diff --git a/Dockerfile.mockbuild b/Dockerfile.mockbuild
index 51d63aa..fdcec8d 100644
--- a/Dockerfile.mockbuild
+++ b/Dockerfile.mockbuild
@@ -1,6 +1,6 @@
 #
 # Copyright 2018-2024 Intel Corporation
-# Copyright 2025 Hewlett Packard Enterprise Development LP
+# Copyright 2025-2026 Hewlett Packard Enterprise Development LP
 #
 # 'recipe' for Docker to build an RPM
 #
@@ -12,37 +12,43 @@ FROM fedora:$FVERSION
 ARG FVERSION
 LABEL maintainer="daos@daos.groups.io"
 
-# Use local repo server if present
-ARG REPO_FILE_URL
-ARG DAOS_LAB_CA_FILE_URL
-ARG REPOSITORY_NAME
-
-# Accept DAOS_NO_PROXY at build time
+# Accept DAOS_HTTP_PROXY, DAOS_HTTPS_PROXY, and DAOS_NO_PROXY at build time
 ARG DAOS_NO_PROXY
-# Propagate into the build environment
-ENV no_proxy=${DAOS_NO_PROXY}
-ENV NO_PROXY=${DAOS_NO_PROXY}
-# Persist into /etc/environment for use by shells and services
-RUN echo "no_proxy=${DAOS_NO_PROXY}" >> /etc/environment && \
-    echo "NO_PROXY=${DAOS_NO_PROXY}" >> /etc/environment
-
-# Accept DAOS_HTTPS_PROXY at build time
+ARG DAOS_HTTP_PROXY
 ARG DAOS_HTTPS_PROXY
+
 # Propagate into the build environment
-ENV https_proxy=${DAOS_HTTPS_PROXY}
-ENV HTTPS_PROXY=${DAOS_HTTPS_PROXY}
+ENV http_proxy=${DAOS_HTTP_PROXY} \
+    HTTP_PROXY=${DAOS_HTTP_PROXY} \
+    https_proxy=${DAOS_HTTPS_PROXY} \
+    HTTPS_PROXY=${DAOS_HTTPS_PROXY} \
+    no_proxy=${DAOS_NO_PROXY} \
+    NO_PROXY=${DAOS_NO_PROXY}
+
 # Persist into /etc/environment for use by shells and services
-RUN echo "https_proxy=${DAOS_HTTPS_PROXY}" >> /etc/environment && \
-    echo "HTTPS_PROXY=${DAOS_HTTPS_PROXY}" >> /etc/environment
+RUN set -e; \
+    if [ -n "$DAOS_HTTP_PROXY" ]; then \
+        echo "http_proxy=$DAOS_HTTP_PROXY" >> /etc/environment; \
+        echo "HTTP_PROXY=$DAOS_HTTP_PROXY" >> /etc/environment; \
+    fi; \
+    if [ -n "$DAOS_HTTPS_PROXY" ]; then \
+        echo "https_proxy=$DAOS_HTTPS_PROXY" >> /etc/environment; \
+        echo "HTTPS_PROXY=$DAOS_HTTPS_PROXY" >> /etc/environment; \
+    fi; \
+    if [ -n "$DAOS_NO_PROXY" ]; then \
+        echo "no_proxy=$DAOS_NO_PROXY" >> /etc/environment; \
+        echo "NO_PROXY=$DAOS_NO_PROXY" >> /etc/environment; \
+    fi
 
-# script to install OS updates basic tools and daos dependencies
-# COPY ./utils/scripts/install-fedora.sh /tmp/install.sh
-# script to setup local repo if available
-COPY ./packaging/scripts/repo-helper-fedora.sh /tmp/repo-helper.sh
+# Use local repo server if present
+ARG REPO_FILE_URL
+ARG DAOS_LAB_CA_FILE_URL
+ARG REPOSITORY_NAME
 
-RUN chmod +x /tmp/repo-helper.sh && \
-    /tmp/repo-helper.sh &&          \
-    rm -f /tmp/repo-helper.sh
+# Script to setup a local repo instead of the distro-provided one.
+# Only takes effect when REPO_FILE_URL is set; otherwise it is a no-op.
+RUN --mount=type=bind,source=packaging/scripts/repo-helper-fedora.sh,target=/tmp/repo-helper-fedora.sh \
+    /tmp/repo-helper-fedora.sh
 
