Bind Cannot Assign Requested Address Issue 2027 Docker For

  1. Bind Cannot Assign Requested Address Issue 2027 Docker For Ubuntu
  2. Bind Cannot Assign Requested Address Issue 2027 Docker For Windows

Can’t connect to the server running in your container? Let’s see why, and how to fix it, starting with an example.

If you run a server on your machine listening on 127.0.0.1, the “loopback” or “localhost” address:

You can then load it in your browser at http://127.0.0.1:8000.

I've used Syncthing in the past, but this is my first experience in using it as a docker under Unraid. The gui is showing the listeners as 0/1 (in red) with the following message ' tcp://10.0.30.xxx:22000: listen 10.0.30.xxx:22000: bind: cannot assign requested address' I've got 22000 assigned in the docker. I'm running a Ubuntu Server 16.04 box with Parallels Desktop virtual machine on a mac. I believe the versions of all these runtime environments have no impact on this issue. Fresh install Ubuntu box with docker installed apt install docker.io; run: sudo docker run -it -rm -p 2/udp roemer/bedrock-server, so far everything goes fine. So to confirm that memcached doesn't listen on any ports I ran 'docker ps -a', and this was the output: CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES 116acff4b1aa memcached 'docker-entrypoint.s'.

But if you kill that and run it in a container:

If you then try to connect with your browser to http://127.0.0.1:8000 you’ll get connection refused or connection reset.

What’s going on?To understand how to solve this, you need to know a minimal amount about how Docker’s networking works.In particular, this article will cover:

  • Networking namespaces, and how Docker uses them.
  • What docker run -p 5000:5000 does, and why our example above doesn’t work.
  • How to fix your image so the server is accessible.

Networking without Docker

Let’s start with our first scenario: you run a server directly inside your operating system, and then connect to it.I’m going to assume the main OS is Linux, for simplicity of explanation. Docker runs on non-Linux OSes like macOS by running a Linux virtual machine, but the practical consequences are the same.

Your operating system has multiple network “interfaces”.For example, on my computer (with output shortened for clarity):

In this output we see three network interfaces:

  • We’ll ignore docker0 for now.
  • lo is the loopback interface, with IPv4 address 127.0.0.1: it’s your own computer, addressable in-memory without any networking hardware.
  • wlp0s20u8 is my WiFi card, with IPv4 address 192.168.7.202, and when I talk to computers on the Internet the packets are sent via that interface.

Let’s go back to our starting, working example—you run a server listening on 127.0.0.1, and then connect to it.We can visualize it like this:

Network namespaces

You’ll notice the image above talks about a “Default network namespace”.So what’s that?

Docker is a system for running containers: a way to isolate processes from each other.It builds on a number of Linux kernel features, one of which is network namespaces—a way for different processes to have different network devices, IPs, firewall rules, and so on.

By default, each container run by Docker has its own network namespace, with its own IPs:

So this container has two interfaces, eth0 and lo, each with their own IP addresses.But because this is a different network namespace, these are different interfaces than the default namespace we saw above.

To make it clear what this means, let’s run the Flask server inside a Docker container, and then diagram the results:

The resulting network setup looks like this:

Now it’s clear why there’s a connection refused: the server is listening on 127.0.0.1 inside the container’s network namespace.The browser is connecting to 127.0.0.1 in the main, default network namespace.But those are different interfaces, so no connection is made.

How do we connect the two network namespaces? With Docker port-forwarding.

Docker run port-forwarding (is not enough)

If we run docker run with -p 5000:5000, it will forward from all interfaces where the Docker daemon is running (for our purposes, the main network namespace) to the external IP address of the containter.

To break it down explicitly: -p 5000:5000 means redirecting traffic from port 5000 on all interfaces in the main network namespace to the container’s port 5000 on its external interface.-p 8080:80 would redirect traffic from port 8080 on all interfaces in the main network namespace to port 80 on the container’s external interface. And so on.

Bind Cannot Assign Requested Address Issue 2027 Docker For Ubuntu

(We’re doing port 5000 specifically because that’s where our Docker image is listening, Flask’s default port.)

So let’s run a container, and then look at a diagram to visually see what that means:

And now we see the second problem: the server is listening on 127.0.0.1 inside the container network namespace, but the port forwarding is going to the external IP, 172.17.0.2.

Thus, a connection reset or refused.

Bind Cannot Assign Requested Address Issue 2027 Docker For Windows

The solution: listen on all interfaces

Port forwarding can only connect to a single destination—but you can change where the server process is listening.You do this by listening on 0.0.0.0, which means “listen on all interfaces”.

For example, you can do:

Note:--bind 0.0.0.0 is specifically an option for http.server; it’s not a Docker option.Other servers will have other ways of specifying this.For example, for a Flask application packaged with a Dockerfile, you can do:

Note: Outside the very specific topic under discussion, the Dockerfiles in this article are not examples of best practices, since the added complexity would obscure the main point of the article.

