[Docker] Move away from legacy ENV assigment

Dockerfile

@@ -9,9 +9,9 @@
 # User guide build environment
 FROM python:3.12.5-slim-bookworm AS user_guide_builder
 
-ENV PYTHONDONTWRITEBYTECODE 1
-ENV PYTHONUNBUFFERED 1
-ENV PIP_NO_CACHE_DIR 1
+ENV PYTHONDONTWRITEBYTECODE=1
+ENV PYTHONUNBUFFERED=1
+ENV PIP_NO_CACHE_DIR=1
 
 WORKDIR /app
 
@@ -40,9 +40,9 @@ FROM nginx:1.27
 
 WORKDIR /app
 
-ENV HOST_DIR /usr/share/nginx
-ENV USER_GUIDE_HOST_DIR ${HOST_DIR}/user_guide
-ENV FRONTEND_HOST_DIR ${HOST_DIR}/html
+ENV HOST_DIR=/usr/share/nginx
+ENV USER_GUIDE_HOST_DIR=${HOST_DIR}/user_guide
+ENV FRONTEND_HOST_DIR=${HOST_DIR}/html
 
 RUN mkdir /etc/nginx/templates
 RUN mkdir /etc/nginx/page_templates

deploy/Dockerfile

@@ -23,8 +23,8 @@ RUN curl -LO "https://dl.k8s.io/release/$(curl -L -s https://dl.k8s.io/release/s
   ./get_helm.sh && \
   rm kubectl get_helm.sh
 
-ENV HOME /root
-ENV PATH ${PATH}:${HOME}/scripts
+ENV HOME=/root
+ENV PATH=${PATH}:${HOME}/scripts
 
 COPY requirements.txt ${HOME}
 RUN pip3 install -r ${HOME}/requirements.txt

maintenance/Dockerfile

@@ -39,7 +39,7 @@ RUN chown user:user ${FONT_DIR}
 USER user
 WORKDIR ${HOME}
 
-ENV PATH ${PATH}:${SCRIPT_DIR}
+ENV PATH=${PATH}:${SCRIPT_DIR}
 
 COPY --chown=user:user requirements.txt .