fix(conpot): use honeynet/conpot:latest base, run as conpot user

The BASE_IMAGE build arg was being unconditionally overwritten by
composer.py with the decky's distro build_base (debian:bookworm-slim),
turning the conpot container into a bare Debian image with no conpot
installation — hence the silent restart loop.

Two fixes:
1. composer.py: use args.setdefault() so services that pre-declare
   BASE_IMAGE in their compose_fragment() win over the distro default.
2. conpot.py: pre-declare BASE_IMAGE=honeynet/conpot:latest in build
   args so it always uses the upstream image regardless of decky distro.

Also removed the USER decnet switch from the conpot Dockerfile. The
upstream image already runs as the non-root 'conpot' user; switching to
'decnet' broke pkg_resources because conpot's eggs live under
/home/conpot/.local and are only on sys.path for that user.

decnet/composer.py

@@ -69,8 +69,11 @@ def generate_compose(config: DecnetConfig) -> dict:
 
             # Inject the per-decky base image into build services so containers
             # vary by distro and don't all fingerprint as debian:bookworm-slim.
+            # Services that need a fixed upstream image (e.g. conpot) can pre-set
+            # build.args.BASE_IMAGE in their compose_fragment() to opt out.
             if "build" in fragment:
-                fragment["build"].setdefault("args", {})["BASE_IMAGE"] = decky.build_base
+                args = fragment["build"].setdefault("args", {})
+                args.setdefault("BASE_IMAGE", decky.build_base)
 
             fragment.setdefault("environment", {})
             fragment["environment"]["HOSTNAME"] = decky.hostname

decnet/services/conpot.py

@@ -1,4 +1,3 @@
-import os
 from pathlib import Path
 from decnet.services.base import BaseService
 
@@ -24,7 +23,8 @@ class ConpotService(BaseService):
 
         return {
             "build": {
-                "context": str(self.dockerfile_context())
+                "context": str(self.dockerfile_context()),
+                "args": {"BASE_IMAGE": "honeynet/conpot:latest"},
             },
             "container_name": f"{decky_name}-conpot",
             "restart": "unless-stopped",

templates/conpot/Dockerfile

@@ -3,21 +3,16 @@ FROM ${BASE_IMAGE}
 
 USER root
 
-# Replace 5020 with 502 in all templates
+# Replace 5020 with 502 in all templates so Modbus binds on the standard port
 RUN find /opt /usr /etc /home -name "*.xml" -exec sed -i 's/<port>5020<\/port>/<port>502<\/port>/g' {} + 2>/dev/null || true
 RUN find /opt /usr /etc /home -name "*.xml" -exec sed -i 's/port="5020"/port="502"/g' {} + 2>/dev/null || true
 
-# Install libcap to allow binding to 502
+# Install libcap and give the Python interpreter permission to bind ports < 1024
 RUN (apt-get update && apt-get install -y --no-install-recommends libcap2-bin 2>/dev/null) || (apk add --no-cache libcap 2>/dev/null) || true
+RUN find /home/conpot/.local/bin /usr /opt -type f -name 'python*' -exec setcap 'cap_net_bind_service+eip' {} \; 2>/dev/null || true
 
-# Apply setcap to python binaries
-RUN find /usr /opt -type f -name 'python*' -exec setcap 'cap_net_bind_service+eip' {} \; 2>/dev/null || true
-
-# Create the decnet user following repository conventions
-RUN (addgroup -S decnet && adduser -S decnet -G decnet 2>/dev/null) || useradd -r -s /bin/false decnet 2>/dev/null || true
-
-# Make sure all conpot-related directories are owned by decnet so it can run it
-RUN chown -R decnet:decnet /var/log/conpot /opt/conpot /home/conpot /usr/local/lib/python*/site-packages/conpot/tests/data /tmp 2>/dev/null || true
-
-# Run as decnet user, avoiding the root-check failure and 777 hacks
-USER decnet
+# The upstream image already runs as the non-root 'conpot' user.
+# We do NOT switch to a 'decnet' user here — doing so breaks pkg_resources
+# because conpot's eggs live under /home/conpot/.local and are only on the
+# Python path when the interpreter runs as 'conpot'.
+USER conpot