To ensure you’re writing secure, correct, fast Dockerfiles, consider my Python on Docker Production Handbook, which includes a packaging process and >70 best practices.

Now the network diagram looks like this:

Want to quickly get up to speed on Docker packaging? This article is an excerpt from my book, Just Enough DockerPackaging.

Takeaways

  1. By default, containers run in their own network namespaces, with their own IP addresses.
  2. docker run -p 5000:5000 will forward from all interfaces in the main network namespace (or more accurately, the one where the Docker daemon is running) to the external IP in the container.
  3. You therefore need to listen on the external IP inside the container, and the easiest way to do that is by listening on all interfaces: 0.0.0.0.

Estimated reading time: 16 minutes

Did you know that Docker Desktop now offers support for developers subscribed to a Pro or a Team plan? Click here to learn more.

This page contains information on how to diagnose and troubleshoot Docker Desktop issues, request Docker Desktop support (Pro and Team plan users only), send logs and communicate with the Docker Desktop team, use our forums and Success Center, browse and log issues on GitHub, and find workarounds for known problems.

Troubleshoot

Choose > Troubleshootfrom the menu bar to see the troubleshoot options.

The Troubleshoot page contains the following options:

  • Restart Docker Desktop: Select to restart Docker Desktop.

  • Support: Developers on Pro and Team plans can use this option to send a support request. Other users can use this option to diagnose any issues in Docker Desktop. For more information, see Diagnose and feedback and Support.

  • Reset Kubernetes cluster: Select this option to delete all stacks and Kubernetes resources. For more information, see Kubernetes.

  • Clean / Purge data: Select this option to delete container and image data. Choose whether you’d like to delete data from Hyper-V, WSL 2, or Windows Containers and then click Delete to confirm.

  • Reset to factory defaults: Choose this option to reset all options onDocker Desktop to their initial state, the same as when Docker Desktop was first installed.

Diagnose and feedback

In-app diagnostics

If you experience issues for which you do not find solutions in thisdocumentation, on Docker Desktop for Windows issues onGitHub, or the Docker Desktop for Windowsforum, we can help youtroubleshoot the log data. Before reporting an issue, we recommend that you read the information provided on this page to fix some common known issues.

  1. Choose > Troubleshootfrom the menu.
  2. Sign into Docker Desktop. In addition, ensure you are signed into your Docker account.
  3. Click Get support. This opens the in-app Support page and starts collecting the diagnostics.
  4. When the diagnostics collection process is complete, click Upload to get a Diagnostic ID.
  5. When the diagnostics have been uploaded, Docker Desktop prints a Diagnostic ID. Copy this ID.
  6. If you have subscribed to a Pro or a Team plan, click Contact Support. This opens the Docker Desktop support form. Fill in the information required and add the ID you copied earlier to the Diagnostics ID field. Click Submit to request Docker Desktop support.

    Note

    You must be signed in to Docker Desktop using your Pro or Team plan credentials to access the support form. For information on what’s covered as part of Docker Desktop support, see Support.

  7. If you are not subscribed to a Pro or a team plan, you can click Upgrade to benefit from Docker Support to upgrade your existing account. Alternatively, click Report a Bug to open a new Docker Desktop issue on GitHub. This opens Docker Desktop for Windows on GitHub in your web browser in a ‘New issue’ template. Complete the information required and ensure you add the diagnostic ID you copied earlier. Click submit new issue to create a new issue.

Diagnosing from the terminal

On occasions it is useful to run the diagnostics yourself, for instance ifDocker Desktop for Windows cannot start.

First locate the com.docker.diagnose, that should be in C:ProgramFilesDockerDockerresourcescom.docker.diagnose.exe.

To create and upload diagnostics in Powershell, run:

After the diagnostics have finished, you should have the following output,containing your diagnostic ID:

Troubleshooting topics

Make sure certificates are set up correctly

Docker Desktop ignores certificates listed under insecure registries, anddoes not send client certificates to them. Commands like docker run thatattempt to pull from the registry produces error messages on the command line,like this:

As well as on the registry. For example:

For more about using client and server side certificates, seeHow do I add custom CA certificates?and How do I add client certificates? in theGetting Started topic.

Volumes

Permissions errors on data directories for shared volumes

When sharing files from Windows, Docker Desktop sets permissions on shared volumesto a default value of 0777(read, write, execute permissions for user and for group).

The default permissions on shared volumes are not configurable. If you areworking with applications that require permissions different from the sharedvolume defaults at container runtime, you need to either use non-host-mountedvolumes or find a way to make the applications work with the default filepermissions.

See also,Can I change permissions on shared volumes for container-specific deployment requirements?in the FAQs.

