Make ROCKY_MIRROR_URLS a comma separated string

Author: m-bull

elements/rocky-container-stackhpc/containerfiles/9-stackhpc

@@ -1,6 +1,16 @@
 # Based on https://github.com/openstack/diskimage-builder/blob/master/diskimage_builder/elements/rocky-container/containerfiles/9
 
 FROM docker.io/rockylinux/rockylinux:9
+ARG ROCKY_USE_MIRRORS=false
+# Comma separated list of repo URLS
+ARG ROCKY_MIRROR_URLS
+
+RUN if [[ ${ROCKY_USE_MIRRORS} = "true" ]]; then \
+    dnf -y install 'dnf-command(config-manager)' && \
+    mkdir /tmp/orig_repos && mv -f /etc/yum.repos.d/* /tmp/orig_repos/ && \
+    for REPO_URL in $(echo ${ROCKY_MIRROR_URLS} | sed "s/,/ /g"); do \
+        dnf config-manager --add-repo ${REPO_URL}; done && \
+    dnf --allowerasing -y distro-sync; fi
 
 RUN dnf group install -y 'Minimal Install' --allowerasing && \
     dnf install -y findutils util-linux cloud-init