Fix issue with python install

Switched to epics-containers epics-base-developer:7.0.8ec2
Added pcas build
Used python and compilers from epics-base developer stage
Updated to latest (pinned) dockerize python module

Dockerfile

@@ -3,24 +3,28 @@
 FROM alpine AS download-extract
 
 RUN apk update && apk add git
-RUN git clone --branch R2-1-2-0 --depth 1 -c advice.detachedHead=false \
+RUN git clone --branch R2-1-3-0 --depth 1 -c advice.detachedHead=false \
       https://github.com/epics-extensions/ca-gateway.git /ca-gateway
-RUN rm -rf /ca-gateway/.git
+RUN git clone --branch v4.13.3 --depth 1 -c advice.detachedHead=false \
+      https://github.com/epics-modules/pcas.git /epics/support/pcas
+
+RUN rm -rf /ca-gateway/.git; rm -rf /epics/support/pcas/.git
 
 
 ## ===============================
 #  2nd stage: build the CA Gateway
-FROM pklaus/epics_base:7.0.4_debian AS builder
-
-# The scs user already exists in base image.
-# We set it here explicitly to clarify file ownership.
-USER scs
+FROM ghcr.io/epics-containers/epics-base-developer:7.0.8ec2 AS builder
 
 # Download the EPICS CA Gateway
-COPY --chown=scs:users --from=download-extract /ca-gateway /epics/src/ca-gateway
+COPY --from=download-extract /ca-gateway /epics/src/ca-gateway
+COPY --from=download-extract /epics/support/pcas /epics/support/pcas
+
+RUN cd /epics/support/pcas \
+ && echo "EPICS_BASE=/epics/epics-base" > configure/RELEASE.local \
+ && make -j$(nproc)
 RUN cd /epics/src/ca-gateway \
- && echo "EPICS_BASE=/epics/base" > configure/RELEASE.local \
- && echo "PCAS=/epics/base/modules/pcas" >> configure/RELEASE.local \
+ && echo "EPICS_BASE=/epics/epics-base" > configure/RELEASE.local \
+ && echo "PCAS=/epics/support/pcas" >> configure/RELEASE.local \
  && echo "INSTALL_LOCATION=/epics/ca-gateway" > configure/CONFIG_SITE.local \
  && make -j$(nproc)
 
@@ -30,14 +34,13 @@ RUN cd /epics/src/ca-gateway \
 #            to a new root folder. For more information, read
 #            https://blog.oddbit.com/post/2015-02-05-creating-minimal-docker-images/
 FROM builder AS dockerizer
-USER root
 
-# Install Python and a Python2 compatible version of larsks/dockerize
-RUN apt-get update && apt-get install -yq python python-pip rsync \
- && pip install https://github.com/larsks/dockerize/archive/a903419.zip
+# Install the latest commit of dockerize (2021/07/06)
+RUN pip install git+https://github.com/larsks/dockerize@024b1a2
 
 # Move the executable "gateway" to a more prominent location
 RUN mv /epics/ca-gateway/bin/*/gateway /epics/
+RUN useradd scs
 
 # Dockerize
 RUN dockerize -L preserve -n -u scs -o /ca-gateway_root --verbose /epics/gateway \
@@ -53,6 +56,7 @@ ENTRYPOINT ["/epics/gateway"]
 #             from scratch for minimal size.
 FROM scratch AS final
 
+# User scs gives us a non-root user to run the gateway
 USER scs
 
 COPY --from=dockerizer /ca-gateway_root /