Volume mounting requires shared folders for Linux containers

If you are using mounted volumes and get runtime errors indicating anapplication file is not found, access is denied to a volume mount, or a servicecannot start, such as when using Docker Compose,you might need to enable shared folders.

With the Hyper-V backend, mounting files from Windows requires shared folders for Linux containers. Click and then Settings > Shared Folders and share the folder that contains theDockerfile and volume.

Support for symlinks

Symlinks work within and across containers. To learn more, see How do symlinks work on Windows? in the FAQs.

Avoid unexpected syntax errors, use Unix style line endings for files in containers

Any file destined to run inside a container must use Unix style n lineendings. This includes files referenced at the command line for builds and inRUN commands in Docker files.

Docker containers and docker build run in a Unix environment, so files incontainers must use Unix style line endings: n, not Windows style: rn.Keep this in mind when authoring files such as shell scripts using Windowstools, where the default is likely to be Windows style line endings. Thesecommands ultimately get passed to Unix commands inside a Unix based container(for example, a shell script passed to /bin/sh). If Windows style line endingsare used, docker run fails with syntax errors.

For an example of this issue and the resolution, see this issue on GitHub:Docker RUN fails to execute shellscript.

Virtualization

Your machine must have the following features for Docker Desktop to function correctly.

WSL 2 and Windows Home

  1. Virtual Machine Platform
  2. Virtualization enabled in the BIOS
  3. Hypervisor enabled at Windows startup

Hyper-V

On Windows 10 Pro or Enterprise, you can also use Hyper-V with the following features enabled:

  1. Hyper-Vinstalled and working
  2. Virtualization enabled in the BIOS
  3. Hypervisor enabled at Windows startup

Docker Desktop requires Hyper-V as well as the Hyper-V Module for WindowsPowershell to be installed and enabled. The Docker Desktop installer enablesit for you.

Docker Desktop also needs two CPU hardware features to use Hyper-V: Virtualization and Second Level Address Translation (SLAT), which is also called Rapid Virtualization Indexing (RVI). On some systems, Virtualization must be enabled in the BIOS. The steps required are vendor-specific, but typically the BIOS option is called Virtualization Technology (VTx) or something similar. Run the command systeminfo to check all required Hyper-V features. See Pre-requisites for Hyper-V on Windows 10 for more details.

To install Hyper-V manually, see Install Hyper-V on Windows 10. A reboot is required after installation. If you install Hyper-V without rebooting, Docker Desktop does not work correctly.

From the start menu, type Turn Windows features on or off and press enter.In the subsequent screen, verify that Hyper-V is enabled.

Virtualization must be enabled

In addition to Hyper-V or WSL 2, virtualization must be enabled. Check thePerformance tab on the Task Manager:

If you manually uninstall Hyper-V, WSL 2 or disable virtualization,Docker Desktop cannot start. See Unable to run Docker for Windows onWindows 10 Enterprise.

Hypervisor enabled at Windows startup

If you have completed the steps described above and are still experiencingDocker Desktop startup issues, this could be because the Hypervisor is installed,but not launched during Windows startup. Some tools (such as older versions of Virtual Box) and video game installers disable hypervisor on boot. To reenable it:

  1. Open an administrative console prompt.
  2. Run bcdedit /set hypervisorlaunchtype auto.
  3. Restart Windows.

You can also refer to the Microsoft TechNet article on Code flow guard (CFG) settings.

Windows containers and Windows Server

Docker Desktop is not supported on Windows Server. If you have questions about how to run Windows containers on Windows 10, seeSwitch between Windows and Linux containers.

A full tutorial is available in docker/labs onGetting Started with Windows Containers.

You can install a native Windows binary which allows you to develop and runWindows containers without Docker Desktop. However, if you install Docker this way, you cannot develop or run Linux containers. If you try to run a Linux container on the native Docker daemon, an error occurs:

Running Docker Desktop in nested virtualization scenarios

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. It might workin some cases, and not in others.

For best results, we recommend you run Docker Desktop natively on a Windows system (to work with Windows or Linux containers), or on Mac to work with Linux containers.

If you still want to use nested virtualization

  • Make sure nested virtualization support is enabled in VMWare or Parallels.Check the settings in Hardware > CPU & Memory > Advanced Options > Enablenested virtualization (the exact menu sequence might vary slightly).

  • Configure your VM with at least 2 CPUs and sufficient memory to run yourworkloads.

  • Make sure your system is more or less idle.

  • Make sure your Windows OS is up-to-date. There have been several issues withsome insider builds.

  • The processor you have may also be relevant. For example, Westmere based MacPros have some additional hardware virtualization features over Nehalem basedMac Pros and so do newer generations of Intel processors.

