GNOME Software Reference Manual

+ + GNOME Software is a software installer designed to be easy to use. + + +

+ Introduction + + At the heart of gnome software the application is just a plugin loader + that has some GTK UI that gets created for various result types. + The idea is we have lots of small plugins that each do one thing and + then pass the result onto the other plugins. + These are ordered by dependencies against each other at runtime and + each one can do things like editing an existing application or adding a + new application to the result set. + This is how we can add support for things like firmware updating, + GNOME Shell web-apps and flatpak bundles without making big + changes all over the source tree. + + + There are broadly 3 types of plugin methods: + + + + Actions: Do something on a specific GsApp + + + Refine: Get details about a specific GsApp + + + Adopt: Can this plugin handle this GsApp + + + + In general, building things out-of-tree isn't something that I think is + a very good idea; the API and ABI inside gnome-software is still + changing and there's a huge benefit to getting plugins upstream where + they can undergo review and be ported as the API adapts. + I'm also super keen to provide configurability in GSettings for doing + obviously-useful things, the sort of thing Fleet Commander can set for + groups of users. + + + However, now we're shipping gnome-software in enterprise-class distros + we might want to allow customers to ship their own plugins to make + various business-specific changes that don't make sense upstream. + This might involve querying a custom LDAP server and changing the + suggested apps to reflect what groups the user is in, or might involve + showing a whole new class of applications that does not conform to the + Linux-specific application is a desktop-file paradigm. + This is where a plugin makes sense. + + + + The plugin needs to create a class derived from GsPlugin, + and define the vfuncs that it needs. The + plugin name is taken automatically from the suffix of the + .so file. The type of the plugin is exposed to + gnome-software using gs_plugin_query_type(), which + must be exported from the module. + + + A sample plugin + +/* + * Copyright (C) 2016 Richard Hughes + */ + +#include <glib.h> +#include <gnome-software.h> + +struct _GsPluginSample { + GsPlugin parent; + + /* private data here */ +}; + +G_DEFINE_TYPE (GsPluginSample, gs_plugin_sample, GS_TYPE_PLUGIN) + +static void +gs_plugin_sample_init (GsPluginSample *self) +{ + GsPlugin *plugin = GS_PLUGIN (self); + + gs_plugin_add_rule (plugin, GS_PLUGIN_RULE_RUN_BEFORE, "appstream"); +} + +static void +gs_plugin_sample_list_apps_async (GsPlugin *plugin, + GsAppQuery *query, + GsPluginListAppsFlags flags, + GCancellable *cancellable, + GAsyncReadyCallback callback, + gpointer user_data) +{ + GsPluginSample *self = GS_PLUGIN_SAMPLE (plugin); + g_autoptr(GTask) task = NULL; + const gchar * const *keywords; + g_autoptr(GsAppList) list = gs_app_list_new (); + + task = gs_plugin_list_apps_data_new_task (plugin, query, flags, + cancellable, callback, user_data); + g_task_set_source_tag (task, gs_plugin_sample_list_apps_async); + + if (query == NULL || + gs_app_query_get_keywords (query) == NULL || + gs_app_query_get_n_properties_set (query) != 1) { + g_task_return_new_error (task, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED, + "Unsupported query"); + return; + } + + keywords = gs_app_query_get_keywords (query); + + for (gsize i = 0; keywords[i] != NULL; i++) { + if (g_str_equal (keywords[i], "fotoshop")) { + g_autoptr(GsApp) app = gs_app_new ("gimp.desktop"); + gs_app_add_quirk (app, GS_APP_QUIRK_IS_WILDCARD); + gs_app_list_add (list, app); + } + } + + g_task_return_pointer (task, g_steal_pointer (&list), g_object_unref); +} + +static GsAppList * +gs_plugin_sample_list_apps_finish (GsPlugin *plugin, + GAsyncResult *result, + GError **error) +{ + return g_task_propagate_pointer (G_TASK (result), error); +} + +static void +gs_plugin_sample_class_init (GsPluginSampleClass *klass) +{ + GsPluginClass *plugin_class = GS_PLUGIN_CLASS (klass); + + plugin_class->list_apps_async = gs_plugin_sample_list_apps_async; + plugin_class->list_apps_finish = gs_plugin_sample_list_apps_finish; +} + +GType +gs_plugin_query_type (void) +{ + return GS_TYPE_PLUGIN_SAMPLE; +} + + + + + We have to define when our plugin is run in reference to other plugins, + in this case, making sure we run before appstream. + As we're such a simple plugin we're relying on another plugin to run + after us to actually make the GsApp complete, + i.e. loading icons and setting a localised long description. + + + In this example we want to show GIMP as a result (from any provider, + e.g. flatpak or a distro package) when the user searches exactly for + fotoshop. + + + We can then build and install the plugin using: + + + +gcc -shared -o libgs_plugin_example.so gs-plugin-example.c -fPIC \ + $(pkg-config --libs --cflags gnome-software) \ + -DI_KNOW_THE_GNOME_SOFTWARE_API_IS_SUBJECT_TO_CHANGE && \ +cp libgs_plugin_example.so $(pkg-config gnome-software --variable=plugindir) + + + + + + + + + +

