For using RAUC in your embedded project, you will need to build at least two versions of it:
- One for your host (build or development) system. This will allow you to create, inspect and modify bundles.
- One for your target system. This can act both as the service for handling the installation on your system, or as a command line tool that allows triggering the installation, inspecting your system and obtaining bundle information.
All common embedded Linux build system recipes for RAUC will solve the task of creating appropriate binaries for you as well as caring for bundle creation and partly system configuration. If you intend to use RAUC with Yocto, use the meta-rauc layer, in case you use PTXdist, simply enable RAUC in your configuration.
Note
When using the RAUC service from your application, the D-Bus interface is preferable to using the provided command-line tool.
To create an update bundle on your build host, RAUC provides the bundle
sub-command:
$ rauc bundle --cert=<certfile|certurl> --key=<keyfile|keyurl> <input-dir> <bundle-name>The <input-dir> must point to a directory containing all images, scripts
and other files that should be part of the created update bundle.
Additionally, a :ref:`RAUC manifest <sec_ref_manifest>` file manifest.raucm
is expected in <input-dir>.
The manifest describes the bundle content and the purpose of each included
image.
The created bundle will be stored under the given <bundle-name>.
The --cert and --key argument specify the certificate and private key
for signing the bundle.
They can be provided either as PEM files or as :ref:`PKCS#11-URIs
<pkcs11-support>` (to avoid storing sensitive key material as plain files).
With the optional --signing-keyring=<certfile> argument, the signed bundle
can be verified against the keyring file as part of the bundle creation
process, for example to prevent signing with invalid or expired certificates.
Note
A more detailed description of how to create bundles can be found in the :ref:`sec-integration-bundle` section in the :ref:`sec-integration` chapter.
$ rauc info --keyring=<certfile> [--output-format=<format>] <input-file>The info command lists the basic meta data of a bundle (compatible, version,
build-id, description) and the images and hooks contained in the bundle.
To authenticate the bundle information, it needs to be verified against a
keyring.
You can provide it via the system configuration or the --keyring
argument.
If the verification should explicitly be skipped, you may also use
--no-verify instead.
You can control the output <format> depending on your needs.
By default (or with readable), it will print a human readable representation of the
bundle not intended for being processed programmatically.
Alternatively, with shell you can obtain a shell-parsable description or a JSON
representation of the bundle content with json-2.
To actually install an update bundle on your target hardware, RAUC provides the
install command:
# rauc install <bundle>The <bundle> argument can be a local path, a local file URI, or a remote
(HTTP/HTTPS) URL.
Alternatively you can trigger a bundle installation using the D-Bus API.
Note
Installing a bundle requires RAUC to be integrated in your system. Refer to the :ref:`sec-integration` chapter for more.
For debugging purposes and for scripting it is helpful to gain an overview of
the current system as RAUC sees it.
The status command allows this:
# rauc status [--detailed] [--output-format=<format>]You can choose the output <format> depending on your needs.
By default (or with readable), it will print a human readable representation
of your system's most important properties.
Alternatively, with shell you can obtain a shell-parsable description,
or with json or json-pretty a JSON representation of the system status.
If more information is needed such as the slots' :ref:`status <slot-status>` add
the command line option --detailed.
Especially for use by other programs and services, RAUC creates symbolic links
in /run/rauc during service startup.
For example, on a system with A/B rootfs slots and corresponding appfs slots,
/run/rauc/slots/active/appfs would point to the appfs slot that corresponds
to the booted rootfs.
This could be used to mount the correct appfs without replicating the status
determination already implemented in RAUC.
For each artifact repository, a link at /run/rauc/artifacts/<repository-name>
points to the correct directory.
That way, installed artifacts can be found by following
/run/rauc/artifacts/<repository-name>/<artifact-name>.
Normally, the full system update chain is not complete before being sure that the newly installed system runs without any errors. As the definition and detection of a successful operation is really system-dependent, RAUC provides commands to preserve a slot as being the preferred one to boot or to discard a slot from being bootable.
# rauc status mark-goodAfter verifying that the currently booted system is fully operational, one wants to signal this information to the underlying bootloader implementation which then, for example, resets a boot attempt counter.
# rauc status mark-badIf the current boot failed in some kind, this command can be used to communicate that to the underlying bootloader implementation. In most cases this will disable the currently booted slot or at least switch to a different one.
