docker-documentation/FAQ.md

FAQ

Here will some Frequently Asked Questions reside

My host is incompatible with images based on Ubuntu Jammy

Some x86_64 hosts running older versions of the Docker engine are not compatible with some images based on Ubuntu Jammy.

Symptoms

If your host is affected you may see errors in your containers such as:

ERROR - Unable to determine java version; make sure Java is installed and callable

Or

Failed to create CoreCLR, HRESULT: 0x80070008

Or

WARNING :: MAIN : webStart.py:initialize:249 : can't start new thread

Resolution

Option 1 (Long-Term Fix)

Upgrade your Docker engine install to at least version 20.10.10. Refer to the official Docker docs for installation/update details.

Option 2 (Short-Term Fix)

For Docker CLI, run your container with:

--security-opt seccomp=unconfined

For Docker Compose, run your container with:

    security_opt:
      - seccomp=unconfined

My host is incompatible with images based on rdesktop

Some x86_64 hosts have issues running rdesktop based images even with the latest docker version due to syscalls that are unknown to docker.

Symptoms

If your host is affected you may see errors in your containers such as:

Failed to close file descriptor for child process (Operation not permitted)

Resolution

For Docker CLI, run your container with:

--security-opt seccomp=unconfined

For Docker Compose, run your container with:

    security_opt:
      - seccomp=unconfined

My host is incompatible with images based on Ubuntu Focal and Alpine 3.13 and later

This only affects 32 bit installs of distros based on Debian Buster.

This is due to a bug in the libseccomp2 library (dependency of Docker itself), which is fixed. However it's not pushed to all the repositories.

A GitHub issue tracking this

You have a few options as noted below. Options 1 is short-term, while option 2 is considered the best option if you don't plan to reinstall the device (option 3).

Resolution

If you decide to do option 1 or 2, you should just need to restart the container after confirming you have libseccomp2.4.4 installed.

If 1 or 2 did not work, ensure your Docker install is at least version 20.10.0, refer to the official Docker docs for installation.

Option 1

Manually install an updated version of the library with dpkg.

wget http://ftp.us.debian.org/debian/pool/main/libs/libseccomp/libseccomp2_2.4.4-1~bpo10+1_armhf.deb
sudo dpkg -i libseccomp2_2.4.4-1~bpo10+1_armhf.deb

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Option 2

Add the backports repo for DebianBuster. As seen here.

sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 04EE7237B7D453EC 648ACFD622F3D138
echo "deb http://deb.debian.org/debian buster-backports main" | sudo tee -a /etc/apt/sources.list.d/buster-backports.list
sudo apt update
sudo apt install -t buster-backports libseccomp2

Option 3

Reinstall/update your OS to a version that still gets updates.

• Any distro based on DebianStretch does not seem to have this package available
• DebianBuster based distros can get the package trough backports, as outlined in point 2.

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Symptoms

• 502 errors in Jellyfin as seen in linuxserver/docker-jellyfin#71
• Error starting framework core messages in the docker log for Plex. linuxserver/docker-plex#247
• No WebUI for Radarr, even though the container is running. linuxserver/docker-radarr#118
• Images based on our Nginx base-image(Nextcloud, SWAG, Nginx, etc.) fails to generate a certificate, with a message similar to error getting time:crypto/asn1/a_time.c:330
• docker exec <container-name> date returns 1970

I want to reverse proxy a application which defaults to https with a selfsigned certificate

Traefik

In this example we will configure a serverTransport rule we can apply to a service, as well as telling Traefik to use https on the backend for the service.

Create a ServerTransport in your dynamic Traefik configuration, we are calling ours ignorecert.

    http:
    serversTransports:
        ignorecert:
            insecureSkipVerify: true

Then on our foo service we tell it to use this rule, as well as telling Traefik the backend is running on https.

    - traefik.http.services.foo.loadbalancer.serverstransport=ignorecert
    - traefik.http.services.foo.loadbalancer.server.scheme=https