+ +

+ Distribution Specific Functionality + + Some plugins should only run on specific distributions, for instance + the fedora-pkgdb-collections plugin should only be used on + Fedora systems. + This can be achieved with a simple runtime check using the helper + gs_plugin_check_distro_id() method or the GsOsRelease + object where more complicated rules are required. + + + Self disabling on other distributions + +static void +gs_plugin_sample_init (GsPluginSample *self) +{ + GsPlugin *plugin = GS_PLUGIN (self); + + if (!gs_plugin_check_distro_id (plugin, "ubuntu")) { + gs_plugin_set_enabled (plugin, FALSE); + return; + } + /* set up private data etc. */ +} + + + +

+ +

+ Custom Applications in the Installed List + + Next is returning custom applications in the installed list. + The use case here is a proprietary software distribution method that + installs custom files into your home directory, but you can use your + imagination for how this could be useful. + The example here is all hardcoded, and a true plugin would have to + derive the details about the GsApp, for example reading in an XML + file or YAML config file somewhere. + + + Example showing a custom installed application + +static void +gs_plugin_sample_init (GsPluginSample *self) +{ + GsPlugin *plugin = GS_PLUGIN (self); + + gs_plugin_add_rule (plugin, GS_PLUGIN_RULE_RUN_BEFORE, "icons"); +} + +static void +gs_plugin_custom_list_apps_async (GsPlugin *plugin, + GsAppQuery *query, + GsPluginListAppsFlags flags, + GCancellable *cancellable, + GAsyncReadyCallback callback, + gpointer user_data) +{ + g_autofree gchar *fn = NULL; + g_autoptr(GsApp) app = NULL; + g_autoptr(GIcon) icon = NULL; + g_autoptr(GsAppList) list = gs_app_list_new (); + g_autoptr(GTask) task = NULL; + + task = g_task_new (plugin, cancellable, callback, user_data); + g_task_set_source_tag (task, gs_plugin_custom_list_apps_async); + + /* We’re only listing installed apps in this example. */ + if (query == NULL || + gs_app_query_get_is_installed (query) != GS_APP_QUERY_TRISTATE_TRUE || + gs_app_query_get_n_properties_set (query) != 1) { + g_task_return_new_error (task, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED, + "Unsupported query"); + return; + } + + /* check if the app exists */ + fn = g_build_filename (g_get_home_dir (), "chiron", NULL); + if (!g_file_test (fn, G_FILE_TEST_EXISTS)) { + g_task_return_pointer (task, g_steal_pointer (&list), g_object_unref); + return; + } + + /* the trigger exists, so create a fake app */ + app = gs_app_new ("chiron.desktop"); + gs_app_set_management_plugin (app, plugin); + gs_app_set_kind (app, AS_COMPONENT_KIND_DESKTOP_APP); + gs_app_set_state (app, GS_APP_STATE_INSTALLED); + gs_app_set_name (app, GS_APP_QUALITY_NORMAL, "Chiron"); + gs_app_set_summary (app, GS_APP_QUALITY_NORMAL, "A teaching application"); + gs_app_set_description (app, GS_APP_QUALITY_NORMAL, + "Chiron is the name of an application.\n\n" + "It can be used to demo some of our features"); + + /* these are all optional, but make details page looks better */ + gs_app_set_version (app, "1.2.3"); + gs_app_set_size_installed (app, GS_SIZE_TYPE_VALID, 2 * 1024 * 1024); + gs_app_set_size_download (app, GS_SIZE_TYPE_VALID, 3 * 1024 * 1024); + gs_app_set_origin_hostname (app, "http://www.teaching-example.org/"); + gs_app_add_category (app, "Game"); + gs_app_add_category (app, "ActionGame"); + gs_app_add_kudo (app, GS_APP_KUDO_INSTALLS_USER_DOCS); + gs_app_set_license (app, GS_APP_QUALITY_NORMAL, "GPL-2.0+ and LGPL-2.1+"); + + /* use a stock icon */ + icon = g_themed_icon_new ("input-gaming"); + gs_app_add_icon (app, icon); + + /* return new app */ + gs_app_list_add (list, app); + + g_task_return_pointer (task, g_steal_pointer (&list), g_object_unref); +} + +static GsAppList * +gs_plugin_custom_list_apps_finish (GsPlugin *plugin, + GAsyncResult *result, + GError **error) +{ + return g_task_propagate_pointer (G_TASK (result), error); +} + + + + This shows a lot of the plugin architecture in action. Some notable points: + + + + + Setting the management plugin means we can check for this string + when working out if we can handle the install or remove action. + + + + + Most applications want a kind of AS_COMPONENT_KIND_DESKTOP_APP + to be visible as an application. + + + + + The origin is where the application originated from — usually + this will be something like Fedora Updates. + + + + + The GS_APP_KUDO_INSTALLS_USER_DOCS means we get the + blue "Documentation" award in the details page; there are many + kudos to award to deserving apps. + + + + + Setting the license means we don't get the non-free warning — + removing the 3rd party warning can be done using + GS_APP_QUIRK_PROVENANCE + + + + + The icon will be loaded into a pixbuf of the correct size when + needed by the UI. You must ensure that icons are available at + common sizes. For icons of type GsRemoteIcon, the + icons plugin will download and cache the icon + locally. + + + + + To show this fake application just compile and install the plugin, + touch ~/chiron and then restart gnome-software. + To avoid restarting gnome-software each time a + proper plugin would create a GFileMonitor object to + monitor files. + + + + + + + + + + By filling in the optional details (which can also be filled in using + refine_async() you can also make the details + page a much more exciting place. + Adding a set of screenshots is left as an exercise to the reader. + + + + + + + + +

