Policy settings

You can change policy settings to affect when 0install looks for updates and which versions it prefers.

The first part shows how to set policy settings that apply to all applications of the current user. The last section shows how to change per-application settings. Policy affects which versions 0install chooses (do you want test versions, ...).

General policy settings

LinuxWindows

You can change the policy settings using the Preferences dialog.

To open it run 0install config or choose Zero Install -> Manage Applications from the Applications menu, click on the edit properties icon next to an application and click Preferences.

You can change the policy settings using the Configuration dialog.

To open it run 0install-win config or click on the Options in the bottom left of the main GUI.

Administrators can pre-set and lock any of these settings using Windows Group Policy.

Network use

Affects how much 0install will rely on the network. Possible values are:

Value	Effect
Full	Normal network use.
Minimal	0install will prefer cached versions over non-cached ones.
Off-line	0install will not use the network.

Freshness

0install caches feeds and checks for updates from time to time. The freshness indicates how old a feed may get before 0install automatically checks for updates to it. Note that 0install only checks for updates when you actually run a program; so if you never run something, it won't waste time checking for updates.

Help test new versions

By default, 0install tries not to select new versions while they're still in the "testing" phase. If checked, 0install will instead always select the newest version, even if it's marked as "testing".

Kiosk mode

Restricts 0install to the applications listed in the registered catalogs, so that users of a managed machine cannot run arbitrary feeds of their own. Off by default. See Kiosk mode for how to enable and enforce it.

Windows Group Policy

On Windows, 0install reads settings from two registry keys in addition to its config files:

HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Zero Install
HKEY_CURRENT_USER\SOFTWARE\Policies\Zero Install

A machine policy takes precedence over a user policy, and both take precedence over any config file. A setting that is present in either key is also locked: 0install config and the Configuration dialog refuse to change it.

0install ships an ADMX template so the settings appear in the Group Policy editor. Get 0install.admx and *\0install.adml and copy them into either

• %WINDIR%\PolicyDefinitions on a single machine, or
• \\<domain>\SYSVOL\<domain>\Policies\PolicyDefinitions for the domain Central Store

The settings then show up under Computer Configuration → Administrative Templates → Zero Install and under User Configuration for the per-user variant.

Setting values directly

If you provision the registry yourself, write the values under the policy key using the same names 0install uses in its config file:

Value name	Type	Notes
network_use	REG_SZ	full, minimal or off-line
freshness	REG_DWORD	In seconds. 604800 is one week.
help_with_testing	REG_DWORD	1 or 0
auto_approve_keys	REG_DWORD	1 or 0
max_parallel_downloads	REG_DWORD	1 to 128
feed_mirror	REG_SZ	Empty string disables the feed mirror.
key_info_server	REG_SZ	Empty string disables the key information server.
self_update_uri	REG_SZ	Empty string disables self-update.
prefer_sat_solver	REG_DWORD	1 or 0
sync_server	REG_SZ	See Sync.
sync_server_user	REG_SZ
sync_server_pw	REG_SZ	Stored as plain text; see the warning below.
sync_server_kerberos	REG_DWORD	1 or 0
sync_crypto_key	REG_SZ	Stored as plain text; see the warning below.
kiosk_mode	REG_DWORD	1 or 0. See Kiosk mode.

Booleans accept either a REG_DWORD of 1 / 0 or a REG_SZ of True / False.

Attention

sync_server_pw and sync_crypto_key are read from the registry verbatim. In the config file these are stored base64-encoded (as sync_server_pw_base64 and sync_crypto_key_base64), but that is obfuscation rather than encryption and does not apply here at all. Anyone who can read the policy key can read these values. Prefer sync_server_kerberos for authentication, and deploy per-user secrets by another route.

Tip

To check what a machine actually ended up with, run 0install config with no arguments. It prints the effective value of every setting, including the ones coming from group policy.

Per-application policy settings

You can change per-application policy settings in the application information dialog. To open this dialog:

LinuxWindows

1. Run 0install run with the --gui option and the URI of the application:

   0install run --gui http://rox.sourceforge.net/2005/interfaces/Edit
   

   -or-

   Choose Zero Install -> Manage Applications from the Applications menu, click on the edit properties icon next to the application.
   

2. Double-click the application in the list. For example, double-clicking on Edit displays this dialog box:
   
   

1. Run 0install run with the --customize option and the URI of the application:

   0install run --customize https://apps.0install.net/gui/vlc.xml
   

   -or-

   In the main GUI open the dropdown menu next to an App's Run button, select Run with options, set the Customize version checkbox and click OK.
   

2. Click on the Change link next to the application. This displays this dialog box:
   

Feeds

In the Feeds tab, a list of feeds shows all the places where Zero Install looks for versions of the app. By default, there is just one feed with the URL you just entered. You can register additional feeds to be considered (e.g., a local feed with custom builds or an alternate remote feed). This can be done either using the GUI or with the 0install add-feed command.

Versions

In the Versions tab, you can use the Preferred Stability setting in the interface dialog to choose which versions to prefer. You can also change the stability rating of any implementation by clicking on it and choosing a new rating from the popup menu (drop-down in the Override column on Windows). User-set ratings are shown in capitals.

As you make changes to the policy and ratings, the selected implementation will change. The version shown in bold (or at the top of the list, in some versions) is the one that will actually be used. In addition to the ratings below, you can set the rating to Preferred. Such versions are always preferred above other versions, unless they're not cached and you are in Off-line mode.

The following stability ratings are allowed:

• Stable (this is the default if Help test new versions is unchecked)
• Testing (this is the default if Help test new versions is checked)
• Developer
• Buggy
• Insecure

Stability ratings are kept independently of the implementations, and are expected to change over time. When any new release is made, its stability is initially set to Testing. If you have selected Help test new versions in the Preferences dialog box then you will then start using it. Otherwise, you will continue with the previous stable release. After a while (days, weeks or months, depending on the project) with no serious problems found, the author will change the implementation's stability to Stable so that everyone will use it.

If problems are found, it will instead be marked as Buggy, or Insecure. Neither will be selected by default, but it is useful to see the reason (you might opt to continue using a buggy version if it works for you, but should never use an insecure one). Developer is like a more extreme version of Testing, where the program is expected to have bugs.

Tip

If you want to use the second item on the list because the first is buggy, for example, then it is better to mark the first version as buggy than to mark the second as preferred. This is because when a new version is available, you will want that to become the version at the top of the list, whereas a preferred version will always be first.