Typical failures we see with nested virtualization

  • Slow boot time of the Linux VM. If you look in the logs and find some entriesprefixed with Moby. On real hardware, it takes 5-10 seconds to boot theLinux VM; roughly the time between the Connected log entry and the *Starting Docker ... [ ok ] log entry. If you boot the Linux VM inside aWindows VM, this may take considerably longer. We have a timeout of 60s or so.If the VM hasn’t started by that time, we retry. If the retry fails we printan error. You can sometimes work around this by providing more resources tothe Windows VM.

  • Sometimes the VM fails to boot when Linux tries to calibrate the time stampcounter (TSC). This process is quite timing sensitive and may fail whenexecuted inside a VM which itself runs inside a VM. CPU utilization is alsolikely to be higher.

  • Ensure “PMU Virtualization” is turned off in Parallels on Macs. Check thesettings in Hardware > CPU & Memory > Advanced Settings > PMUVirtualization.

Networking issues

IPv6 is not (yet) supported on Docker Desktop.

Workarounds

Reboot

Restart your PC to stop / discard any vestige of the daemon running from thepreviously installed version.

Unset DOCKER_HOST

The DOCKER_HOST environmental variable does not need to be set. If you usebash, use the command unset ${!DOCKER_*} to unset it. For other shells,consult the shell’s documentation.

Make sure Docker is running for webserver examples

For the hello-world-nginx example and others, Docker Desktop must berunning to get to the webserver on http://localhost/. Make sure that theDocker whale is showing in the menu bar, and that you run the Docker commands ina shell that is connected to the Docker Desktop Engine. Otherwise, you might start the webserver container but get a “web pagenot available” error when you go to docker.

How to solve port already allocated errors

If you see errors like Bind for 0.0.0.0:8080 failed: port is already allocatedor listen tcp:0.0.0.0:8080: bind: address is already in use ...

These errors are often caused by some other software on Windows using thoseports. To discover the identity of this software, either use the resmon.exeGUI and click “Network” and then “Listening Ports” or in a Powershell usenetstat -aon find /i 'listening ' to discover the PID of the processcurrently using the port (the PID is the number in the rightmost column). Decidewhether to shut the other process down, or to use a different port in yourdocker app.

Docker Desktop fails to start when anti-virus software is installed

Address

Some anti-virus software may be incompatible with Hyper-V and MicrosoftWindows 10 builds. The conflicttypically occurs after a Windows update andmanifests as an error response from the Docker daemon and a Docker Desktop start failure.

For a temporary workaround, uninstall the anti-virus software, orexplore other workarounds suggested on Docker Desktop forums.

Support

Docker Desktop offers support for developers subscribed to a Pro or a Team plan. Click here to upgrade your existing account.

This section contains instructions on how to get support, and covers the scope of Docker Desktop support.

How do I get Docker Desktop support?

If you have subscribed to a Pro and Team account, please raise a ticket through Docker Desktop support.

Docker Community users can get support through our Github repos for-win and for-mac, where we respond on a best-effort basis.

What support can I get?

If you are a Pro or a Team user, you can request for support on the following types of issues:

  • Desktop upgrade issues
  • Desktop installation issues
    • Enabling virtualization in BIOS
    • Enabling Windows features
    • Installation crashes
    • Failure to launch Docker Desktop on first run
  • Usage issues
    • Crash closing software
    • Docker Desktop not behaving as expected
  • Configuration issues
  • Basic product ‘how to’ questions such as ‘how to work efficiently on WSL 2’

What is not supported?

Docker Desktop excludes support for the following types of issues:

  • Use on or in conjunction with hardware or software other than that specified in the applicable documentation
  • Running on unsupported operating systems, including beta/preview versions of operating systems
  • Support for the Docker engine, Docker CLI, or other bundled Linux components
  • Support for Kubernetes
  • Features labeled as experimental
  • System/Server administration activities
  • Supporting Desktop as a production runtime
  • Scale deployment/multi-machine installation of Desktop
  • Routine product maintenance (data backup, cleaning disk space and configuring log rotation)
  • Third-party applications not provided by Docker
  • Altered or modified Docker software
  • Defects in the Docker software due to hardware malfunction, abuse, or improper use
  • Any version of the Docker software other than the latest version
  • Reimbursing and expenses spent for third-party services not provided by Docker
  • Docker Support excludes training, customization, and integration

What versions are supported?

We currently only offer support for the latest version of Docker Desktop. If you are running an older version, you may be asked to upgrade before we investigate your support request.

How many machines can I get support for Docker Desktop on?

As a Pro user you can get support for Docker Desktop on a single machine.As a Team, you can get support for Docker Desktop for the number of machines equal to the number of seats as part of your plan.

What OS’s are supported?

Docker Desktop is available for Mac and Windows. The supported version information can be found on the following pages:

Can I run Docker Desktop on Virtualized hardware?

No, currently this is unsupported and against the terms of use.

windows, troubleshooting, logs, issues