Some time ago I compared disk drivers performance in KVM. Today I compared different storage formats - raw and qcow2. Let's have a look: Test procedure: Create an empty 10 GB image, attach to VM using VirtIO driver, boot F20 Alpha Live x8664, measure the time of installation. Ensure any volume directories on the host are owned by the same user you specify and any permissions issues will vanish like magic. In this instance PUID=1000 and PGID=1000, to find yours use id user as below: $ id username uid=1000 (dockeruser) gid=1000 (dockergroup) groups=1000 (dockergroup).

• Docker Qcow2 Vs Rawlings
• Docker Qcow2 Vs Raw Download
• Docker Qcow2 Vs Raw Data
• Docker Qcow2 Vs Raw Dog Food
• Docker Mac Raw Vs Qcow2

• Cloud Base image for Openstack. 319MB qcow2 image. Download Verify. Fedora 34 Cloud Base images. Fedora Cloud Base images are for creating general purpose virtual machines (VMs). You can use the Qcow 2 image for use with Openstack or the compressed raw image. If you are not sure what to use, try the raw image.
• Docker Desktop can run inside a Windows 10 VM running on apps like Parallels or VMware Fusion on a Mac provided that the VM is properly configured. However, problems and intermittent failures may still occur due to the way these apps virtualize the hardware. For these reasons, Docker Desktop is not supported in nested virtualization scenarios.

Estimated reading time: 10 minutes

General

What are the system requirements for Docker Desktop?

For information about Docker Desktop system requirements, see Docker Desktop for Mac system requirements and Docker Desktop for Windows system requirements.

What is an experimental feature?

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.

For a list of current experimental features in the Docker CLI, see Docker CLI Experimental features.

Where can I find information about diagnosing and troubleshooting Docker Desktop issues?

You can find information about diagnosing and troubleshooting common issues in the Troubleshooting topic. See Mac Logs and Troubleshooting topic and Windows Logs and Windows Logs and Troubleshooting.

If you do not find a solution in Troubleshooting, browse issues ondocker/for-mac or docker/for-win GitHub repository, or create a new one.

How do I connect to the remote Docker Engine API?

To connect to the remote Engine API, you might need to provide the location of the Engine API for Docker clients and development tools.

Mac and Windows WSL 2 users can connect to the Docker Engine through a Unix socket: unix:///var/run/docker.sock.

If you are working with applications like Apache Maventhat expect settings for DOCKER_HOST and DOCKER_CERT_PATH environmentvariables, specify these to connect to Docker instances through Unix sockets.

For example:

Docker Desktop Windows users can connect to the Docker Engine through a named pipe: npipe:////./pipe/docker_engine, or TCP socket at this URL:tcp://localhost:2375.

For details, see Docker Engine API.

How do I connect from a container to a service on the host?

Both Mac and Windows have a changing IP address (or none if you have no network access). On both Mac and Windows, we recommend that you connect to the special DNS name host.docker.internal, which resolves to the internal IP address used by the host. This is for development purposes and does not work in a production environment outside of Docker Desktop.

For more information and examples, see how to connect from a container to a service on the hoston Mac and on Windows.

How do I connect to a container from Mac or Windows?

We recommend that you publish a port, or connect from another container. Port forwarding works for localhost; --publish, -p, or -P all work.

For more information and examples, seeI want to connect to a container from Mac and I want to connect to a container from Windows.

How do I add custom CA certificates?

Docker Desktop supports all trusted certificate authorities (CAs) (root or intermediate). For more information on adding server and client side certs, seeAdd TLS certificates on Mac and Add TLS certificates on Windows.

Can I pass through a USB device to a container?

Unfortunately, it is not possible to pass through a USB device (or aserial port) to a container as it requires support at the hypervisor level.

Can I run Docker Desktop in nested virtualization scenarios?

