credentials in macOS keychain by default.
- Send usage statistics: Docker Desktop sends diagnostics, crash reports, and usage data. This information helps Docker improve and troubleshoot the application. Clear the check box to opt out.Click Switch to the Edge version to learn more about Docker Desktop Edge releases.
Resources
The Resources tab allows you to configure CPU, memory, disk, proxies, network, and other resources.
Advanced
On the Advanced tab, you can limit resources available to Docker.
Advanced settings are:
CPUs: By default, Docker Desktop is set to use half the number of processorsavailable on the host machine. To increase processing power, set this to ahigher number; to decrease, lower the number.
Memory: By default, Docker Desktop is set to use
2
GB runtime memory,allocated from the total available memory on your Mac. To increase the RAM, set this to a higher number. To decrease it, lower the number.Swap: Configure swap file size as needed. The default is 1 GB.
Disk image size: Specify the size of the disk image.
Disk image location: Specify the location of the Linux volume where containers and images are stored.
You can also move the disk image to a different location. If you attempt to move a disk image to a location that already has one, you get a prompt asking if you want to use the existing image or replace it.
File sharing
Use File sharing to allow local directories on the Mac to be shared with Linux containers.This is especially useful forediting source code in an IDE on the host while running and testing the code in a container.By default the
/Users
, /Volume
, /private
, /tmp
and /var/folders
directory are shared. If your project is outside this directory then it must be addedto the list. Otherwise you may get Mounts denied
or cannot start service
errors at runtime.File share settings are:
- Add a Directory: Click
+
and navigate to the directory you want to add. - Apply & Restart makes the directory available to containers using Docker’sbind mount (
-v
) feature.There are some limitations on the directories that can be shared:- The directory must not exist inside of Docker.
For more information, see:
- Namespaces in the topic onosxfs file system sharing.
- Volume mounting requires file sharing for any project directories outside of
/Users
.)
Proxies
Docker Desktop detects HTTP/HTTPS Proxy Settings from macOS and automaticallypropagates these to Docker. For example, if you set yourproxy settings to
http://proxy.example.com
, Docker uses this proxy whenpulling containers.Your proxy settings, however, will not be propagated into the containers you start.If you wish to set the proxy settings for your containers, you need to defineenvironment variables for them, just like you would do on Linux, for example:
For more information on setting environment variables for running containers,see Set environment variables.
Network
You can configure Docker Desktop networking to work on a virtual private network (VPN). Specify a network address translation (NAT) prefix and subnet mask to enable Internet connectivity.
Docker Engine
The Docker Engine page allows you to configure the Docker daemon to determine how your containers run.
Type a JSON configuration file in the box to configure the daemon settings. For a full list of options, see the Docker Enginedockerd commandline reference.
Click Apply & Restart to save your settings and restart Docker Desktop.
Command Line
On the Command Line page, you can specify whether or not to enable experimental features.
Experimental features provide early access to future product functionality.These features are intended for testing and feedback only as they may changebetween releases without warning or can be removed entirely from a futurerelease. Experimental features must not be used in production environments.Docker does not offer support for experimental features.
To enable experimental features in the Docker CLI, edit the
config.json
file and set experimental
to enabled.To enable experimental features from the Docker Desktop menu, clickSettings (Preferences on macOS) > Command Line and then turn onthe Enable experimental features toggle. Click Apply & Restart.
For a list of current experimental features in the Docker CLI, see Docker CLI Experimental features.
On both Docker Desktop Edge and Stable releases, you can toggle the experimental features on and off. If you toggle the experimental features off, Docker Desktop uses the current generally available release of Docker Engine.
You can see whether you are running experimental mode at the command line. If
Experimental
is true
, then Docker is running in experimental mode, as shownhere. (If false
, Experimental mode is off.)Kubernetes
Docker Desktop includes a standalone Kubernetes server that runs on your Mac, sothat you can test deploying your Docker workloads on Kubernetes.
The Kubernetes client command,
kubectl
, is included and configured to connectto the local Kubernetes server. If you have kubectl
already installed andpointing to some other environment, such as minikube
or a GKE cluster, be sureto change context so that kubectl
is pointing to docker-desktop
:If you installed
kubectl
with Homebrew, or by some other method, andexperience conflicts, remove /usr/local/bin/kubectl
.- To enable Kubernetes support and install a standalone instance of Kubernetesrunning as a Docker container, select Enable Kubernetes. To set Kubernetes as thedefault orchestrator, select Deploy Docker Stacks to Kubernetes by default.Click Apply & Restart to save the settings. This instantiates images required to run the Kubernetes server as containers, and installs the
/usr/local/bin/kubectl
command on your Mac.When Kubernetes is enabled and running, an additional status bar item displaysat the bottom right of the Docker Desktop Settings dialog.The status of Kubernetes shows in the Docker menu and the context points todocker-desktop
. - By default, Kubernetes containers are hidden from commands like
dockerservice ls
, because managing them manually is not supported. To make themvisible, select Show system containers (advanced) and click Apply andRestart. Most users do not need this option. - To disable Kubernetes support at any time, clear the Enable Kubernetes check box. TheKubernetes containers are stopped and removed, and the
/usr/local/bin/kubectl
command is removed.For more about using the Kubernetes integration with Docker Desktop, seeDeploy on Kubernetes.
