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Avena: Edge computing for the farm.

What is Avena?

Avena is the accumulation of the lessoned learned while developing the OATS Center ISOBlue project. Avena is a software foundation suitable for devices like ISOBlue, but with more flexible data collection, streaming, deployment, configuration, etc then ISOBlue originally had.

The operating system is based on Debian and includes modern tools, such as: Docker, Wireguard, GPS/Chrony timesync, SSH CA, etc. The core is delivered and maintained by Ansible, know as the oats.avena collection on Ansible Galaxy. In many cases, as long as you have a device that supports Debian (or similar), Avena should be installable.

Origin of "Avena"

The word "avena" means oats in Spanish. "Oats" stands for our center's name: Open Ag Technology and Systems Center.

What is in this repo

This repo contains all development files for Avena and ISOblue related projects, including but not limited to:

  • Avena Ansible scripts
  • Hardware expansions design for supported platforms
  • Case/enclosure designs for supported platforms
  • Software for ISOBlue
  • Documentation's

Where is ISOBlue?

Don't worry, ISOBlue is still here to stay! The newer versions of ISOBlue are powered by Avena, leveraging docker for most of functionality. With this setup, ISOBlue is still the CAN bus to cloud logger we all know and love, but with additional multi-user edge computing capabilities.

What is ISOBlue (for those that don't know)?

ISOBlue is an open-source project. Its main goal is to create a set of open-source agricultural telematic device that collects and streams ISO 11783 (ISOBUS) data from modern agricultural machines. The most recent iteration, ISOBlue 2.0, runs Linux on a single board computer that is equipped with a cell modem, a SSD, and a USB GPS module for network connectivity, storage, and positioning purposes.

Using Avena to manage your fleet

The latest release of the Avena collections can be downloaded using the ansible-galaxy command. But first, you must create an Ansible project for your fleet and define the inventory. This guide will walk you through our recommend setup.

Much of this is based on Jeff Geerling's excellent "Ansible best practices: using project-local collections and roles" article. We think you should read it.

TODO: Make an open-source version of oats-fleet as an example.

Create a project folder

We recommend that you create a folder of ansible configurations, galaxy collections, roles, and playbooks for your fleet. Ansible has several folder structures that they support, our favorite is something like:

.
├── ansible.cfg
├── ansible_collections
│   └── oats
│       └── avena
├── inventory
│   ├── group_vars
│   │   └── fleet.yml
│   ├── hosts
│   └── host_vars
│       ├── device-1.yml
│       ├── device-2.yml
│       └── device-3.yml
├── isoblue.yml
├── isoblue-hd.yml
├── roles
│   └── custom-tests
│       ├── files
│       ├── templates
│       ├── defaults
│       └── custom-tests.yml
└── requirements.yml

Where:

  • isoblue.yml and isoblue-hd.yml are examples of playbooks that depend on Avena collection roles, but also contain custom tasks for each specific device type in your fleet.
  • device-1.yml, device-2.yml, and device-3.yml are example host variable files for the hostnames (defined in hosts) device-1, device-2, and device-3, respectfully.
  • fleet.yml are group variables for the hosts within the fleet group as defined in the hosts file.

This folder may also contain any standard Ansible file, e.g., roles and used within playbooks like any Ansible project.

For more details, check out Ansible's content organization documentation.

Create an ansible.cfg

We recommend Jeff Geerling's minimal default (source).

This configuration forces galaxy installed collections and roles to live within the project, rather then your home directory. This improves repeatable builds/runs. We also strongly recommend that you consider committing ansible_collections to version control (as Jeff also suggests), at least until ansible-galaxy has a true version locking scheme.

[defaults]

nocows = True
collections_paths = ./
roles_path = ./roles

Creating a requirements.yml

requirements.yml defines what Ansible Galaxy dependencies are needed for the project. For a basic Avena deployment, only the oats.avena collection is needed. If you don't know what version you need, then you should probably use whatever is newest.

---
collections:
  - name: oats.avena
    version: 0.1.0

Installing ansible requirements

From Galaxy (typical)

$ ansible-galaxy install -r requirements.yml

From a build

$ ansible-galaxy collection install oats-avena-0.1.0.tar.gz

From git

Note: This method ignores requirements.yml for the Avena collection. Be sure to properly release your changes and update requirements.yml when your done.

I find it easiest to clone this repo locally and link it into your projects ansible_collections folder. Something like

$ ln -rs ../isoblue-avena/ansible/avena ./ansible_collections/oats/`

when at the root of your project and isoblue-avena is cloned into the path ../isoblue-avena relative your project.

Create a fleet playbook

If you don't already have one, create a playbook for your fleet. Here you can add any type of custom tasks and roles as you would like. To deploy Avena, you must include at least the oats.avena.core role.

For example, the below playbook would deploy the Avena core along with GPS time synchronization, enable a cell modem, use CA based SSH authentication, and a wireguard VPN.

- hosts: fleet
  roles:
    - oats.avena.core
    - oats.avena.gps_time
    - oats.avena.cell
    - oats.avena.ca
    - oats.avena.wireguard

Vault (if using avena-ca)

Connecting to Vault

Note: There are other ways to connect / authenticate with vault. This is an example of userpass.

$ export VAULT_ADDR="http://172.16.0.1:8200"
$ vault login -method=userpass username=avena
Password (will be hidden): <enter-password>

Obtaining a certificate

A certificate is only need after the initial deploy. A plain password is used to authenticate until the avena-ca role completes. However, if the deploy fails, you may also need one to restart the process.

$ vault write -field=signed_key avena-client-signer/sign/admin public_key=@$HOME/.ssh/id_ed25519.pub > ~/.ssh/id_ed25519-cert.pub

Where a Vault CA signer is mounted at avena-client-signer with sufficient permissions for the admin role and an ed25519 SSH user key.

Deploying a new node

  1. Install Debian using your hardware platform's installation guide.

  2. Add the node to your fleet's inventory and configure variables as needed.

  3. Update your systems Vault CA certificate (if needed) using the Vault section above.

  4. Complete the initial deploy by running the following from within your project folder:

    ANSIBLE_HOST_KEY_CHECKING=False ansible-playbook isoblue.yml -i inventory --limit device-1 -e "ansible_ssh_host=10.0.0.2" -k

    Where,

    • ANSIBLE_HOST_KEY_CHECKING=False: Optional. Disable host key checking because it is unlikely that you have already manually approved the installation's default host key. The default key will be replaced by an ed25519 key. You will need to locally trust that key before any future Ansible commands.

      • Note: If using avena-ca, then all you need to trust on your local computer is the CA key. After that, all fleet nodes are trusted.

    • -e - "ansible_ssh_host=<host-ip>": Optional. Temporarily overrides the host address. Ansible variables will still be set by the hostfile defination, but Ansible will SSH into the provided IP address. This is useful:

      • The node deployed is being deployed on a local network, but the final public IP is already known.
      • The node will use a Wireguard (or similar) VPN and the hostfile reflects the VPN address.

    • -k: Optional. Enter the SSH password at runtime. This is useful when using avena-ca (or some other password less based authentication). The initial deploy is authenticated by password, but all following Ansible commands are password less.

      • If passwords will always be used, then you could securely store each node's password in the inventory with Ansible vault (not to be confused with Hashicorp Vault from above).

Updating nodes

  1. Update your systems Vault CA certificate (if needed) using the Vault section above.
  2. Run the playbook of intrest
   $ ansible-playbook isoblue.yml -i inventory/

Note: You can include the --limit flag if you want to work on some nodes