+ +

+ Downloading Metadata and Updates + + + The plugin loader supports a refresh_metadata_async() vfunc that + is called in various situations. + To ensure plugins have the minimum required metadata on disk it is + called at startup, but with a cache age of infinite. + This basically means the plugin must just ensure that + any data exists no matter what the age. + + + Usually once per hour, we'll call refresh_metadata_async() but + with the correct cache age set (typically a little over 24 hours) which + allows the plugin to download new metadata or payload files from remote + servers. + The gs_utils_get_file_age() utility helper can help you + work out the cache age of a file, or the plugin can handle it some other + way. + + + For the Flatpak plugin we just make sure the AppStream metadata exists + at startup, which allows us to show search results in the UI. + If the metadata did not exist (e.g. if the user had added a remote + using the command-line without gnome-software running) then we would + show a loading screen with a progress bar before showing the main UI. + On fast connections we should only show that for a couple of seconds, + but it's a good idea to try any avoid that if at all possible in the + plugin. + Once per day the gs_plugin_get_updates() method is called, + and then gs_plugin_download_app() may be called if the + user has configured automatic updates. + This is where the Flatpak plugin would download any ostree trees (but + not doing the deploy step) so that the applications can be updated live + in the details panel without having to wait for the download to complete. + In a similar way, the fwupd plugin downloads the tiny LVFS metadata with + refresh_metadata_async() and then downloads the large firmware + files themselves when gs_plugin_download() or + gs_plugin_download_app() is called. + + + Note, if the downloading fails it's okay to return FALSE; + the plugin loader continues to run all plugins and just logs an error + to the console. We'll be calling into refresh_metadata_async() + again in only another hour, so there's no need to bother the user. + For actions like gs_plugin_app_install we also do the same + thing, but we also save the error on the GsApp itself so that the UI is + free to handle that how it wants, for instance showing a GtkDialog + window for example. + + + Refresh example + +static void progress_cb (gsize bytes_downloaded, + gsize total_download_size, + gpointer user_data); +static void download_file_cb (GObject *source_object, + GAsyncResult *result, + gpointer user_data); + +static void +gs_plugin_example_refresh_metadata_async (GsPlugin *plugin, + guint64 cache_age_secs, + GsPluginRefreshMetadataFlags flags, + GCancellable *cancellable, + GError **error) +{ + const gchar *metadata_filename = "/var/cache/example/metadata.xml"; + const gchar *metadata_url = "https://www.example.com/new.xml"; + g_autoptr(GFile) file = g_file_new_for_path (metadata_filename); + g_autoptr(GTask) task = NULL; + g_autoptr(SoupSession) soup_session = NULL; + + task = g_task_new (plugin, cancellable, callback, user_data); + g_task_set_source_tag (task, gs_plugin_example_refresh_metadata_async); + + soup_session = gs_build_soup_session (); + + /* is the metadata missing or too old? */ + if (gs_utils_get_file_age (file) > cache_age_secs) { + gs_download_file_async (soup_session, + metadata_url, + file, + G_PRIORITY_LOW, + progress_cb, + plugin, + cancellable, + download_file_cb, + g_steal_pointer (&task)); + return; + } + + g_task_return_boolean (task, TRUE); +} + +static void +progress_cb (gsize bytes_downloaded, + gsize total_download_size, + gpointer user_data) +{ + g_debug ("Downloaded %zu of %zu bytes", bytes_downloaded, total_download_size); +} + +static void +download_file_cb (GObject *source_object, + GAsyncResult *result, + gpointer user_data) +{ + GsPlugin *plugin = GS_PLUGIN (source_object); + g_autoptr(GTask) task = g_steal_pointer (&user_data); + + if (!gs_download_file_finish (result, &local_error)) { + g_task_return_error (task, g_steal_pointer (&local_error)); + } else { + g_debug ("successfully downloaded new metadata"); + g_task_return_boolean (task, TRUE); + } +} + +static gboolean +gs_plugin_example_refresh_metadata_finish (GsPlugin *plugin, + GAsyncResult *result, + GError **error) +{ + return g_task_propagate_boolean (G_TASK (result), error); +} + + +