Reset
Reset and Restart options
On Docker Desktop Mac, the Restart Docker Desktop, Reset to factory defaults, and other reset options are available from the Troubleshoot menu.
For information about the reset options, see Logs and Troubleshooting.
Dashboard
The Docker Desktop Dashboard enables you to interact with containers and applications and manage the lifecycle of your applications directly from your machine. The Dashboard UI shows all running, stopped, and started containers with their state. It provides an intuitive interface to perform common actions to inspect and manage containers and existing Docker Compose applications. For more information, see Docker Desktop Dashboard.
Add TLS certificates
You can add trusted Certificate Authorities (CAs) (used to verify registryserver certificates) and client certificates (used to authenticate toregistries) to your Docker daemon.
Add custom CA certificates (server side)
All trusted CAs (root or intermediate) are supported. Docker Desktop creates acertificate bundle of all user-trusted CAs based on the Mac Keychain, andappends it to Moby trusted certificates. So if an enterprise SSL certificate istrusted by the user on the host, it is trusted by Docker Desktop.
To manually add a custom, self-signed certificate, start by adding thecertificate to the macOS keychain, which is picked up by Docker Desktop. Here isan example:
Or, if you prefer to add the certificate to your own local keychain only (ratherthan for all users), run this command instead:
See also, Directory structures forcertificates.
Note: You need to restart Docker Desktop after making any changes to thekeychain or to the
~/.docker/certs.d
directory in order for the changes totake effect.For a complete explanation of how to do this, see the blog post AddingSelf-signed Registry Certs to Docker & Docker Desktop forMac.
Add client certificates
You can put your client certificates in
~/.docker/certs.d/<MyRegistry>:<Port>/client.cert
and~/.docker/certs.d/<MyRegistry>:<Port>/client.key
.When the Docker Desktop application starts, it copies the
~/.docker/certs.d
folder on your Mac to the /etc/docker/certs.d
directory on Moby (the DockerDesktop xhyve
virtual machine).- You need to restart Docker Desktop after making any changes to the keychainor to the
~/.docker/certs.d
directory in order for the changes to takeeffect. - The registry cannot be listed as an insecure registry (see DockerEngine. Docker Desktop ignores certificates listedunder insecure registries, and does not send client certificates. Commandslike
docker run
that attempt to pull from the registry produce errormessages on the command line, as well as on the registry.
Directory structures for certificates
If you have this directory structure, you do not need to manually add the CAcertificate to your Mac OS system login:
The following further illustrates and explains a configuration with customcertificates:
You can also have this directory structure, as long as the CA certificate isalso in your keychain.
To learn more about how to install a CA root certificate for the registry andhow to set the client TLS certificate for verification, seeVerify repository client with certificatesin the Docker Engine topics.
Install shell completion
Docker Desktop comes with scripts to enable completion for the
docker
and docker-compose
commands. The completion scripts may befound inside Docker.app
, in the Contents/Resources/etc/
directory and can beinstalled both in Bash and Zsh.Bash
Bash has built-in support forcompletion To activate completion for Docker commands, these files need to becopied or symlinked to your
bash_completion.d/
directory. For example, if youinstalled bash via Homebrew:Add the following to your
~/.bash_profile
:Windows Container For Macos Pc
OR
Zsh
In Zsh, the completionsystem takes care of things. To activate completion for Docker commands,these files need to be copied or symlinked to your Zsh
site-functions/
directory. For example, if you installed Zsh via Homebrew:Fish-Shell
Fish-shell also supports tab completion completionsystem. To activate completion for Docker commands,these files need to be copied or symlinked to your Fish-shell
completions/
directory.Create the
completions
directory:Now add fish completions from docker.
Give feedback and get help
To get help from the community, review current user topics, join or start adiscussion, log on to our Docker Desktop for Macforum.
To report bugs or problems, log on to Docker Desktop for Mac issues onGitHub,where you can review community reported issues, and file new ones. SeeLogs and Troubleshooting for more details.
For information about providing feedback on the documentation or update it yourself, see Contribute to documentation.
Docker Hub
Select Sign in /Create Docker ID from the Docker Desktop menu to access your Docker Hub account. Once logged in, you can access your Docker Hub repositories and organizations directly from the Docker Desktop menu.
For more information, refer to the following Docker Hub topics:
Two-factor authentication
Docker Desktop enables you to sign into Docker Hub using two-factor authentication. Two-factor authentication provides an extra layer of security when accessing your Docker Hub account.
You must enable two-factor authentication in Docker Hub before signing into your Docker Hub account through Docker Desktop. For instructions, see Enable two-factor authentication for Docker Hub.
After you have enabled two-factor authentication:
- Go to the Docker Desktop menu and then select Sign in / Create Docker ID.
- Enter your Docker ID and password and click Sign in.
- After you have successfully signed in, Docker Desktop prompts you to enter the authentication code. Enter the six-digit code from your phone and then click Verify.
After you have successfully authenticated, you can access your organizations and repositories directly from the Docker Desktop menu.
Where to go next
- Try out the walkthrough at Get Started.
- Dig in deeper with Docker Labs examplewalkthroughs and source code.
- For a summary of Docker command line interface (CLI) commands, seeDocker CLI Reference Guide.
- Check out the blog post, What’s New in Docker 17.06 Community Edition(CE).