Add stages to dockerfile to speed up local dev builds

Dockerfile

@@ -3,7 +3,7 @@ ARG ELIXIR_VERSION=1.14
 ARG NODE_VERSION=20.2.0
 
 FROM node:${NODE_VERSION}-alpine AS node
-FROM elixir:${ELIXIR_VERSION}-alpine
+FROM elixir:${ELIXIR_VERSION}-alpine AS setup
 
 
 ### Install deps
@@ -47,6 +47,10 @@ EXPOSE 3000
 EXPOSE 4000
 ENV PORT=4000 UI_PORT=3000 MIX_ENV=dev
 
+# Create a new stage so that local dev setup can stop here
+# Local dev mounts into the container so there's no point in adding/compiling
+FROM setup AS compile
+
 ### Install dependencies and compile
 
 # Download and compile server deps

docker-compose.dev.yml

@@ -1,6 +1,11 @@
 version: "3"
 services:
  web:
+ build:
+ context: ./
+ target: setup
  command: sleep infinity
+ depends_on:
+ - db
  volumes:
  - .:/app