Make $DIB_YUM_REPO_CONF accept a list of repo files

It's useful to be able to pass in multiple yum repo configuration files
via $DIB_YUM_REPO_CONF, not just a single one.

Change-Id: I43722229a2df58be55bdb2b50c253e957b18e6fe

elements/yum/README.rst

@@ -12,7 +12,8 @@ increases image building speed when building multiple images, especially on
 slow connections.  This is more effective than using an HTTP proxy as a yum
 cache since the same rpm from different mirrors is often requested.
 
-A custom yum repository configuration can also be applied by defining
-`DIB_YUM_REPO_CONF` to the path to a repo configuration file. The file will
-be copied to /etc/yum.repos.d/dib-yum-repo-conf.repo during the image build,
-and then removed at the end of the build.
+Custom yum repository configurations can also be applied by defining
+`DIB_YUM_REPO_CONF` to a space separated list of repo configuration files. The
+files will be copied to /etc/yum.repos.d/ during the image build, and then
+removed at the end of the build. Each repo file should be named differently to
+avoid a filename collision.

elements/yum/cleanup.d/99-remove-yum-repo-conf

@@ -6,4 +6,12 @@ fi
 set -eu
 set -o pipefail
 
-sudo rm -f $TMP_MOUNT_PATH/etc/yum.repos.d/dib-yum-repo-conf.repo
+# exit directly if DIB_YUM_REPO_CONF is not defined properly
+if [ -z "${DIB_YUM_REPO_CONF:-}" ] ; then
+    echo "DIB_YUM_REPO_CONF is not set - no repo configurations will be cleaned up"
+    exit 0
+fi
+
+for file in $DIB_YUM_REPO_CONF; do
+    sudo rm -f $TMP_MOUNT_PATH/etc/yum.repos.d/$(basename $file)
+done

elements/yum/extra-data.d/99-yum-repo-conf

@@ -1,5 +1,5 @@
 #!/bin/bash
-# Add an additional yum repo configuration with $DIB_YUM_REPO_CONF
+# Add additional yum repo configuration(s) with $DIB_YUM_REPO_CONF
 
 if [ ${DIB_DEBUG_TRACE:-1} -gt 0 ]; then
     set -x
@@ -11,11 +11,17 @@ set -o pipefail
 if [ -z "${DIB_YUM_REPO_CONF:-}" ] ; then
     echo "DIB_YUM_REPO_CONF is not set - no repo configuration will be copied in"
     exit 0
-elif [ ! -f "$DIB_YUM_REPO_CONF" ] ; then
-    echo "DIB_YUM_REPO_CONF is not a valid yum repo configuration file."
-    echo "You should assign a proper yum repo configuration file in DIB_YUM_REPO_CONF"
-    exit 1
 fi
 
-# copy the yum repo configuration
-sudo cp -L -f $DIB_YUM_REPO_CONF $TMP_MOUNT_PATH/etc/yum.repos.d/dib-yum-repo-conf.repo
+for file in $DIB_YUM_REPO_CONF; do
+    if [ ! -f $file ]; then
+        echo "$file is not a valid yum repo configuration file."
+        echo "You should assign a list of proper yum repo configuration"
+        echo "files in DIB_YUM_REPO_CONF."
+        exit 1
+    fi
+
+    # copy the yum repo configuration
+    sudo cp -L -f $file $TMP_MOUNT_PATH/etc/yum.repos.d
+
+done