Nerves + LiveView Example

This example shows a Nerves Project with a Phoenix server embedded in the same application. In contrast to a poncho project, there is only one application supervision tree containing the Phoenix Endpoint and any processes running on the device.

Configuration

The order of configuration is loaded in a specific order:

• config.exs
• host.exs or target.exs based on MIX_TARGET
• prod.exs, dev.exs, or test.exs based on MIX_ENV
• runtime.exs at runtime

To make configuration slightly more straightforward, the application is run with MIX_ENV=prod when on the device. Therefore, the configuration for Phoenix on the target device is in the prod.exs config file.

Developing

You can start the application just like any Phoenix project:

iex -S mix phx.server

Flashing to a Device

You can burn the first image with the following commands:

# If you want to enable wifi:
# export NERVES_SSID="NetworkName" && export NERVES_PSK="password"
MIX_ENV=prod MIX_TARGET=host mix do deps.get, assets.deploy
MIX_ENV=prod MIX_TARGET=rpi3 mix do deps.get, firmware, burn

Once the image is running on the device, the following will build and update the firmware over ssh.

# If you want to enable wifi:
# export NERVES_SSID="NetworkName" && export NERVES_PSK="password"
MIX_ENV=prod MIX_TARGET=host mix do deps.get, assets.deploy
MIX_ENV=prod MIX_TARGET=rpi3 mix do deps.get, firmware, upload your_app_name.local

Network Configuration

The network and WiFi configuration are specified in the target.exs file. In order to specify the network name and password, they must be set as environment variables NERVES_SSID NERVES_PSK at runtime.

If they are not specified, a warning will be printed when building firmware, which either gives you a chance to stop the build and add the environment variables or a clue as to why you are no longer able to access the device over WiFi.

Making It Your Own

To use this project as a start for your own Nerves/LiveView project, first replace the following strings throughout the project:

• HelloLiveView -> YourAppName
• hello_live_view -> your_app_name

# Might be necessary in MacOS to avoid a sed "illegal byte sequence" error
# export LC_CTYPE=C
# export LANG=C

find . -type f \( -iname "*.ex*" ! -path "./deps/*" ! -path "./_build/*" \) -print0 | xargs -0 sed -i '' -e 's/HelloLiveView/YourAppName/g'
find . -type f \( -iname "*.ex*" ! -path "./deps/*" ! -path "./_build/*" \) -print0 | xargs -0 sed -i '' -e 's/hello_live_view/your_app_name/g'
sed -i '' 's/hello_live_view/your_app_name/g' ./scripts/deploy.sh

Then rename the files and directories in lib:

mv lib/hello_live_view lib/your_app_name
mv lib/hello_live_view_web lib/your_app_name_web
mv lib/hello_live_view.ex lib/your_app_name.ex
mv liv/hello_live_view_web.ex lib/your_app_name_web.ex