run in Docker

.dockerignore

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+# This file excludes paths from the Docker build context.
+#
+# By default, Docker's build context includes all files (and folders) in the
+# current directory. Even if a file isn't copied into the container it is still sent to
+# the Docker daemon.
+#
+# There are multiple reasons to exclude files from the build context:
+#
+# 1. Prevent nested folders from being copied into the container (ex: exclude
+#    /assets/node_modules when copying /assets)
+# 2. Reduce the size of the build context and improve build time (ex. /build, /deps, /doc)
+# 3. Avoid sending files containing sensitive information
+#
+# More information on using .dockerignore is available here:
+# https://docs.docker.com/engine/reference/builder/#dockerignore-file
+
+.dockerignore
+
+# Ignore git, but keep git HEAD and refs to access current commit hash if needed:
+#
+# $ cat .git/HEAD | awk '{print ".git/"$2}' | xargs cat
+# d0b8727759e1e0e7aa3d41707d12376e373d5ecc
+.git
+!.git/HEAD
+!.git/refs
+
+# Common development/test artifacts
+/cover/
+/doc/
+/test/
+/tmp/
+.elixir_ls
+
+# Mix artifacts
+/_build/
+/deps/
+*.ez
+
+# Generated on crash by the VM
+erl_crash.dump
+
+# Static artifacts - These should be fetched and built inside the Docker image
+/assets/node_modules/
+/priv/static/assets/
+/priv/static/cache_manifest.json

Dockerfile

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+# Find eligible builder and runner images on Docker Hub. We use Ubuntu/Debian
+# instead of Alpine to avoid DNS resolution issues in production.
+#
+# https://hub.docker.com/r/hexpm/elixir/tags?page=1&name=ubuntu
+# https://hub.docker.com/_/ubuntu?tab=tags
+#
+# This file is based on these images:
+#
+#   - https://hub.docker.com/r/hexpm/elixir/tags - for the build image
+#   - https://hub.docker.com/_/debian?tab=tags&page=1&name=bullseye-20241223-slim - for the release image
+#   - https://pkgs.org/ - resource for finding needed packages
+#   - Ex: hexpm/elixir:1.18.0-erlang-27.2-debian-bullseye-20241223-slim
+#
+ARG ELIXIR_VERSION=1.18.0
+ARG OTP_VERSION=27.2
+ARG DEBIAN_VERSION=bullseye-20241223-slim
+
+ARG BUILDER_IMAGE="hexpm/elixir:${ELIXIR_VERSION}-erlang-${OTP_VERSION}-debian-${DEBIAN_VERSION}"
+ARG RUNNER_IMAGE="debian:${DEBIAN_VERSION}"
+
+FROM ${BUILDER_IMAGE} as builder
+
+# install build dependencies
+RUN apt-get update -y && apt-get install -y build-essential git \
+    && apt-get clean && rm -f /var/lib/apt/lists/*_*
+
+# prepare build dir
+WORKDIR /app
+
+# install hex + rebar
+RUN mix local.hex --force && \
+    mix local.rebar --force
+
+# set build ENV
+ENV MIX_ENV="prod"
+
+# install mix dependencies
+COPY mix.exs mix.lock ./
+RUN mix deps.get --only $MIX_ENV
+RUN mkdir config
+
+# copy compile-time config files before we compile dependencies
+# to ensure any relevant config change will trigger the dependencies
+# to be re-compiled.
+COPY config/config.exs config/${MIX_ENV}.exs config/
+RUN mix deps.compile
+
+COPY priv priv
+
+COPY lib lib
+
+COPY assets assets
+
+# # compile assets
+# RUN mix assets.deploy
+
+# Compile the release
+RUN mix compile
+
+# Changes to config/runtime.exs don't require recompiling the code
+COPY config/runtime.exs config/
+
+COPY rel rel
+RUN mix release
+
+# start a new build stage so that the final image will only contain
+# the compiled release and other runtime necessities
+FROM ${RUNNER_IMAGE}
+
+RUN apt-get update -y && \
+  apt-get install -y libstdc++6 openssl libncurses5 locales ca-certificates \
+  && apt-get clean && rm -f /var/lib/apt/lists/*_*
+
+# Set the locale
+RUN sed -i '/en_US.UTF-8/s/^# //g' /etc/locale.gen && locale-gen
+
+ENV LANG en_US.UTF-8
+ENV LANGUAGE en_US:en
+ENV LC_ALL en_US.UTF-8
+
+WORKDIR "/app"
+RUN chown nobody /app
+
+# set runner ENV
+ENV MIX_ENV="prod"
+
+# Only copy the final release from the build stage
+COPY --from=builder --chown=nobody:root /app/_build/${MIX_ENV}/rel/ws_server ./
+
+USER nobody
+
+# If using an environment that doesn't automatically reap zombie processes, it is
+# advised to add an init process such as tini via `apt-get install`
+# above and adding an entrypoint. See https://github.com/krallin/tini for details
+# ENTRYPOINT ["/tini", "--"]
+
+CMD ["/app/bin/server"]

