nerves_livebook

# Distributed Erlang

## Introduction

[Distributed Erlang](http://erlang.org/doc/reference_manual/distributed.html)
lets you join multiple Erlang instances (nodes) together to enable
near-transparent message passing in programs, debugging, and remote code
updates. This Livebook shows a couple ways of using it with the Nerves Livebook
image.

## Setup

First, you'll need to know the name of this node and the cookie.

```elixir
"My name is '#{node()}' and my cookie is '#{Node.get_cookie()}'."
```

Now try connecting to this node by running the following command in a shell on
your computer:

```elixir
"iex --cookie '#{Node.get_cookie()}' --name me@myhost.local --remsh #{node()}"
```

You should get an IEx prompt. Everything you type at that prompt will run on
the device and not your computer.  To verify this, try running the following:

```text
iex> use Toolshed
iex> uname
Nerves nerves-2e6d nerves_livebook 0.1.0 (9e61db44-bbfd-5430-ab73-daedf5ebce81) arm
```

Use CTRL-C to exit when you're done. If you run `:init.stop()`, you'll end up
rebooting the device (probably not what you want).

## Remote Livebook

You can run Livebook on your laptop and connect to the device! This is useful
if you want to save your code notebooks locally. To do this,

1. Follow the [Livebook usage
   instructions](https://github.com/nerves-livebook/nerves_livebook) and start Livebook running
   on your laptop.
2. Open or create a new Livebook
3. Go to **Settings -> Runtime** and select **Attached Node**
4. Paste in this node's name and **Connect**

## Observer

Observer is a graphical tool for exploring an Erlang runtime. Connect to this
device by first starting IEx on your laptop with the same cookie we're using
here. For example:

```elixir
"iex --cookie '#{Node.get_cookie()}' --name me@myhost.local"
```

Then at the IEx prompt, run `:observer.start()`. Go to the **Nodes** menu and
**Connect node**. Copy in this device's node name like we found above and the
UI should quickly update to reflect what's running here.