Although not very useful in the field, both commands recognize an optional argument to explicitly identify the slot to act on:
# rauc status mark-{good,bad} [booted | other | <SLOT_NAME>]This is to maintain consistency with respect to rauc status mark-active
where that argument is definitively wanted, see :ref:`here
<optional-slot-identifier-argument>`.
One can think of a variety of reasons to switch the preferred slot for the next boot by hand, for example:
- Recurrently test the installation of a bundle in development starting from a known state.
- Activate a slot that has been installed sometime before and whose activation has explicitly been prevented at that time using the system configuration file's parameter :ref:`activate-installed <activate-installed>`.
- Switch back to the previous slot because one really knows better™.
To do so, RAUC offers the subcommand
# rauc status mark-active [booted | other | <SLOT_NAME>]where the optional argument decides which slot to (re-)activate at the expense
of the remaining slots. Choosing other switches to the next bootable slot
that is not the one that is currently booted. In a two-slot-setup this is
just... the other one. If one wants to explicitly address a known slot, one can
do so by using its slot name which has the form <slot-class>.<idx> (e.g.
rootfs.1), see :ref:`this <slot.slot-class.idx-section>` part of section
:ref:`System Configuration File <sec_ref_slot_config>`. Last but not least,
after switching to a different slot by mistake, before having rebooted this can
be remedied by choosing booted as the argument which is, by the way, the
default if the optional argument has been omitted.
The date and time of activation as well as the number of activations is part of
the slot's metadata which is stored in the slot status file, see section
:ref:`slot-status`.
RAUC provides several ways to customize the update process. Some allow adding and extending details more fine-grainedly, some allow replacing major parts of the default behavior of RAUC.
In general, there exist three major types of customization:
- configuration parameters (in the rootfs'
rauc/system.conffile) - handlers (executables in rootfs)
- hooks (executables in bundle)
The first type, configuration parameters, allow controlling parameters of the update in a predefined way.
The second type, using handlers, allows extending or replacing the installation process. They are executables (most likely shell scripts) located in the root filesystem and configured in the system's configuration file. They control static behavior of the system that should remain the same over future updates.
The last type are hooks. They are similar to handlers, except that they are contained in the update bundle. Thus they allow to flexibly extend or customize one or more updates by some special behavior. A common example would be using a per-slot post-install hook that handles configuration migration for a new software version. Hooks are especially useful to handle details of installing an update which were not considered in the previously deployed version.
In the following, configuration parameters, handlers and hooks will be explained in more detail.
Beside providing the basic slot layout, RAUC's system configuration file
(system.conf) also allows you to configure parts of its runtime behavior,
such as handlers (see below), paths, etc.
For a detailed list of possible configuration options,
see :ref:`sec_ref_slot_config` section in the :ref:`sec_ref` chapter.
Handlers are executables located in the target's root file system that allow extending the installation process on system side. They must be specified in the targets :ref:`sec_ref_slot_config`.
For a detailed list of all environment variables exported for the handler scripts, see the :ref:`sec-handler-interface` section.
Pre-Install Handler
[handlers]
pre-install=/usr/lib/rauc/pre-installRAUC will call the pre-install handler (if given) during the bundle installation process, right before calling the default or custom installation process. At this stage, the bundle is mounted, its content is accessible and the target group has been determined successfully.
If calling the handler fails or the handler returns a non-zero exit code, RAUC will abort installation with an error.
Post-Install Handler
[handlers]
post-install=/usr/lib/rauc/post-installThe post-install handler will be called right after RAUC successfully performed a system update. If any error occurred during installation, the post-install handler will not be called.
Note that a failed call of the post-install handler or a non-zero exit code will cause a notification about the error but will not change the result of the performed update anymore.
A possible usage for the post-install handler could be to trigger an automatic restart of the system.
System-Info Handler
[handlers]
system-info=/usr/lib/rauc/system-infoThe system-info handler is called after loading the configuration file. This way it can collect additional variables from the system, like the system's serial number.
The handler script can return variables by echoing <VARIABLE-NAME>=<value>
to stdout, like RAUC_SYSTEM_SERIAL or RAUC_SYSTEM_VARIANT.
