security: pin base images to python:3.12.13, remove apt/apk upgrade

Per Docker best practices, security patching should come from rebuilding
with updated base image tags, not from apt-get upgrade inside the
Dockerfile. Pinning to a specific patch version ensures reproducible
builds. Bump the version and rebuild to pick up new patches.

Author: tjbck

Dockerfile

@@ -1,4 +1,6 @@
-FROM python:3.12
+# Pin to a specific patch version for reproducible builds.
+# To pick up security patches, bump this version and rebuild.
+FROM python:3.12.13
 
 RUN apt-get update && apt-get install -y --no-install-recommends \
     # Core utilities
@@ -37,8 +39,6 @@ RUN curl -fsSL https://deb.nodesource.com/setup_22.x | bash - \
 # Docker CLI + Compose + Buildx (mount socket at runtime for access)
 RUN curl -fsSL https://get.docker.com | sh
 
-# Pull in all available security patches for installed packages.
-RUN apt-get update && apt-get upgrade -y && rm -rf /var/lib/apt/lists/*
 
 WORKDIR /app
 

Dockerfile.alpine

@@ -29,7 +29,7 @@
 #  Compiles Python dependencies in an isolated prefix.  Alpine needs
 #  musl-dev and gcc for most C extensions.
 # --------------------------------------------------------------------------
-FROM python:3.12-alpine AS builder
+FROM python:3.12.13-alpine AS builder
 
 WORKDIR /src
 
@@ -55,7 +55,7 @@ RUN pip install --no-cache-dir --prefix=/install .
 #  Stage 2: Runtime
 #  Tiny Alpine runtime.  No compilers, no build tools, no sudo.
 # --------------------------------------------------------------------------
-FROM python:3.12-alpine
+FROM python:3.12.13-alpine
 
 # ── Runtime system packages ────────────────────────────────────────────────
 #
@@ -94,8 +94,6 @@ COPY --from=builder /install /usr/local
 WORKDIR /app
 COPY . .
 
-# Upgrade base packages to pull in security fixes (e.g. zlib CVE-2026-22184).
-RUN apk upgrade --no-cache
 
 # Install the app itself (fast — all deps are already present) and grant
 # the Python binary cap_setgid so multi-user mode can call setgid().

Dockerfile.slim

@@ -25,7 +25,7 @@
 #  Compiles Python dependencies in an isolated prefix so we can copy only
 #  the final result into the slim runtime image — no compilers shipped.
 # --------------------------------------------------------------------------
-FROM python:3.12-slim AS builder
+FROM python:3.12.13-slim AS builder
 
 WORKDIR /src
 
@@ -51,7 +51,7 @@ RUN pip install --no-cache-dir --prefix=/install .
 #  Stage 2: Runtime
 #  The actual image that ships. No compilers, no build tools, no sudo.
 # --------------------------------------------------------------------------
-FROM python:3.12-slim
+FROM python:3.12.13-slim
 
 # ── Runtime system packages ────────────────────────────────────────────────
 #

README.md

@@ -29,7 +29,7 @@ That's it — you're up and running at `http://localhost:8000`.
 | | `latest` | `slim` | `alpine` |
 |---|---|---|---|
 | **Best for** | AI agent sandboxes | Production / hardened | Edge / CI / minimal footprint |
-| **Size** | ~2 GB | ~500 MB | ~300 MB |
+| **Size** | ~4 GB | ~430 MB | ~230 MB |
 | **Bundled tooling** | Node.js, gcc, ffmpeg, LaTeX, Docker CLI, data science libs | git, curl, jq | git, curl, jq |
 | **Install packages at runtime** | ✔ (has `sudo`) | ✘ | ✘ |
 | **Multi-user / egress firewall** | ✔ | ✔ | ✔ |