Docker Desktop can run inside a Windows 10 VM running on apps like Parallels orVMware Fusion on a Mac provided that the VM is properly configured. However,problems and intermittent failures may still occur due to the way these appsvirtualize the hardware. For these reasons, Docker Desktop is not supported innested virtualization scenarios. It might work in some cases, and not in others.

For more information, see Running Docker Desktop in nested virtualization scenarios.

Releases

When will Docker Desktop move to a cumulative release stream?

Starting with version 3.0.0, Docker Desktop will be available as a single, cumulative release stream. This is the same version for both Stable and Edge users. The next release after Docker Desktop 3.0.0 will be the first to be applied as a delta update. For more information, see Automatic updates.

How do new users install Docker Desktop?

Each Docker Desktop release is also delivered as a full installer for new users. The same will apply if you have skipped a version, although this doesn’t normally happen as updates will be applied automatically.

How frequent will new releases be?

New releases will be available roughly monthly, similar to Edge today, unless there are critical fixes that need to be released sooner.

How do I ensure that all users on my team are using the same version?

Previously you had to manage this yourself: now it will happen automatically as a side effect of all users being on the latest version.

My colleague has got a new version but I haven’t got it yet.

Sometimes we may roll out a new version gradually over a few days. Therefore, if you wait, it will turn up soon. Alternatively, you can select Check for Updates from the Docker menu to jump the queue and get the latest version immediately.

Where can I find information about Stable and Edge releases?

Starting with Docker Desktop 3.0.0, Stable and Edge releases are combined into a single, cumulative release stream for all users.

Support

Does Docker Desktop offer support?

Yes, Docker Desktop offers support for Pro and Team users. For more information, see Docker Desktop Support.

For information about the pricing plans and to upgrade your existing account, see Docker pricing.

What kind of feedback are you looking for?

Everything is fair game. We’d like your impressions on the download-installprocess, startup, functionality available, the GUI, usefulness of the app,command line integration, and so on. Tell us about the issues you are experiencing, what you like, or request a new feature through our public Docker Roadmap.

How is personal data handled in Docker Desktop?

When uploading diagnostics to help Docker with investigating issues, the uploaded diagnostics bundle may contain personal data such as usernames and IP addresses. The diagnostics bundles are only accessible to Docker, Inc.employees who are directly involved in diagnosing Docker Desktop issues.

By default, Docker, Inc. will delete uploaded diagnostics bundles after 30 days. You may also request the removal of a diagnostics bundle by either specifying the diagnostics ID or via your GitHub ID (if the diagnostics ID is mentioned in a GitHub issue). Docker, Inc. will only use the data in the diagnostics bundle to investigate specific user issues, but may derive high-level (non personal) metrics such as the rate of issues from it.

For more information, see Docker Data Processing Agreement.

Mac FAQs

What is Docker.app?

Docker.app is Docker Desktop on Mac. It bundles the Docker client and Docker Engine. Docker.app uses the macOS Hypervisor.framework to run containers.

Is Docker Desktop compatible with Apple silicon processors?

Yes, you can now install Docker Desktop for Mac on Apple silicon. For more information, see Docker Desktop for Apple silicon.

What is HyperKit?

HyperKit is a hypervisor built on top of the Hypervisor.framework in macOS. It runs entirely in userspace and has no other dependencies.

We use HyperKit to eliminate the need for other VM products, such as OracleVirtualBox or VMWare Fusion.

What is the benefit of HyperKit?

HyperKit is thinner than VirtualBox and VMWare fusion, and the version we include is customized for Docker workloads on Mac.

Why is com.docker.vmnetd still running after I quit the app?

Docker Qcow2 Vs Rawlings

The privileged helper process com.docker.vmnetd is started by launchd andruns in the background. The process does not consume any resources unlessDocker.app connects to it, so it’s safe to ignore.

Windows FAQs

Can I use VirtualBox alongside Docker Desktop?

Yes, you can run VirtualBox along with Docker Desktop if you have enabled the Windows Hypervisor Platform feature on your machine.

Docker Qcow2 Vs Raw Download

Why is Windows 10 required?

