= meta-updater

This layer enables over-the-air updates (OTA) with https://github.com/ostreedev/ostree[OSTree] and https://github.com/advancedtelematic/aktualizr[Aktualizr].

https://github.com/ostreedev/ostree[OSTree] is a tool for atomic full file system upgrades with rollback capability. OSTree has several advantages over traditional dual-bank systems, but the most important one is that it minimizes network bandwidth and data storage footprint by sharing files with the same contents across file system deployments.

https://github.com/advancedtelematic/aktualizr[Aktualizr] (and https://github.com/advancedtelematic/rvi_sota_client[RVI SOTA client]) add authentication and provisioning capabilities to OTA and are integrated with OSTree. You can connect with the open-source https://github.com/advancedtelematic/rvi_sota_server[RVI SOTA server] or sign up for a free account at https://app.atsgarage.com[ATS Garage] to get started.

== Build

=== Quickstart

If you don't already have a Yocto project that you want to add OTA to, you can use the https://docs.atsgarage.com/quickstarts/raspberry-pi.html[ATS Garage Quickstart] project to rapidly get up and running on a Raspberry Pi. It takes a standard https://www.yoctoproject.org/tools-resources/projects/poky[poky] distribution, and adds OTA and OSTree capabilities.

=== Adding meta-updater capabilities to your build

If you already have a Yocto-based project and you want to add atomic filesystem updates to it, you just need to do three things:

1.  Clone the `meta-updater` layer and add it to your https://www.yoctoproject.org/docs/2.1/ref-manual/ref-manual.html#structure-build-conf-bblayers.conf[bblayers.conf].
2.  Clone BSP integration layer (`meta-updater-$\{PLATFORM}`, e.g. https://github.com/advancedtelematic/meta-updater-raspberrypi[meta-updater-raspberrypi]) and add it to your `conf/bblayers.conf`. If your board isn't supported yet, you could write a BSP integration for it yourself. See the <<Adding support for your board>> section for the details.
3.  Set up your https://www.yoctoproject.org/docs/2.1/ref-manual/ref-manual.html#var-DISTRO[distro]. If you are using "poky", the default distro in Yocto, you can change it in your `conf/local.conf` to "poky-sota". Alternatively, if you are using your own or third party distro configuration, you can add `INHERIT += " sota"` to it, thus combining capabilities of your distro with meta-updater features.

You can then build your image as usual, with bitbake. After building the root file system, bitbake will then create an https://ostree.readthedocs.io/en/latest/manual/adapting-existing/[OSTree-enabled version] of it, commit it to your local OSTree repo and (optionally) push it to a remote server. Additionally, a live disk image will be created (normally named `$\{IMAGE_NAME}.-sdimg-ota` e.g. `core-image-raspberrypi3.rpi-sdimg-ota`). You can control this behaviour through <<variables in your local.conf,OSTree-related variables in your local.conf>>.

=== Build in AGL

With AGL you can just add agl-sota feature while configuring your build environment:

....
source meta-agl/scripts/aglsetup.sh -m porter agl-demo agl-appfw-smack agl-devel agl-sota
....

You can then run:

....
bitbake agl-demo-platform
....

and get as a result an `ostree_repo` folder in your images directory (`tmp/deploy/images/$\{MACHINE}/ostree_repo`). It will contain:

* your OSTree repository, with the rootfs committed as an OSTree deployment,
* an `otaimg` bootstrap image, which is an OSTree physical sysroot as a burnable filesystem image, and optionally
* some machine-dependent live images (e.g. `.rpi-sdimg-ota` for Raspberry Pi or `.porter-sdimg-ota` Renesas Porter board).

Although `aglsetup.sh` hooks provide reasonable defaults for SOTA-related variables, you may want to tune some of them.

=== Build problems

Multilib systems may require adding this line to `local.conf`:

....
HOSTTOOLS += "x86_64-linux-gnu-gcc"
....

Ubuntu users that encounter an error due to missing `Python.h` should install `libpython2.7-dev` on their host machine.

== Supported boards

Currently supported platforms are

* https://github.com/advancedtelematic/meta-updater-raspberrypi[Raspberry Pi3]
* https://github.com/advancedtelematic/meta-updater-minnowboard[Minnowboard]
* https://github.com/advancedtelematic/meta-updater-qemux86-64[Native QEMU emulation]

=== Adding support for your board

If your board isn't supported yet, you can add board integration code yourself. The main purpose of this code is to provide a bootloader that will be able to use https://ostree.readthedocs.io/en/latest/manual/atomic-upgrades/[OSTree's boot directory]. In the meta-updater integration layers we have written so far, the basic steps are:

1.  Make the board boot into http://www.denx.de/wiki/U-Boot[U-Boot]
2.  Make U-boot import variables from /boot/loader/uEnv.txt and load the kernel with initramfs and kernel command line arguments according to what is set in this file.

You may take a look into https://github.com/advancedtelematic/meta-updater-minnowboard[Minnowboard] or https://github.com/advancedtelematic/meta-updater-raspberrypi[Raspberry Pi] integration layers for examples.

Although we have used U-Boot so far, other boot loaders can be configured work with OSTree as well.