Unlike handlers, hooks are defined in the update bundle and must be specified in the bundle's :ref:`sec_ref_manifest` file. All hooks are handled by a common executable that must be included in the bundle. Hooks allow the author of a bundle to add or replace functionality for the installation of a specific bundle. This can be useful for performing additional migration steps, checking for specific previously installed bundle versions or for manually handling updates of images RAUC cannot handle natively.
To reduce the complexity and number of files in a bundle, all hooks must be handled by a single executable that is registered in the bundle's manifest:
[hooks]
filename=hookThe filename must match the name of the script or binary executable placed
inside the content folder the bundle is generated from.
The actual hook invocations must be registered in the respective [image.*]
or [hooks] manifest sections via hooks=<hook-names> settings where
<hook-names> is a ;-separated list of hooks to invoke.
For each invoked hook, the common hook executable will be called with a specific argument indicating the name of the invoked hook. The executable is responsible for multiplexing the different hook calls.
In the following the available hooks are listed. Depending on their purpose, some are image-specific, i.e. they will be executed for the installation of a specific image only, while some other are global.
Install hooks operate globally on the bundle installation.
For a detailed list of all environment variables exported for the hooks executable, see the :ref:`sec-install-hook-interface` section.
For install hooks, the hook call argument is just the hook name itself (e.g.
install-check).
Install-Check Hook
[hooks]
filename=hook
hooks=install-checkThis hook will be executed instead of the normal compatible check in order to allow performing a custom compatibility check based on compatible and/or version information.
To indicate that a bundle should be rejected, the script must return with an exit code >= 10.
If available, RAUC will use the last line printed to standard error by the hook executable as the rejection reason message and provide it to the user:
#!/bin/sh
case "$1" in
install-check)
if [[ "$RAUC_MF_COMPATIBLE" != "$RAUC_SYSTEM_COMPATIBLE" ]]; then
echo "Compatible does not match!" 1>&2
exit 10
fi
;;
*)
exit 1
;;
esac
exit 0Slot hooks are called for each slot an image will be installed to. In order to
enable them, you have to specify them in the hooks key under the respective
image section.
Note that hook slot operations will be passed to the executable with the prefix
slot-. Thus if you intend to check for the pre-install hook, you have to
check for the argument to be slot-pre-install.
For a detailed list of all environment variables exported for the hooks executable, see the :ref:`sec-slot-hook-interface` section.
Pre-Install Hook
The pre-install hook will be called right before the update procedure for the respective slot will be started. For target slot types that represent a mountable file system, the hook will be executed with the target slots' file system mounted. Note that a broken or unformatted target slot will currently cause the installation to be aborted with an error.
[hooks]
filename=hook
[image.rootfs]
filename=rootfs.img
size=...
sha256=...
hooks=pre-installPost-Install Hook
The post-install hook will be called right after the update procedure for the respective slot was finished successfully. For slot types that represent a mountable file system, the hook will be executed with having the file system mounted. This allows to write some post-install information to the slot. It is also useful to copy files from the currently active system to the newly installed slot, for example to preserve application configuration data.
[hooks]
filename=hook
[image.rootfs]
filename=rootfs.img
size=...
sha256=...
hooks=post-installAn example on how to use a post-install hook:
#!/bin/sh
case "$1" in
slot-post-install)
# only rootfs needs to be handled
test "$RAUC_SLOT_CLASS" = "rootfs" || exit 0
touch "$RAUC_SLOT_MOUNT_POINT/extra-file"
;;
*)
exit 1
;;
esac
exit 0Install Hook
The install hook will replace the entire default installation process for the
target slot of the image it was specified for. Note that when having the install
hook enabled, pre- and post-install hooks will not be executed and having
an image (i.e. filename set) is optional, too!
The install hook allows to fully customize the way a slot is updated. This
allows performing special installation methods that are not natively supported
by RAUC, for example to upgrade the bootloader to a new version while also
migrating configuration settings.
[hooks]
filename=hook
[image.rootfs]
filename=rootfs.img
size=...
sha256=...
hooks=installor, without filename:
[hooks]
filename=hook
[image.datafs]
hooks=installFor some special tasks (recovery, testing, migration), it might be required to completely replace the default RAUC update mechanism and to only use its infrastructure and the signature verification for executing an application or a script on the target side.
For this case, RAUC allows to define a full custom handler in a bundle's manifest that will be executed instead of the built-in slot update handling:
[update]
compatible=Test Platform
[handler]
filename=custom-handler.shThe handler script/binary must be part of the bundle.