 # Install basic tools
 RUN dnf -y install mock make rpm-build createrepo rpmlint git \
diff --git a/Dockerfile.ubuntu.20.04 b/Dockerfile.ubuntu.20.04
index bd5363b..4484c84 100644
--- a/Dockerfile.ubuntu.20.04
+++ b/Dockerfile.ubuntu.20.04
@@ -3,7 +3,7 @@
 # Jenkinsfile will be changed to use Dockerfile.ubuntu.
 #
 # Copyright 2019-2021, Intel Corporation
-# Copyright 2025 Hewlett Packard Enterprise Development LP
+# Copyright 2025-2026 Hewlett Packard Enterprise Development LP
 #
 # 'recipe' for Docker to build an Debian package
 #
@@ -14,15 +14,41 @@ LABEL org.opencontainers.image.authors="daos@daos.groups.io"
 # Needed for later use of BASE_DISTRO
 ARG BASE_DISTRO
 
+# Accept DAOS_HTTP_PROXY, DAOS_HTTPS_PROXY, and DAOS_NO_PROXY at build time
+ARG DAOS_NO_PROXY
+ARG DAOS_HTTP_PROXY
+ARG DAOS_HTTPS_PROXY
+
+# Propagate into the build environment
+ENV http_proxy=${DAOS_HTTP_PROXY} \
+    HTTP_PROXY=${DAOS_HTTP_PROXY} \
+    https_proxy=${DAOS_HTTPS_PROXY} \
+    HTTPS_PROXY=${DAOS_HTTPS_PROXY} \
+    no_proxy=${DAOS_NO_PROXY} \
+    NO_PROXY=${DAOS_NO_PROXY}
+
+# Persist into /etc/environment for use by shells and services
+RUN set -e; \
+    if [ -n "$DAOS_HTTP_PROXY" ]; then \
+        echo "http_proxy=$DAOS_HTTP_PROXY" >> /etc/environment; \
+        echo "HTTP_PROXY=$DAOS_HTTP_PROXY" >> /etc/environment; \
+    fi; \
+    if [ -n "$DAOS_HTTPS_PROXY" ]; then \
+        echo "https_proxy=$DAOS_HTTPS_PROXY" >> /etc/environment; \
+        echo "HTTPS_PROXY=$DAOS_HTTPS_PROXY" >> /etc/environment; \
+    fi; \
+    if [ -n "$DAOS_NO_PROXY" ]; then \
+        echo "no_proxy=$DAOS_NO_PROXY" >> /etc/environment; \
+        echo "NO_PROXY=$DAOS_NO_PROXY" >> /etc/environment; \
+    fi
+    
 ARG REPO_FILE_URL
 ARG DAOS_LAB_CA_FILE_URL
 ARG REPOSITORY_NAME
-# script to setup local repo if available
-COPY ./packaging/scripts/repo-helper-ubuntu.sh /tmp/repo-helper.sh
-
-RUN chmod +x /tmp/repo-helper.sh &&                 \
-    /tmp/repo-helper.sh &&                          \
-    rm -f /tmp/repo-helper.sh
+# Script to setup a local repo instead of the distro-provided one.
+# Only takes effect when REPO_FILE_URL is set; otherwise it is a no-op.
+RUN --mount=type=bind,source=packaging/scripts/repo-helper-ubuntu.sh,target=/tmp/repo-helper-ubuntu.sh \
+    /tmp/repo-helper-ubuntu.sh
 
 # Install basic tools - rpmdevtools temporary commented out.
 RUN apt-get update && DEBIAN_FRONTEND=noninteractive apt-get install -y \
diff --git a/scripts/repo-helper-fedora.sh b/scripts/repo-helper-fedora.sh
old mode 100644
new mode 100755
index 028575f..f7d4a4f
--- a/scripts/repo-helper-fedora.sh
+++ b/scripts/repo-helper-fedora.sh
@@ -1,4 +1,9 @@
 #!/bin/bash
+#
+#  Copyright 2025-2026 Hewlett Packard Enterprise Development LP
+#
+#  SPDX-License-Identifier: BSD-2-Clause-Patent
+#
 set -uex
 
 # This script is used by Dockerfiles to optionally use
diff --git a/scripts/repo-helper-ubuntu.sh b/scripts/repo-helper-ubuntu.sh
old mode 100644
new mode 100755