+ +

+ Adding Application Information Using Refine + + + As previous examples have shown it's very easy to add a new + application to the search results, updates list or installed list. + Some plugins don't want to add more applications, but want to modify + existing applications to add more information depending on what is + required by the UI code. + The reason we don't just add everything at once is that for + search-as-you-type to work effectively we need to return results in + less than about 50ms and querying some data can take a long time. + For example, it might take a few hundred ms to work out the download + size for an application when a plugin has to also look at what + dependencies are already installed. + We only need this information once the user has clicked the search + results and when the user is in the details panel, so we can save a + ton of time not working out properties that are not useful. + + + Refine example + +static void +gs_plugin_example_refine_async (GsPlugin *plugin, + GsAppList *list, + GsPluginRefineFlags flags, + GCancellable *cancellable, + GAsyncReadyCallback callback, + gpointer user_data) +{ + g_autoptr(GTask) task = NULL; + + task = g_task_new (plugin, cancellable, callback, user_data); + g_task_set_source_tag (task, gs_plugin_example_refine_async); + + /* not required */ + if ((flags & GS_PLUGIN_REFINE_FLAGS_REQUIRE_LICENSE) == 0) { + g_task_return_boolean (task, TRUE); + return; + } + + for (guint i = 0; i < gs_app_list_length (list); i++) { + GsApp *app = gs_app_list_index (list, i); + + /* already set */ + if (gs_app_get_license (app) != NULL) { + g_task_return_boolean (task, TRUE); + return; + } + + /* FIXME, not just hardcoded! */ + if (g_strcmp0 (gs_app_get_id (app, "chiron.desktop") == 0)) + gs_app_set_license (app, "GPL-2.0 and LGPL-2.0+"); + } + + g_task_return_boolean (task, TRUE); +} + +static gboolean +gs_plugin_example_refine_finish (GsPlugin *plugin, + GAsyncResult *result, + GError **error) +{ + return g_task_propagate_boolean (G_TASK (result), error); +} + + + + This is a simple example, but shows what a plugin needs to do. + It first checks if the action is required, in this case + GS_PLUGIN_REFINE_FLAGS_REQUIRE_LICENSE. + This request is more common than you might expect as even the search + results shows a non-free label if the license is unspecified or + non-free. + It then checks if the license is already set, returning with success + if so. + If not, it checks the application ID and hardcodes a license; in the + real world this would be querying a database or parsing an additional + config file. + As mentioned before, if the license value is freely available without + any extra work then it's best just to set this at the same time as + when adding the app with gs_app_list_add(). + Think of refine as adding things that cost time to + calculate only when really required. + + + The UI in gnome-software is quite forgiving for missing data, hiding + sections or labels as required. + Some things are required however, and forgetting to assign an icon or + short description will get the application vetoed so that it's not + displayed at all. + Helpfully, running gnome-software --verbose on the + command line will tell you why an application isn't shown along with + any extra data. + + +

