k3s on Raspberry Pi: Phoenix Server

7 Feb 2020 11:17 k3s raspberry-pi docker elixir phoenix

Note: This is basically the same as the node.js server.

Creating the Phoenix app

It’s entirely possible to create the app inside the docker container, or on a completely different machine, but I’m going to do it locally, which means installing Erlang, Elixir and Phoenix first.

Then:

mix phx.new phoenix_server --no-ecto

If you answer ‘Y’ to the “Fetch and install dependencies?” prompt, this’ll take a while, but it’ll save doing it later in the docker build step.

`Dockerfile`

# Use an official Elixir runtime as a parent image
FROM elixir:latest

# Install hex, rebar and phoenix.
RUN mix local.hex --force \
    && mix local.rebar --force \
    && mix archive.install --force hex phx_new 1.4.12

# Install nvm
RUN curl -o- https://raw.githubusercontent.com/nvm-sh/nvm/v0.35.2/install.sh | bash

# Install node
ENV NODE_VERSION=v12.14.1
RUN set -e \
    && NVM_DIR="$HOME/.nvm" \
    && . "$NVM_DIR/nvm.sh" \
    && nvm install $NODE_VERSION

# Create app directory and copy the Elixir projects into it
RUN mkdir /app
COPY . /app
WORKDIR /app

# Compile the project
RUN mix do deps.get, compile

RUN set -e \
    && NVM_DIR="$HOME/.nvm" \
    && . "$NVM_DIR/nvm.sh" \
    && cd assets \
    && npm install \
    && node node_modules/webpack/bin/webpack.js --mode development

EXPOSE 4000

CMD ["/app/docker-entrypoint.sh"]

`docker-entrypoint.sh`

#!/bin/bash

set -e

export NVM_DIR="$HOME/.nvm"
. "$NVM_DIR/nvm.sh"

cd /app
exec mix phx.server

Make it executable:

chmod +x docker-entrypoint.sh

Note that the above runs the Phoenix app in development mode.

Create the docker image

Note that we switch to using a hyphen in the name at this point.

docker build -t phoenix-server .

Push it to the private docker repository

docker tag phoenix-server rpi201:5000/phoenix-server
docker push rpi201:5000/phoenix-server

Create a deployment

sudo kubectl create deployment phoenix-server --image=rpi201:5000/phoenix-server

Expose the deployment

sudo kubectl expose deployment phoenix-server --port 4000

Check it’s working

sudo kubectl get endpoints phoenix-server
curl 10.42.3.15:4000