diff --git a/scripts/build.sh b/scripts/build.sh
index ae6e6f3..304102b 100755
--- a/scripts/build.sh
+++ b/scripts/build.sh
@@ -15,6 +15,9 @@
 
 set -euxo pipefail
 
+SCRIPT_PATH=$(readlink -f "$0")
+SCRIPT_DIR=$(dirname -- "${SCRIPT_PATH}")
+
 if [[ "$#" -lt 1 || "${1}" != "--arm64" && "${1}" != "--amd64" ]]; then
     echo "Error: First parameter must be --arm64 or --amd64."
     exit 1
@@ -46,6 +49,9 @@ for LABEL in "${LABELS[@]}"; do
     IMAGES+=("--image-name \"ghcr.io/eclipse-score/devcontainer:${LABEL}-${ARCH}\"")
 done
 
+. "${SCRIPT_DIR}/functions.sh"
+set_dockerfile_name
+
 # Prepare devcontainer build command
 DEVCONTAINER_CALL="devcontainer build --workspace-folder src/s-core-devcontainer --cache-from ghcr.io/eclipse-score/devcontainer"
 
diff --git a/scripts/functions.sh b/scripts/functions.sh
new file mode 100755
index 0000000..8d83da3
--- /dev/null
+++ b/scripts/functions.sh
@@ -0,0 +1,29 @@
+#!/bin/bash
+
+# *******************************************************************************
+# Copyright (c) 2026 Contributors to the Eclipse Foundation
+#
+# See the NOTICE file(s) distributed with this work for additional
+# information regarding copyright ownership.
+#
+# This program and the accompanying materials are made available under the
+# terms of the Apache License Version 2.0 which is available at
+# https://www.apache.org/licenses/LICENSE-2.0
+#
+# SPDX-License-Identifier: Apache-2.0
+# *******************************************************************************
+
+set_dockerfile_name() {
+    DEVCONTAINER_DOCKERFILE_NAME="Dockerfile"
+
+    # Check if proxies are configured in the environment
+    set +u
+    if [ -n "${HTTP_PROXY}${HTTPS_PROXY}${http_proxy}${https_proxy}${NO_PROXY}${no_proxy}" ]; then
+        DEVCONTAINER_DOCKERFILE_NAME="Dockerfile-with-proxy-vars"
+        echo "Proxy environment detected."
+    fi
+    set -u
+
+    export DEVCONTAINER_DOCKERFILE_NAME
+    echo "Using Dockerfile: ${DEVCONTAINER_DOCKERFILE_NAME}"
+}
diff --git a/scripts/test.sh b/scripts/test.sh
index c16563b..969d7f0 100755
--- a/scripts/test.sh
+++ b/scripts/test.sh
@@ -24,6 +24,9 @@ SCRIPT_DIR=$(dirname -- "${SCRIPT_PATH}")
 PROJECT_DIR=$(dirname -- "${SCRIPT_DIR}")
 ID_LABEL="test-container=${IMAGE}"
 
+. "${SCRIPT_DIR}/functions.sh"
+set_dockerfile_name
+
 devcontainer up \
   --id-label "${ID_LABEL}" \
   --workspace-folder "${PROJECT_DIR}/src/${IMAGE}/" \
diff --git a/src/s-core-devcontainer/.devcontainer/Dockerfile b/src/s-core-devcontainer/.devcontainer/Dockerfile
index 6589b2f..692412c 100644
--- a/src/s-core-devcontainer/.devcontainer/Dockerfile
+++ b/src/s-core-devcontainer/.devcontainer/Dockerfile
@@ -1,24 +1,5 @@
 FROM buildpack-deps:noble-curl
 
-# Proxy arguments for build-time network access
-ARG HTTP_PROXY=""
-ARG HTTPS_PROXY=""
-ARG http_proxy=""
-ARG https_proxy=""
-ARG NO_PROXY=""
-ARG no_proxy=""
-
-# Set proxy environment variables for the build process
-ENV HTTP_PROXY=${HTTP_PROXY}
-ENV HTTPS_PROXY=${HTTPS_PROXY}
-ENV http_proxy=${http_proxy}
-ENV https_proxy=${https_proxy}
-ENV NO_PROXY=${NO_PROXY}
-ENV no_proxy=${no_proxy}
-
 LABEL dev.containers.features="common"
 