+ +

+ Adopting AppStream Applications + + + There's a lot of flexibility in the gnome-software plugin structure; + a plugin can add custom applications and handle things like search and + icon loading in a totally custom way. + Most of the time you don't care about how search is implemented or how + icons are going to be loaded, and you can re-use a lot of the existing + code in the appstream plugin. + To do this you just save an AppStream-format XML file in either + /usr/share/swcatalog/xml/, + /var/cache/swcatalog/xml/ or + ~/.local/share/swcatalog/xml/. + GNOME Software will immediately notice any new files, or changes to + existing files as it has set up the various inotify watches. + + + This allows plugins to care a lot less about how applications are + going to be shown. + For example, the flatpak plugin downloads AppStream data + for configured remotes during refresh_metadata_async(). + + + The only extra step a plugin providing its own apps needs to do + is to implement the gs_plugin_adopt_app() function. + This is called when an application does not have a management plugin + set, and allows the plugin to claim the + application for itself so it can handle installation, removal and + updating. + + + Another good example is the fwupd that wants to handle + any firmware we've discovered in the AppStream XML. + This might be shipped by the vendor in a package using Satellite, + or downloaded from the LVFS. It wouldn't be kind to set a management + plugin explicitly in case XFCE or KDE want to handle this in a + different way. This adoption function in this case is trivial: + + + + +void +gs_plugin_adopt_app (GsPlugin *plugin, GsApp *app) +{ + if (gs_app_get_kind (app) == AS_COMPONENT_KIND_FIRMWARE) + gs_app_set_management_plugin (app, plugin); +} + + +

+ +

+ Using The Plugin Cache + + + GNOME Software used to provide a per-process plugin cache, + automatically de-duplicating applications and trying to be smarter + than the plugins themselves. + This involved merging applications created by different plugins and + really didn't work very well. + For versions 3.20 and later we moved to a per-plugin cache which + allows the plugin to control getting and adding applications to the + cache and invalidating it when it made sense. + This seems to work a lot better and is an order of magnitude less + complicated. + Plugins can trivially be ported to using the cache using something + like this: + + + + /* create new object */ + id = gs_plugin_flatpak_build_id (inst, xref); +- app = gs_app_new (id); ++ app = gs_plugin_cache_lookup (plugin, id); ++ if (app == NULL) { ++ app = gs_app_new (id); ++ gs_plugin_cache_add (plugin, id, app); ++ } + + + + Using the cache has two main benefits for plugins. + The first is that we avoid creating duplicate GsApp objects for the + same logical thing. + This means we can query the installed list, start installing an + application, then query it again before the install has finished. + The GsApp returned from the second list_apps() + request will be the same GObject, and thus all the signals connecting + up to the UI will still be correct. + This means we don't have to care about migrating + the UI widgets as the object changes and things like progress bars just + magically work. + + + The other benefit is more obvious. + If we know the application state from a previous request we don't have + to query a daemon or do another blocking library call to get it. + This does of course imply that the plugin is properly invalidating + the cache using gs_plugin_cache_invalidate() which it + should do whenever a change is detected. + Whether a plugin uses the cache for this reason is up to the plugin, + but if it does it is up to the plugin to make sure the cache doesn't + get out of sync. + +

+ +

Policy

+ GNOME Software can optionally use a ratings and reviews service offered by + your distribution. + If enabled, GNOME Software will notify a web service that a specific + application has been installed or removed. + This information about which software you use helps us provide other users + with more accurate recommendations and helps us to choose applications to + feature on the overview page. +

+ When submitting ratings your IP address is sent along with the usage information. + This is exactly the same information submitted viewing this web page. + A one-way hash of this address is also stored in a database to prevent + duplicate entries being added by the same user, but this can not be used to + identify specific users or network addresses. +

+ We will never share the list of applications or your IP address with third + parties other than the original distribution web-service used by GNOME Software. +

Policy

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