Documentation Overview

  1. Operation documentation
    1. Installation
      1. Run UBOS on a PC (64bit)
      2. Run UBOS from a boot stick on a PC (64bit)
      3. Run UBOS in a VirtualBox virtual machine (64bit)
      4. Run UBOS on an Amazon Web Services EC2 virtual server
      5. Run UBOS on Raspberry Pi 5
      6. Run UBOS on ESPRESSObin
      7. Run UBOS in a Linux container on a PC (64bit)
      8. Run UBOS in an aarch64 Linux container
    2. Setting up your first Site and App
    3. Setting up networking and DNS
    4. How to create a website secured by SSL/TLS
    5. How to set up a website as a Tor hidden service
    6. Managing Sites and Apps
    7. Backup and restore
    8. Upgrading and keeping UBOS current
    9. The UBOS Staff
    10. App-specific notes
      1. Reliably send e-mail via Amazon Web Services’ Simple E-mail Service: amazonses
      2. Static website hosting with rsync-based upload: docroot
      3. Notes on Mastodon
      4. Notes on Nextcloud
      5. Notes on Redirect
      6. Notes on Wordpress
    11. Device-specific Notes
      1. ESPRESSObin
      2. Raspberry Pi
    12. Advanced management
      1. Enabling non-standard package repositories
      2. Migrating from one App to another
      3. Pinning resources
    13. Command reference
    14. FAQ, HOWTOs and Troubleshooting
      1. “Package not found error” when installing a new App or Accessory
      2. A UBOS container comes up degraded
      3. Booting UBOS on a PC starts out fine, but then the screen goes blank
      4. Can I run UBOS in a Docker container?
      5. Can I use UBOS without purchasing a domain name?
      6. Cannot access MySQL database. File missing: /etc/mysql/root-defaults-ubos.cnf
      7. Cannot boot UBOS from boot stick on a PC
      8. Cannot connect to the public internet from a UBOS container
      9. Cannot create a temporary backup; the backup directory is not empty
      10. Failed to create file /sys/devices/system/cpu/microcode/reload
      11. How are the various UBOS images different from each other?
      12. How can I install more than one web App on the same Device?
      13. How do I set up WiFi?
      14. How to enable non-standard Package Repositories
      15. How to get help
      16. How to log into your UBOS Device
      17. How to modify the configuration of your Site
      18. How to report a bug or issue
      19. How to use Pagekite to reach your UBOS Device behind a firewall
      20. How to use SSH
      21. I need a Package that isn’t in UBOS
      22. I need root
      23. I own a domain name, and I’d like to use it for my UBOS Device. How do I do that?
      24. I want to move from one device to another, or from/to the cloud to/from a device
      25. I want to run ssh on a non-standard port
      26. I’m running out of disk space, what now?
      27. Installing a new Package or updating fails with a message about “invalid or corrupted package” or “key is disabled”
      28. Installing a new Package or upgrading fails with a message about “unknown trust”
      29. Is it safe to have my Site accessible from the public web?
      30. My non-English keyboard layout is all screwed up
      31. My SD card is much larger than the UBOS image. How do I use the rest of the space?
      32. Nothing happens when UBOS is supposed to be booting
      33. Problems with “IPv6 Packet Filtering Framework”
      34. UBOS is in a “degraded” state
      35. ubos-admin status reports “Systemd unit … has failed”
      36. Verify your downloaded UBOS image
      37. What is the default “root” password?
      38. What text editor can I use on UBOS?
      39. Why did you derive UBOS Linux from Arch Linux, and what is the relationship between UBOS Linux and Arch?
      40. Why is it called UBOS?
      41. Writing a disk image to a USB stick or SD card
        1. Writing an image to a USB stick or SD card on Linux
        2. Writing an image to a USB stick or SD card on macOS
        3. Writing an image to a USB stick or SD card on Windows
  2. Developer documentation
    1. Developer setup
      1. Developing using Arch Linux on VirtualBox x86_64 with a systemd-nspawn container
      2. Developing using a UTM Arch Linux VM on Apple Silicon computers with UBOS in a systemd-nspawn container
      3. Alternate developer setups
        1. Developing using a systemd-nspawn container (Linux host only)
        2. Developing using Arch Linux using Parallels on Apple Silicon with a systemd-nspawn container
        3. Developing using a UTM Arch Linux VM on Apple x86_64 computers with UBOS in a systemd-nspawn container
