chore(build): add multi-stage build with dev target

Introduces separate Docker stages for development workflow:
- base: minimal system setup (apt sources, sudo, make)
- dev: build dependencies installed, no project build
- runtime: full build (original behavior)

The dev target supports volume mounting for iterative development.

Signed-off-by: Laudin Molina Troconis <laudin.molinatroconis@silabs.com>

Author: lmolina

Dockerfile

@@ -1,12 +1,12 @@
 #!/bin/echo run with: docker build . -f
 # -*- coding: utf-8 -*-
 
-FROM arm32v7/debian:stretch
-ENV target_debian_arch armhf
+FROM arm32v7/debian:stretch AS base
+ENV target_debian_arch=armhf
 
-LABEL maintainer="Philippe Coval <philippe.coval@silabs.com>"
+LABEL maintainer="Laudin Molina Troconis <laudin.molinatroconis@silabs.com>"
 
-ENV DEBIAN_FRONTEND noninteractive
+ENV DEBIAN_FRONTEND=noninteractive
 
 RUN echo "# log: Setup system"  \
   && set -x \
@@ -16,17 +16,20 @@ RUN echo "# log: Setup system"  \
   && apt-get install -y sudo make \
   && date -u
 
-ENV project zipgateway
-ENV workdir /usr/local/src/${project}
+FROM base AS dev
+ENV project=zipgateway
+ENV workdir=/usr/local/src/${project}
 WORKDIR ${workdir}
 COPY helper.mk ${workdir}
-RUN echo "# log: Install ${project}" \
+RUN echo "# log: Setup dependencies for ${project}" \
   && set -x  \
   && ./helper.mk setup/debian/stretch \
+  && apt-get autoremove --purge \
+  && apt-get clean \
   && date -u
 
+FROM dev AS runtime
 COPY . ${workdir}
-WORKDIR ${workdir}
 RUN echo "# log: Build ${project}" \
   && set -x  \
   && ./helper.mk \

docker-compose.yml

@@ -1,10 +1,27 @@
 # -*- coding: utf-8 -*-
 
-version: "2"
-
 services:
-  default:
-    build: .
+  dev:
+    image: zipgateway-dev
+    build:
+      context: .
+      target: dev
+    volumes:
+      - .:/usr/local/src/zipgateway
+    working_dir: /usr/local/src/zipgateway
+    user: "${UID:-1000}:${GID:-1000}"
+    stdin_open: true
+    tty: true
+    command: bash
+
+  runtime:
+    build:
+      context: .
+      target: runtime
     command: tests
     devices:
       - /dev/ttyACM0:/dev/ttyACM0
+
+  # Alias for backward compatibility
+  default:
+    extends: runtime