assets/js/user_socket.js

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+// NOTE: The contents of this file will only be executed if
+// you uncomment its entry in "assets/js/app.js".
+
+// Bring in Phoenix channels client library:
+import {Socket} from "phoenix"
+
+// And connect to the path in "lib/ws_server_web/endpoint.ex". We pass the
+// token for authentication. Read below how it should be used.
+let socket = new Socket("/socket", {params: {token: window.userToken}})
+
+// When you connect, you'll often need to authenticate the client.
+// For example, imagine you have an authentication plug, `MyAuth`,
+// which authenticates the session and assigns a `:current_user`.
+// If the current user exists you can assign the user's token in
+// the connection for use in the layout.
+//
+// In your "lib/ws_server_web/router.ex":
+//
+//     pipeline :browser do
+//       ...
+//       plug MyAuth
+//       plug :put_user_token
+//     end
+//
+//     defp put_user_token(conn, _) do
+//       if current_user = conn.assigns[:current_user] do
+//         token = Phoenix.Token.sign(conn, "user socket", current_user.id)
+//         assign(conn, :user_token, token)
+//       else
+//         conn
+//       end
+//     end
+//
+// Now you need to pass this token to JavaScript. You can do so
+// inside a script tag in "lib/ws_server_web/templates/layout/app.html.heex":
+//
+//     <script>window.userToken = "<%= assigns[:user_token] %>";</script>
+//
+// You will need to verify the user token in the "connect/3" function
+// in "lib/ws_server_web/channels/user_socket.ex":
+//
+//     def connect(%{"token" => token}, socket, _connect_info) do
+//       # max_age: 1209600 is equivalent to two weeks in seconds
+//       case Phoenix.Token.verify(socket, "user socket", token, max_age: 1_209_600) do
+//         {:ok, user_id} ->
+//           {:ok, assign(socket, :user, user_id)}
+//
+//         {:error, reason} ->
+//           :error
+//       end
+//     end
+//
+// Finally, connect to the socket:
+socket.connect()
+
+// Now that you are connected, you can join channels with a topic.
+// Let's assume you have a channel with a topic named `room` and the
+// subtopic is its id - in this case 42:
+let channel = socket.channel("room:42", {})
+channel.join()
+  .receive("ok", resp => { console.log("Joined successfully", resp) })
+  .receive("error", resp => { console.log("Unable to join", resp) })
+
+export default socket

rel/overlays/bin/server

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+#!/bin/sh
+set -eu
+
+cd -P -- "$(dirname -- "$0")"
+PHX_SERVER=true exec ./ws_server start

rel/overlays/bin/server.bat

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+set PHX_SERVER=true
+call "%~dp0\ws_server" start