    2. Developer tutorials for standalone UBOS apps (not UBOS Mesh)
      1. Build and run your first UBOS standalone App
      2. How to package UBOS standalone Apps built with a variety of languages
        1. Hello World
        2. Glad-I-Was-Here (PHP, Mariadb)
        3. An Accessory for Glad-I-Was-Here (PHP, Mariadb)
        4. Glad-I-Was-Here (PHP, Postgresql)
        5. Glad-I-Was-Here (Python, Mariadb)
    3. UBOS Gears Reference
      1. UBOS Manifest
        1. Structure of the UBOS Manifest
        2. Info section
        3. Roles section
        4. Customization points section
        5. Appinfo section
        6. Accessoryinfo section
        7. Variables available at deploy or undeploy
        8. Functions that may be applied to variables
        9. Creating random values
        10. Scripts in UBOS Manifests
      2. Site JSON
      3. A complex deployment example
      4. UBOS Networking
      5. Allocating and opening up non-default ports
      6. Logging
      7. UBOS state
      8. UBOS Backup format
      9. Format of the App Status JSON
      10. Testing standalone Apps with “webapptest”
      11. Understanding ubos-admin
        1. Command: ubos-admin backup
        2. Command: ubos-admin backupinfo
        3. Command: ubos-admin createsite
        4. Command: ubos-admin deploy
        5. Command: ubos-admin hostid
        6. Command: ubos-admin init-staff
        7. Command: ubos-admin list-data-transfer-protocols
        8. Command: ubos-admin listnetconfigs
        9. Command: ubos-admin listsites
        10. Command: ubos-admin read-configuration-from-staff
        11. Command: ubos-admin restore
        12. Command: ubos-admin setnetconfig
        13. Command: ubos-admin setup-shepherd
        14. Command: ubos-admin showappconfig
        15. Command: ubos-admin shownetconfig
        16. Command: ubos-admin showsite
        17. Command: ubos-admin status
        18. Command: ubos-admin undeploy
        19. Command: ubos-admin update
        20. Command: ubos-admin write-configuration-to-staff
    4. Release channels and UBOS release process
    5. Miscellaneous
      1. Potentially useful infrastructure for standalone Apps
        1. The UBOS rsync server
      2. Middleware-specific notes
        1. Node.js notes
        2. SMTP notes
      3. Setting up an Arch Linux system as a UBOS development system
        1. How to create a UBOS development VM for VirtualBox on x86_64
        2. How to create a UBOS development VM for UTM on x86_64 Apple computers
        3. How to create a UBOS development VM for UTM on Apple Silicon computers
        4. How to create a UBOS development VM for Parallels Desktop on Apple Silicon computers
      4. Creating cloud images
        1. Amazon Web Services EC2
    6. Developer FAQ
      1. Doesn’t apt / dpkg / yum / pacman etc. does what UBOS Gears does already?
      2. Doesn’t puppet / chef / ansible etc. does what UBOS Gears does already?
      3. Doesn’t Docker do what UBOS Gears does already?
      4. Is it possible to run UBOS Gears or Mesh on an operating system other than UBOS Linux?
      5. Can I manage apps packaged as Docker containers with UBOS?
  3. Architecture
  4. Glossary
    1. Accessory
    2. App
    3. AppConfigId
    4. AppConfigItem
    5. AppConfiguration
    6. Arch
    7. Arch Linux
    8. Attribute
    9. blessing
    10. Bot
    11. Context Path
    12. Customization Point
    13. Data Transfer Protocol
    14. Deployment
    15. Depot
    16. Device
    17. Device Class
    18. diet4j module framework
    19. EntityType
    20. Flock
    21. Gradle
    22. Handlebars
    23. History
    24. Home Server
    25. HostId
    26. Hostname
    27. IDE
    28. Installation
    29. LetsEncrypt
    30. mDNS
    31. MeshBase
    32. MeshObject
    33. MeshObjectIdentifier
    34. MeshType
    35. MeshTypeIdentifier
    36. Middleware
    37. Model
    38. Network Configuration
    39. Package
    40. Pagekite
    41. Parallels Desktop
    42. Personal Server
    43. PKGBUILD
    44. Property
    45. PropertyType
    46. Relationship
    47. RelationshipType
    48. Release Channel
    49. Repository
    50. Retention Bucket
    51. Role
    52. RoleAttribute
    53. RoleProperty
    54. RoleType
    55. Rolling Release
    56. Shepherd
    57. Site
    58. Site JSON
    59. Site JSON Template
    60. SiteId
    61. Transaction
    62. Transaction Log
    63. UBOS Gears
    64. UBOS Linux
    65. UBOS Manifest
    66. UBOS Mesh
    67. UBOS Mesh code generator
    68. UBOS Project
    69. UBOS Staff
    70. unblessing
    71. UTM
    72. VirtualBox
    73. VMWare
    74. Wildcard hostname

