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




A Site JSON file describes the structure of a Site, aka virtual host. Generally, a Site:

  • has a certain hostname, such as, or * if the Site should respond to all requests regardless of HTTP host header;
  • has a single administrator, for which username, e-mail address etc. are given;
  • may or may not have SSL/TLS information (key, certificate etc.) so the Site can be served over HTTPS;
  • runs one or more Apps at different context paths, such as Wordpress at /blog, and a wiki at /wiki,
  • each of those Apps may be configured with any number of Accessories (for example, Wordpress plugins or themes), and
  • may also define certain well-known files, such as robots.txt.

UBOS captures all of this information in a single JSON file with a particular structure, called the Site JSON file. You can usually interact with Site JSON files as opaque blobs, but if you like to see the Site JSON file for a Site you have currently deployed, use the ubos-admin showsite command either with the Site’s hostname or SiteId:

% sudo ubos-admin showsite --json --hostname <hostname>


% sudo ubos-admin showsite --json --siteid <siteid>

If you run this command as a user other than root, no credential information will be included.

The easiest way of creating a Site JSON file is with the createsite command:

% sudo ubos-admin createsite -n -o newsite.json

(The -n flag will only generate the Site JSON and not deploy the Site; the -o newsite.json flag will save the generated Site JSON to file newsite.json.)


The Site JSON is a JSON hash with the following entries:

admin (required)
The admin section defines the administrator for the Site. It has the following entries:

userid (required) User identifier for the administrator. Example: admin.

username (required) Human-readable name for the administrator. Example: John Smith.

credential (required) Credential for the administrator account. Example: s3cr3t. Only shown to the root user.

email (required) Contact e-mail for the administrator. Example:

appconfigs (optional)
A JSON array of the AppConfigurations at this Site. There is no significance to the order of the elements in the array. An AppConfiguration is the deployment of an App at a particular Context Path at a particular Site, together with any Accessories and/or Customization Points that are specific to this deployment of the App.
hostname (required)
The hostname for the Site, or *. E.g.
lastupdated (optional)
timestamp for when this Site JSON file was last deployed to the current Device. This data element gets inserted or updated by UBOS in the Site JSON held on the Device every time a Site is deployed.
siteid (required)
The SiteId: a unique identifier for the Site. This is generally an s followed by 40 hex characters. E.g. s054257e710d12d7d06957d8c91ab2dc1b22d7b4c.
tls (optional)
This section is optional. If provided, UBOS will set up the Site to be only accessible via HTTPS. UBOS will also automatically redirect incoming HTTP requests to their HTTPS equivalent.
If true, obtain a certificate from LetsEncrypt, and set up the Site with it. Also start an automatic renewal process.
key (if not provided and not letsencrypt, auto-generate one)
The key for the tls Site. Only shown to the root user.
crt (if not provided and not letsencrypt, create a self-signed on)
The certificate for the tls Site as issued by your certificate authority, plus the certificate chain of your certificate authority, concatenated into one file. Only shown to the root user.
cacrt (optional)
If you use TLS client authentication (not common), the certificate chain of the certificate authorities that your TLS clients are using. Only shown to the root user.
tor (optional)
This section is optional. If it is given, this Site is intended to be run as a Tor hidden service.
privatekey (optional)
Contains the Tor private key, if it has been allocated already.
wellknown (optional)
This section is optional. It contains the data for “well-known” files that your Site may be using. In this section, each key-value pair represents an entry into the Site’s /.well-known/ Context Path, with the key being the name of the file and the value being a structure with the following potential members:
Static file content if there is; the value may be encoded.
If given, base64 is the only valid value. It indicates that the value of value is provided using Base64 encoding and needs to be decoded first. This is useful for entries such as favicon.ico.
HTTP status code to return when accessed. This may only be specified when a location is provided, and the value must be a HTTP redirect status code, such as “307”. When location is provided, the default is “307” (Temporary Redirect).
Value for an HTTP Redirect header when accessed. This is mutually exclusive with value: only one of these two may be provided.
Only permitted for an entry whose key is robots.txt and for which no value has been provided. See discussion below.

For all keys other than robots.txt, the values provided in the Site JSON override any values that may have been provided by the Apps deployed to that Site. Conversely, if the Site JSON does not specify a certain key, but an App deployed to this Site does, the App’s will be used (more details are described in UBOS Manifest). If multiple Apps define the same key, the value from the App defined earlier in the Site JSON’s list of AppConfigurations takes precedence over later ones.

If a value is provided for the key robots.txt, this value will be used. If not, the value for the robots.txt content is constructed by concatenating:

  • the value of prefix in the Site JSON, if such a value is given;

  • a catch-all User-Agent line

  • all Allow/Disallow statements specified by the Apps (more details are described in UBOS Manifest).

Note that UBOS will automatically make the content of the historic files robots.txt, favicon.ico and sitemap.xml available both at the root of the Site and in the .well-known sub-directory.


Each member of the appconfigs array is a JSON hash with the following entries:

appconfigid (required)
A unique identifier for the AppConfiguration. This is generally an a followed by 40 hex characters. E.g. a7d74fb881d43d12ff0ba4bd2ed39a98e107eab8c.
context (optional)
The context path, from the root of the Site, where the AppConfiguration will run. For example, if you want to run Wordpress at, the Context Path would be /blog (no trailing slash). If you want to run an App at the root of the Site, specify an empty string. If this field is not provided, UBOS will use the App’s default Context Path defined in the App’s UBOS Manifest.
isdefault (optional)
If provided, the value must be boolean true. This instructs UBOS to automatically redirect clients from the root page of the Site to this AppConfiguration. If not provided, UBOS will show the installed Apps at the root page of the Site.
appid (required)
The package identifier of the App to be run. For example: wordpress.
accessoryids (optional)
If provided, this entry must be a JSON array, containing one or more package identifiers of the Accessories to be run for this installation of the App. For example: [ 'wordpress-plugin-webmention' ]
customizationpoints (optional)
If provided, this entry must be a JSON hash, providing values for Customization points section of the App and/or Accessories at this AppConfiguration. They keys in this JSON hash are the package names of the packages installed at this AppConfiguration, i.e. the package name of the App, and any additional Accessories. (By doing this, there cannot be any namespace collisions between Customization Points defined in the App and the Accessory).

The value for each package is again a JSON hash, with the name of the Customization Point as the key, and a JSON hash as a value. Typically, this last JSON hash only has a single entry named value, whose value is the value of the Customization Point. For example:

"customizationpoints" : {
  "wordpress" : {
    "title" : {
      "value" : "My blog"