This guide will show you the most simple use case applicable to the Thistle Update Client: how to update a single file. You may run the update client directly on a desktop/laptop computer (Linux, macOS, or Windows) as it will run in the same manner on an embedded device.

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Tools needed

To get started you need to obtain:
  • The Thistle Update Client for your platform
  • The Thistle Release Helper to help packaging your updates
  • On the Thistle App. Visit the settings section of a project to obtain the API token (“Project Access Token”) to be used as THISTLE_TOKEN in the configuration step below.
Project's Access Token

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Configuration

# Set up your project's access token - Bash, on Linux/Unix or Windows Subsystem for Linux (WSL)
$ export THISTLE_TOKEN=$(cat)
(paste access token, press enter, then ctrl-d)

# Set up your project's access token - Windows PowerShell
$ $env:THISTLE_TOKEN = "[Access Token Obtained from Thistle App's Project Settings section]"

$ ./trh init -p="/tmp/persist"
First we initialize the local development environment by executing the init command. This will set the device trust model to Trust On First Use (TOFU) where devices are to be trusted upon joining the network. The init command requires the path to an on-device persistent directory. This path will be used by the client to store persistent data between restarts./tmp/persist was used in this example. The local signing key, device configuration file config.json and a release manfest template manifest.json will also be generated.
Your local working environment is now ready.

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What’s in an update

We will now package our first update. For the purpose of this test, the update will contain a single binary called my_app, that will be installed at path /tmp/my_app. Complete “rootfs” system update are also possible using similar commands. Updates are defined by manifest files, they contain the assets’ definition and a cryptographic signature. 
$ mkdir -p ./example
$ echo "hello world" > ./example/my_app

# my_app will be installed on target system at /tmp/my_app
$ ./trh prepare --target="./example" --file-base-path="/tmp"
Upon success, manifest.json will be amended for the OTA release.

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Upload and test deployed release

Now that we have prepared the update bundle, we can use the trh tool to upload the release and its assets. 
$ ./trh release
With the manifest fully uploaded to the Thistle Backend, alongside with its payload, it is now possible to fetch and install this update from any device running the Thistle Update Client, and the configuration we generated earlier on. 
./tuc -c ./config.json
# by default the TUC continues running. Use ctrl-C to exit from it.

# verify installation below
$ cat /tmp/my_app
hello world
You can confirm your file was installed as defined by looking at the install path /tmp/my_app.

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Upload a new update bundle

To update the manifest we just released with newer content, we need to re-run the prepare and release commands. All the devices using the configuration file config.json will then receive this update. 
echo "hello new world" > ./example/my_app
./trh prepare --target="./example" --file-base-path="/tmp"
./trh release

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Signing an update bundle with a key in KMS

If one does not want to manage a local signing key, a Thistle-managed, Cloud KMS-backed ECDSA-P256 key can be used to sign OTA update bundles. Add option --signing-method="remote" to all the above trh commands to use this remotely managed signing key. For example, 
trh --signing-method="remote" init ...
trh --signing-method="remote" prepare ...
trh --signing-method="remote" release

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More options

In this get started guide, we explained the usage of the Thistle Update Client alongside the Thistle Release Helper to perform updates on a single file - and many more use cases are supported!