Docker Desktop uses the Windows Hyper-V features. While older Windows versions have Hyper-V, their Hyper-V implementations lack features critical for Docker Desktop to work.

Can I install Docker Desktop on Windows 10 Home?

If you are running Windows 10 Home (starting with version 1903), you can install Docker Desktop for Windows with the WSL 2 backend.

Can I run Docker Desktop on Windows Server?

No, running Docker Desktop on Windows Server is not supported.

How do I run Windows containers on Windows Server?

You can install a native Windows binary which allows you to develop and runWindows containers without Docker Desktop. For more information, see the tutorial about running Windows containers on Windows Server inGetting Started with Windows Containers.

Why do I see the Docker Desktop Access Denied error message when I try to start Docker Desktop?

Docker Desktop displays the Docker Desktop - Access Denied error if a Windows user is not part of the docker-users group.

If your admin account is different to your user account, add the docker-users group. Run Computer Management as an administrator and navigate to Local Users* and Groups > Groups > docker-users.

Right-click to add the user to the group. Log out and log back in for the changes to take effect.

Why does Docker Desktop fail to start when anti-virus software is installed?

Some anti-virus software may be incompatible with Hyper-V and Windows 10 builds which impact DockerDesktop. For more information, see Docker Desktop fails to start when anti-virus software is installed.

Can I change permissions on shared volumes for container-specific deployment requirements?

Docker Desktop does not enable you to control (chmod)the Unix-style permissions on shared volumes fordeployed containers, but rather sets permissions to a default value of0777(read, write, execute permissions for user and forgroup) which is not configurable.

For workarounds and to learn more, seePermissions errors on data directories for shared volumes.

How do symlinks work on Windows?

Docker Desktop supports two types of symlinks: Windows native symlinks and symlinks created inside a container.

The Windows native symlinks are visible within the containers as symlinks, whereas symlinks created inside a container are represented as mfsymlinks: target=”blank” rel=”noopener” class=””}. These are regular Windows files with a special metadata. Therefore the symlinks created inside a container appear as symlinks inside the container, but not on the host.

Containerization has become an increasingly relevant topic. There are already thousands, if not tens of thousands, of articles and posts written about popular solutions like LXC and Docker.
In today’s article, we’d like to discuss systemd-nspawn, a systemd component for creating isolated environments. Systemd is already a standard in the world of Linux and in light of this, it wouldn’t be unfounded to suggest that the potential for systemd-nspawn will significantly expand in the near future. For this reason, we think now would be a good time to better acquaint ourselves with this tool.

systemd-nspawn: General Information

The name systemd-nspawn is an abbreviation of namespaces spawn. From this name alone we can see that systemd-nspawn only manages isolated processes; it cannot isolate resources (however, this can be done with systemd, which we’ll talk about later on).

Using systemd-nspawn, we can create a fully isolated environment, which will automatically monitor the /proc and /sys pseudo-file systems and create an isolated loopback interface and separate name space for process identifiers (PID). Inside these spaces, we can launch Linux-based operating systems.

Unlike Docker, systemd-nspawn does not have a special image repository, but images can be created and uploaded using any third-party program. tar, raw, qcow2, and dkr (the Docker image format; this isn’t written anywhere in the systemd-nspawn documentation and its author made quite an effort to avoid using the word Docker) image formats are supported. Images are managed based on the btrfs file system.

Launching Debian in a Container

In this introduction to systemd-nspawn, we’ll start with a simple, yet extremely practical example.
We’ll create an isolated environment for launching Debian on a server running Fedora. All commands given below are for Fedora 22 and version 219 of systemd; commands may be different for different Linux distributions and versions of systemd.