Refer manifest :ref:`[handler] <sec-manifest-handler>` section description for details about how the full custom handler can be configured and gets called.
The RAUC D-BUS API allows seamless integration into existing or project-specific applications, incorporation with bridge services such as the rauc-hawkbit client and also the rauc CLI uses it.
The API's service domain is de.pengutronix.rauc while the object path is
/.
The D-Bus API's main purpose is to trigger and monitor the installation
process via its Installer interface.
The InstallBundle method call triggers the installation of a given bundle in the
background and returns immediately.
Upon completion of the installation RAUC emits the Completed signal,
indicating either successful or failed installation.
For details on triggering the installation process, see the
:ref:`gdbus-method-de-pengutronix-rauc-Installer.InstallBundle` chapter in the
reference documentation.
While the installation is in progress, constant progress information will be
emitted in form of changes to the Progress property.
The progress property will be updated upon each change of the progress value. For details see the :ref:`gdbus-property-de-pengutronix-rauc-Installer.Progress` chapter in the reference documentation.
To monitor Progress property changes from your application, attach to the
PropertiesChanged signal and filter on the Operation properties.
Each progress step emitted is a tuple (percentage, message, nesting depth)
describing a tree of progress steps:
├"Installing" (0%) │ ├"Determining slot states" (0%) │ ├"Determining slot states done." (20%) │ ├"Checking bundle" (20%) │ │ ├"Verifying signature" (20%) │ │ └"Verifying signature done." (40%) │ ├"Checking bundle done." (40%) │ ... └"Installing done." (100%)
This hierarchical structure allows applications to decide for the appropriate
granularity to display information.
Progress messages with a nesting depth of 1 are only Installing and
Installing done..
A nesting depth of 2 means more fine-grained information while larger depths
are even more detailed.
Additionally, the nesting depth information allows the application to print
tree-like views as shown above.
The percentage value always goes from 0 to 100 while the message is
always a human-readable English string.
For internationalization you may use a
gettext-based approach.
Triggering an installation:
$ busctl call de.pengutronix.rauc / de.pengutronix.rauc.Installer InstallBundle sa{sv} "<bundle-path>/<bundle-url>" 0Mark a slot as good:
$ busctl call de.pengutronix.rauc / de.pengutronix.rauc.Installer Mark ss "good" "rootfs.0"Mark a slot as active:
$ busctl call de.pengutronix.rauc / de.pengutronix.rauc.Installer Mark ss "active" "rootfs.0"Get the Operation property containing the current operation:
$ busctl get-property de.pengutronix.rauc / de.pengutronix.rauc.Installer OperationGet the Progress property containing the progress information:
$ busctl get-property de.pengutronix.rauc / de.pengutronix.rauc.Installer ProgressGet the LastError property, which contains the last error that occurred during an installation.
$ busctl get-property de.pengutronix.rauc / de.pengutronix.rauc.Installer LastErrorGet the status of all slots
$ busctl call de.pengutronix.rauc / de.pengutronix.rauc.Installer GetSlotStatusGet the current primary slot
$ busctl call de.pengutronix.rauc / de.pengutronix.rauc.Installer GetPrimaryMonitor the D-Bus interface
$ busctl monitor de.pengutronix.raucObtain bundle information
$ busctl call de.pengutronix.rauc / de.pengutronix.rauc.Installer InspectBundle sa{sv} "<bundle-path>/<bundle-url>" 0When RAUC fails to start on your target during integration or later during installation of new bundles it can have a variety of causes.
This section will lead you through the most common options you have for debugging what actually went wrong.
In each case it is quite essential to know that RAUC, if not compiled with
-Dservice=false runs as a service on your target that is either
controlled by your custom application or by the RAUC command line interface.
The frontend will always only show the 'high level' error output, e.g. when an installation failed:
rauc-Message: 08:27:12.083: installing /home/enrico/Code/rauc/good-bundle-hook.raucb: LastError: Failed mounting bundle: failed to run mount: Child process exited with code 1
rauc-Message: 08:27:12.083: installing /home/enrico/Code/rauc/good-bundle-hook.raucb: idle
Installing `/home/enrico/Code/rauc/good-bundle-hook.raucb` failedIn simple cases this might be sufficient for identifying the actual problem, in more complicated cases this may give a rough hint. For a more detailed look on what went wrong you need to inspect the rauc service log instead.
