Adding multibuild stage

Dockerfile

@@ -1,5 +1,29 @@
-# syntax = docker/dockerfile:1.0-experimental
-FROM centos:7
+# syntax = docker/dockerfile:1
+
+FROM centos:7 as buildenv
+
+# install Docker
+RUN yum install -y yum-utils python3
+RUN yum-config-manager --add-repo https://download.docker.com/linux/centos/docker-ce.repo
+RUN yum install -y docker-ce docker-ce-cli containerd.io docker-compose-plugin
+
+#install Dirac UI
+WORKDIR /root
+RUN mkdir dirac_ui
+WORKDIR /root/dirac_ui
+RUN curl -LO https://github.com/DIRACGrid/DIRACOS2/releases/latest/download/DIRACOS-Linux-$(uname -m).sh
+RUN bash DIRACOS-Linux-$(uname -m).sh
+RUN rm DIRACOS-Linux-$(uname -m).sh
+RUN source diracos/diracosrc && pip install DIRAC==7.3.26
+
+COPY startup.sh /root/startup.sh
+CMD ["/bin/bash", "--init-file", "/root/startup.sh"]
+
+
+
+
+
+FROM centos:7 as dirac_ui
 ARG dirac_version=7.3.26
 
 RUN mkdir /root/dirac_ui