-# Unset proxy variables for all login shells
-COPY unset-proxy.sh /etc/profile.d/unset-proxy.sh
-
 RUN userdel -f -r ubuntu
diff --git a/src/s-core-devcontainer/.devcontainer/Dockerfile-with-proxy-vars b/src/s-core-devcontainer/.devcontainer/Dockerfile-with-proxy-vars
new file mode 100644
index 0000000..2e59f67
--- /dev/null
+++ b/src/s-core-devcontainer/.devcontainer/Dockerfile-with-proxy-vars
@@ -0,0 +1,24 @@
+FROM buildpack-deps:noble-curl
+
+# Proxy arguments for build-time network access
+ARG HTTP_PROXY=""
+ARG HTTPS_PROXY=""
+ARG http_proxy=""
+ARG https_proxy=""
+ARG NO_PROXY=""
+ARG no_proxy=""
+
+# Set proxy environment variables for the build process
+ENV HTTP_PROXY=${HTTP_PROXY}
+ENV HTTPS_PROXY=${HTTPS_PROXY}
+ENV http_proxy=${http_proxy}
+ENV https_proxy=${https_proxy}
+ENV NO_PROXY=${NO_PROXY}
+ENV no_proxy=${no_proxy}
+
+LABEL dev.containers.features="common"
+
+# Unset proxy variables for all login shells
+COPY unset-proxy.sh /etc/bash_completion.d/unset-proxy.sh
+
+RUN userdel -f -r ubuntu
diff --git a/src/s-core-devcontainer/.devcontainer/devcontainer.json b/src/s-core-devcontainer/.devcontainer/devcontainer.json
index 183be4d..8d9438d 100644
--- a/src/s-core-devcontainer/.devcontainer/devcontainer.json
+++ b/src/s-core-devcontainer/.devcontainer/devcontainer.json
@@ -1,7 +1,7 @@
 {
     "build": {
         // Installs latest version from the Distribution
-        "dockerfile": "./Dockerfile",
+        "dockerfile": "./${localEnv:DEVCONTAINER_DOCKERFILE_NAME:Dockerfile}",
         "context": ".",
         "args": {
             "HTTP_PROXY": "${localEnv:HTTP_PROXY}",
diff --git a/src/s-core-devcontainer/.devcontainer/unset-proxy.sh b/src/s-core-devcontainer/.devcontainer/unset-proxy.sh
index 2a9a0ea..fd7900a 100755
--- a/src/s-core-devcontainer/.devcontainer/unset-proxy.sh
+++ b/src/s-core-devcontainer/.devcontainer/unset-proxy.sh
@@ -13,7 +13,7 @@
 # SPDX-License-Identifier: Apache-2.0
 # *******************************************************************************
 
-# /etc/profile.d/unset-proxy.sh
+# /etc/bash_completion.d/unset-proxy.sh
 # Unset proxy variables for all login shells if they are empty
 for var in HTTP_PROXY HTTPS_PROXY http_proxy https_proxy NO_PROXY no_proxy; do
     if [ -z "${!var}" ]; then
diff --git a/src/s-core-devcontainer/test-project/test.sh b/src/s-core-devcontainer/test-project/test.sh
index dadb958..83b7b44 100755
--- a/src/s-core-devcontainer/test-project/test.sh
+++ b/src/s-core-devcontainer/test-project/test.sh
@@ -15,7 +15,10 @@
 
 set -euo pipefail
 
-source "test-utils.sh" vscode
+SCRIPT_PATH=$(readlink -f "$0")
+SCRIPT_DIR=$(dirname -- "${SCRIPT_PATH}")
+
+source "${SCRIPT_DIR}/test-utils.sh" vscode
 
 # C++ tooling
 check "validate clangd is working and has the correct version" bash -c "clangd --version | grep '20.1.8'"
@@ -36,5 +39,14 @@ source /devcontainer/features/s-core-local/tests/test_default.sh
 # Tests from the local bazel feature
 source /devcontainer/features/bazel/tests/test_default.sh
 
+# Check that no environment variables are empty
+. /etc/bash_completion
+for var in $(compgen -e); do
+    if [[ "${var}" == "LS_COLORS" ]]; then
+        continue
+    fi
+    check "validate environment variable ${var} is not empty" bash -c "[ -n \"\${${var}}\" ]"
+done
+
 # Report result
 reportResults