If you run RAUC using systemd, the log can be obtained using
$ journalctl -u raucWhen using SysVInit, your service script needs to configure logging itself.
A common way is to dump the log, e.g. to /var/log/rauc.
It may also be worth starting the RAUC service via command line on a second
shell to have a live view of what is going on when you invoke e.g. rauc
install on the first shell.
Sometimes during development, it is useful to check whether the bundle contents
are as expected.
While RAUC bundles could just be mounted as a squashfs, using rauc mount
also uses the same checks and mechanisms as rauc install
(device-mapper/loopback & network support).
The bundle is mounted below the configured mount prefix (/mnt/rauc/bundle by
default).
When you are done, just use umount <mount point> to unmount the bundle.
$ rauc mount /var/tmp/test/good-verity-bundle.raucb
rauc-Message: 12:37:36.869: Reading bundle: /var/tmp/test/good-verity-bundle.raucb
rauc-Message: 12:37:36.889: Verifying bundle signature...
rauc-Message: 12:37:36.894: Verified inline signature by 'O = Test Org, CN = Test Org Release-1'
rauc-Message: 12:37:36.896: Mounting bundle '/var/tmp/test/good-verity-bundle.raucb' to '/mnt/rauc/bundle'
rauc-Message: 12:37:36.931: Configured loop device '/dev/loop0' for 24576 bytes
rauc-Message: 12:37:36.934: Configured dm-verity device '/dev/dm-0'
Mounted bundle at /mnt/rauc/bundle. Use 'umount /mnt/rauc/bundle' to unmount.
$ ls -l /mnt/rauc/bundle
total 21
-rw-r--r-- 1 root root 8192 Jun 21 14:51 appfs.img
-rwxr-xr-x 1 root root 2241 Sep 15 2017 custom_handler.sh
-rwxr-xr-x 1 root root 1421 Aug 31 2017 hook.sh
-rw-r--r-- 1 root root 308 Jun 21 14:51 manifest.raucm
-rw-r--r-- 1 root root 8192 Jun 21 14:51 rootfs.img
$ umount /mnt/rauc/bundleNote
This command is only intended for use during development.
Both for the service and the command line interface it is often useful to increase the log level for narrowing down the actual error cause or gaining more information about the circumstances when the error occurs.
RAUC uses glib and the glib logging framework with the basic log domain 'rauc'.
For simple cases, you can activate logging by passing the -d or --debug option to either the CLI:
# rauc install -d bundle.raucb ..or the service (you might need to modify your systemd or SysVInit service file).
# rauc service -dFor more fine grained and advanced debugging options, use the
G_MESSAGES_DEBUG environment variable.
This allows enabling different log domains. Currently available are:
| all: | enable all log domains |
|---|---|
| rauc: | enable default RAUC log domain (same as calling with |
| rauc-signature: | enable logging of signature details This will dump the full CMS structure during verification and can help identify problems with the signature details. |
| rauc-subprocess: | enable logging of subprocess calls This will dump the entire program call invoked by RAUC and can help tracing down or reproducing issues caused by other programs invoked. |
Example invocation:
# G_MESSAGES_DEBUG="rauc rauc-subprocess" rauc serviceIf you suspect an issue is related to network access (using the CURL library),
you can set RAUC_CURL_VERBOSE=1.
This will cause RAUC to enable CURLOPT_VERBOSE when configuring a CURL
context.
The RAUC source code repository provides a :ref:`qemu-test <sec-contributing-qemu-test>` script, mainly meant to be used for running the unit tests in a safe environment. It can also be used to reproduce issues and debug basic functionality of RAUC.
When running:
$ ./qemu-test systemyou will boot into a QEMU shell that has a mocked RAUC setup allowing you to inspect status, install procedure, etc. For example:
root@qemu-test:/home/user/git/rauc# rauc status
=== System Info ===
Compatible: Test Config
Variant:
Booted from: rootfs.0 (A)
=== Bootloader ===
Activated: rootfs.0 (A)
=== Slot States ===
x [rootfs.0] (/dev/root, raw, booted)
bootname: A
mounted: /
boot status: good
[appfs.0] (/dev/null, raw, active)
o [rootfs.1] (/tmp/rootdev, raw, inactive)
bootname: B
boot status: good
[appfs.1] (/tmp/appdev, raw, inactive)