Feature: propagate resolved secrets to interactive container shells (#14254)

docker exec bash bypasses s6, so *_FILE secrets resolved by init-env-file
into /run/s6/container_environment aren't visible even though s6 services
and management wrappers already see them via with-contenv.

Add /etc/profile.d/contenv.sh, sourced by both login and non-login
interactive bash shells, to export those resolved values into the shell.

Dockerfile

@@ -171,7 +171,9 @@ RUN set -eux \
         && cp /etc/ImageMagick-6/paperless-policy.xml /etc/ImageMagick-6/policy.xml \
       && echo "Cleaning up image layer" \
         && rm --force --verbose *.deb \
-    && rm --recursive --force --verbose /var/lib/apt/lists/*
+    && rm --recursive --force --verbose /var/lib/apt/lists/* \
+    && echo "Configuring interactive shells to source the s6 container environment" \
+      && echo '. /etc/profile.d/contenv.sh' >> /etc/bash.bashrc
 
 WORKDIR /usr/src/paperless/src/
 

docker/rootfs/etc/profile.d/contenv.sh

@@ -0,0 +1,18 @@
+#!/bin/sh
+# Source s6 container environment for interactive shells.
+# Ensures variables resolved from *_FILE secret injection are visible
+# when using 'docker exec bash'. Does not affect s6 services (those
+# use with-contenv directly). Has no effect in non-container contexts
+# because the directory will not exist.
+# Note: sh/dash shells opened via 'docker exec sh' are not covered;
+# only bash-based sessions benefit from this file.
+_pngx_contenv="/run/s6/container_environment"
+if [ -d "${_pngx_contenv}" ]; then
+	for _pngx_f in "${_pngx_contenv}"/*; do
+		[ -f "${_pngx_f}" ] || continue
+		_pngx_name=$(basename "${_pngx_f}")
+		_pngx_val=$(cat "${_pngx_f}")
+		export "${_pngx_name}=${_pngx_val}"
+	done
+fi
+unset _pngx_contenv _pngx_f _pngx_name _pngx_val