We start by installing the necessary dependencies:

Then we create a file system for the future container:

Once we’ve finished our prep, we can launch the container:

A prompt for the guest operating system will appear in the console:

We set the root password:

Now we leave the container by entering the keyboard combination Ctrl+ ]]] (some keyboards will use % instead of ]), and then run the following command:

Here we have the -b (or –boot) flag, which indicates that when an operating system is launched in the container, init should be run each time a daemon is launched. This flag can only be used if the OS launched within the container supports systemd. If it doesn’t, there’s no guarantee the system will load.

After this, the system will prompt you for the login and password.

And there you have it! A complete operating system has just been launched in an isolated environment. Now we need to configure the network. We leave the container and build a bridge for connecting to the interface on the main host:

We assign the bridge an IP address:

Afterwards, we run the command:

We can also set up a network using the option –network-ipvlan, which connects the container to a given interface on the primary host using ipvlan:

Launching a Container as a Service

With systemd, containers can be configured to automatically launch with the system. To do this, we add the following configuration file to the directory /etc/systemd/system:

Let’s look at this fragment piece by piece. Under [Description] we enter the container name. Under [Service] we firstly set a limit on the permissible number of open files in the container (LimitNOFILE), then we enter the command to launch the container with the necessary options (ExecStart). Restart=always means the container should restart in the event of a crash. Under [Install] we given the additional unit that should be added to the host’s autolaunch (in our case, this is the inter-process communication system D-Bus).

We save our changes to the configuration file and run the following command:

There are other, less complicated ways to launch a container as a service. Systemd has a configuration file template for automatically launching containers saved in the /var/lib/machines directory. We can enable a launch based on this template with the following command:

Managing Containers: machinectl

Containers can be managed with the machinectl utility. We’ll take a brief look at its basic options.

To print a list of containers in the system:

To view information on a container’s status:

To log into a container:

To restart a container:

To turn off a container:

The last command will work if a systemd-compatible operating system is installed in the container. For operating systems using sysvinit, we have to use the terminate option.

We talked a bit about machinectl’s most basic features; for more detailed instructions, see here.

Uploading Images

We’ve already mentioned that systemd-spawn can be used to load images in a variety of formats. There is, however, one important thing to remember: only images built on btrfs can be used, which must be mounted to the /var/lib/machines directory:

If there are no disks available, Btrfs can write it to a file.

Docker Qcow2 Vs Raw Data

In newer versions of systemd, images can be uploaded out of the box without mounting Btrfs.

We upload a Docker image:

Afterwards, loading the container built on the uploaded image is simple:

Viewing Container Logs

Information on the events that occur in a container are recorded in a log. Logging can be configured when a container is created using the –link-journal option. For example:

This command means container logs will be saved on the main host in the directory /var/log/journal/machine-id. If we use the option –link-journal=guest, then all of the logs will be saved in the container in the /var/log/journal/machine-id directory, and a symbolic link will be created on the main host to the directory with the saved address. The option –link-journal will only work if the system launched in the container has systemd installed; if it doesn’t, there’s no guarantee that logging will work properly.

Information on the launch and shutdown of containers can be viewed using journalctl, which we wrote about in a previous article:

Journalctl can be used to view logs of container events. This is done using the -M option (we’ll display just a small fragment from the printout):

Limits on the resources containers can access may be recorded in the unit file or [Slice] section.

Docker Qcow2 Vs Raw Dog Food

Conclusion

Systemd-nspawn is an interesting and prospective tool. Among its obvious advantages, it’s worth noting:

• integration with different systemd components;
• compatibility with various image formats;
• self-contained; there’s no need to install extra packets or kernel patches.

Of course it’s too early to list all of systemd-nspawn’s potential uses for production: the tool is still fairly raw and can only be used for experimenting with. However, considering how widespread systemd is going to be, it’s worth waiting for a more complete systemd-nspawn.

Docker Mac Raw Vs Qcow2

It’d be impossible to write a complete overview here. You’re welcome to leave any questions or comment below.
If we overlooked any details or failed to mention an interesting feature of systemd-nspawn, please let us know and we’ll certainly add it to our review.
And if any of you use or have used systemd-nspawn, please share your experiences with us!