Switch to Alpine for smaller image

Author: devatnull

backend/Dockerfile.sandbox

@@ -1,29 +1,20 @@
 # =============================================================================
-# Hardened Neovim + Tmux Sandbox Container
+# Hardened Neovim + Tmux Sandbox Container (Alpine - lightweight)
 # =============================================================================
-FROM ubuntu:24.04 AS base
-
-# Prevent interactive prompts
-ENV DEBIAN_FRONTEND=noninteractive
+FROM alpine:3.20
 
 # Install only what's needed
-RUN apt-get update && apt-get install -y --no-install-recommends \
+RUN apk add --no-cache \
     neovim \
     tmux \
     git \
     curl \
-    ca-certificates \
-    locales \
-    && rm -rf /var/lib/apt/lists/* \
-    && apt-get clean
-
-# Set locale
-RUN locale-gen en_US.UTF-8
-ENV LANG=en_US.UTF-8
-ENV LC_ALL=en_US.UTF-8
+    bash \
+    ncurses \
+    && rm -rf /var/cache/apk/*
 
 # Create non-root user
-RUN useradd -m -s /bin/bash -u 1000 learner
+RUN adduser -D -s /bin/bash -u 1000 learner
 
 # Setup practice directory with sample files
 RUN mkdir -p /home/learner/practice && \
@@ -41,6 +32,10 @@ COPY --chown=learner:learner containers/nvim-config/ /home/learner/.config/nvim/
 # Basic tmux config for learning
 COPY --chown=learner:learner containers/tmux.conf /home/learner/.tmux.conf
 
+# Set environment
+ENV TERM=xterm-256color
+ENV LANG=C.UTF-8
+
 # Set working directory
 WORKDIR /home/learner/practice