Developing using a systemd-nspawn container (Linux host only)



This should work on all 64-bit x86_64 Linux systems that run systemd – that’s most of them at this point – and most (all?) 64-bit ARM Linux systems that run systemd. We have tested this setup on Arch Linux on x86_64 and aarch64 and with Ubuntu on x86_64.

If you use ARM, replace all occurrences of x86_64 in URLs and filenames in this document with aarch64.

Here are the steps:

Make sure systemd-nspawn is installed

Some Linux distros keep this systemd executable in a separate package that you need to first install. For example, on Ubuntu, install it with:

% sudo apt install systemd-container

Optional: btrfs filesystem

systemd-nspawn has built-in extra features when you use the btrfs filesystem. This can make container management much faster and take up less disk space. If you can, we recommend a btrfs partition; if not, that’s fine, too, it will work just fine on other filesystems as well.

Make sure your host allows Linux containers to access the internet

How to do this highly dependent on your networking setup. Here is a setup that works for us on Arch Linux, using systemd-networkd for network management. There are two steps:

  1. Run both IPv4 and IPv6 based iptables on your host, otherwise the UBOS container cannot set up its own firewall and UBOS containers will boot into a degraded state. (That’s not fatal, it just looks ugly and you might not see other problems as easily.) If you aren’t already doing this, on the host:

    % [[ -e /etc/iptables/iptables.rules ]] || sudo cp /etc/iptables/empty.rules /etc/iptables/iptables.rules
    % [[ -e /etc/iptables/ip6tables.rules ]] || sudo cp /etc/iptables/empty.rules /etc/iptables/ip6tables.rules
    % sudo systemctl enable --now iptables ip6tables

    This will not actually perform any firewall functionality (the ruleset is empty, unless you set some yourself), but it will allow the UBOS container to set up its own firewall.

  2. Make sure your host network interface forwards traffic from the the containers. Add IPForward=1 to the relevant .network file so IP packets will be forwarded from the container to the public internet (e.g. for package downloads). For example, /etc/systemd/networkd/ should read as follows:


    After you make a change to a .network file:

    % sudo systemctl daemon-reload
    % sudo systemctl restart systemd-networkd systemd-resolved

Pick a project directory

We recommend you do all your UBOS-related development below a certain directory. Let’s say that directory is ~/ubosdev-nspawn. Create that directory and enter it:

% mkdir ~/ubosdev-nspawn
% cd ~/ubosdev-nspawn

Then create a sub-directory for your project files:

% mkdir projects

Pick a release channel to work on

By default, this setup uses the yellow Release Channel. This is the recommended Release Channel for most application development.


If you want to develop on a Release Channel other than yellow, replace the string yellow with the name of the alternate Release Channel in all commands below.

Download a container image

Download a container image. Go to and look for the file ubos-develop_yellow_x86_64-container_LATEST.tar.xz.

If you chose a ${CHANNEL} other than yellow, replace the yellow in the above URL, and then the yellow in the filename with the name of the ${CHANNEL} you chose. Also remember to replace x86_64 with aarch64 if you are on ARM.

We will call the name of the downloaded image file ${IMAGE}. Download it into your working directory.

Unpack the container image

If your filesystem is btrfs, create a subvolume that becomes the filesystem for your container:

% sudo btrfs subvol create ubos-develop-yellow

For all other filesystems, simply create a directory that becomes the filesystem for your container:

% mkdir ubos-develop-yellow

Then unpack:

% ( cd ubos-develop-yellow; sudo tar xfJ ../ubos-develop_yellow_x86_64-container_LATEST.tar.xz )

Start the container

In the project directory, run:

% sudo systemd-nspawn -b -n -M ubos-develop-yellow -D ubos-develop-yellow \
   --bind $(pwd)/projects:/home/ubosdev/projects --bind $HOME/.m2:/home/ubosdev/.m2 --bind /dev/fuse \
   --network-zone ubos-yellow


This is a mouthful. You can create yourself a shortcut of you like:

% echo sudo systemd-nspawn -b -n -M ubos-develop-yellow -D ubos-develop-yellow \
   --bind $(pwd)/projects:/home/ubosdev/projects --bind $HOME/.m2:/home/ubosdev/.m2 --bind /dev/fuse \
   --network-zone ubos-yellow \
   > start-container-yellow
% chmod 755 start-container-yellow

and run it as:

% ./start-container-yellow

If your filesystem is btrfs, you can also add flag -x to this invocation. When you do, systemd-nspawn will make all changes in a temporary filesystem instead, and when you quit your container, your unpacked “directory” will still be unchanged.

Open a shell in the container

The shell in which you ran the systemd-nspawn command now shows a login prompt. You can login there as root (with this password, but if you do, we recommend you only use this shell to follow the system log, e.g. with journalctl -f).

To do your development, open up a separate shell and execute:

% sudo machinectl shell ubosdev@ubos-develop-yellow

This essentially does the same thing as if you were to log into your container as user ubosdev from the console or via ssh, but you don’t need to have any credentials set up.

You will execute your build commands in this shell. You can open up as many shells in the container as you like.

Note that your projects directory on the host that you created earlier, is mounted into your container right where you are. You can see the same files there on the host and in the container:

% ls -al projects

That makes sharing files between the host (where you can edit them with the editor of your choice) and the container (where you build and run your code) quite easy.

Shut down the container

When you are done developing, shut down the container with:


(three control-]’s, in a rapid sequence) in the shell that you ran systemd-nspawn in.