== SOTA-related variables in `local.conf`

* `OSTREE_REPO` - path to your OSTree repository. Defaults to `$\{DEPLOY_DIR_IMAGE}/ostree_repo`
* `OSTREE_OSNAME` - OS deployment name on your target device. For more information about deployments and osnames see the https://ostree.readthedocs.io/en/latest/manual/deployment/[OSTree documentation]. Defaults to "poky".
* `OSTREE_INITRAMFS_IMAGE` - initramfs/initrd image that is used as a proxy while booting into OSTree deployment. Do not change this setting unless you are sure that your initramfs can serve as such a proxy.
* `SOTA_PACKED_CREDENTIALS` - when set, your ostree commit will be pushed to a remote repo as a bitbake step. This should be the path to a zipped credentials file in https://github.com/advancedtelematic/aktualizr/blob/master/docs/credentials.adoc[the format accepted by garage-push].
* `SOTA_CLIENT_PROV` - which provisioning method to use. Valid options are https://github.com/advancedtelematic/aktualizr/blob/master/docs/automatic-provisioning.adoc[`aktualizr-auto-prov`], https://github.com/advancedtelematic/aktualizr/blob/master/docs/implicit-provisioning.adoc[`aktualizr-implicit-prov`], and `aktualizr-hsm-prov`. The default is `aktualizr-auto-prov`. This can also be set to an empty string to avoid using a provisioning recipe.
* `SOTA_CLIENT_FEATURES` - extensions to aktualizr. Multiple can be specified if separated by spaces. Valid options are `hsm` (to build with HSM support) and `secondary-example` (to install an example https://github.com/advancedtelematic/aktualizr/blob/master/docs/legacysecondary.adoc[legacy secondary interface] in the image).
* `SOTA_LEGACY_SECONDARY_INTERFACE` - path to a legacy secondary interface installed on the device. To use the example interface from the Aktualizr repo, use `/usr/bin/example-interface` and make sure `SOTA_CLIENT_FEATURES = "secondary-example"`.
* `SOTA_SECONDARY_ECUS` - a list of paths separated by spaces of JSON configuration files for virtual secondaries on the host. These will be installed into `/var/sota/ecus` on the device.
* `SOTA_VIRTUAL_SECONDARIES` - a list of paths separated by spaces of JSON configuration files for virtual secondaries installed on the device. If `SOTA_SECONDARY_ECUS` is used to install them, then you can expect them to be installed in `/var/sota/ecus`.

== Usage

=== OSTree

OSTree used to include a simple HTTP server as part of the ostree binary, but this has been removed in more recent versions. However, OSTree repositories are self-contained directories, and can be trivially served over the network using any HTTP server. For example, you could use Python's SimpleHTTPServer:

....
cd tmp/deploy/images/qemux86-64/ostree_repo
python -m SimpleHTTPServer <port> # port defaults to 8000
....

You can then run ostree from inside your device by adding your repo:

....
# This behaves like adding a Git remote; you can name it anything
ostree remote add --no-gpg-verify my-remote http://<your-ip>:<port>

# If OSTREE_BRANCHNAME is set in local.conf, that will be the name of the
# branch. If not set, it defaults to the value of MACHINE (e.g. qemux86-64).
ostree pull my-remote <branch>

# poky is the OS name as set in OSTREE_OSNAME
ostree admin deploy --os=poky my-remote:<branch>
....

After restarting, you will boot into the newly deployed OS image.

For example, on the raspberry pi you can try this sequence:

....
# add remote
ostree remote add --no-gpg-verify agl-snapshot https://download.automotivelinux.org/AGL/snapshots/master/latest/raspberrypi3/deploy/images/raspberrypi3/ostree_repo/ agl-ota

# pull
ostree pull agl-snapshot agl-ota

# deploy
ostree admin deploy --os=agl agl-snapshot:agl-ota
....

=== garage-push

The https://github.com/advancedtelematic/aktualizr[aktualizr repo] contains a tool, garage-push, which lets you push the changes in OSTree repository generated by bitbake process. It communicates with an http server capable of querying files with HEAD requests and uploading them with POST requests. In particular, this can be used with http://www.atsgarage.com/[ATS Garage]. garage-push is used as follows:

....
garage-push --repo=/path/to/ostree-repo --ref=mybranch --credentials=/path/to/credentials.zip
....

You can set `SOTA_PACKED_CREDENTIALS` in your `local.conf` to automatically synchronize your build results with a remote server. Credentials are stored in an archive as described in the https://github.com/advancedtelematic/aktualizr/blob/master/docs/credentials.adoc[aktualizr documentation].

== QA with `oe-selftest`

This layer relies on the test framework oe-selftest for quality assurance. Follow the steps below to run the tests:

1. Append the line below to `conf/local.conf` to disable the warning about supported operating systems:
+
```
SANITY_TESTED_DISTROS = ""
```

2. If your image does not already include an ssh daemon such as dropbear or openssh, add this line to `conf/local.conf` as well:
+
```
IMAGE_INSTALL_append = " dropbear "
```

3. To be able to build an image for the grub tests, you will need to install https://github.com/tianocore/tianocore.github.io/wiki/OVMF[TianoCore's ovmf] package on your host system. On Debian-like systems, you can do so with this command:
+
```
sudo apt install ovmf
```

4. Run oe-selftest:
+
```
oe-selftest --run-tests updater
```

For more information about oe-selftest, including details about how to run individual test modules or classes, please refer to the https://wiki.yoctoproject.org/wiki/Oe-selftest[Yocto Project wiki].
