Added new mkimage-yum.sh script to create CentOS base images

mkimage-rinse.sh requires rinse, which is not readily available on
CentOS or Fedora.  Plus, creating a base image is trivial with yum
alone.

Docker-DCO-1.1-Signed-off-by: Chris St. Pierre <chris.a.st.pierre@gmail.com> (github: stpierre)

contrib/mkimage-rinse.sh

@@ -1,4 +1,11 @@
 #!/usr/bin/env bash
+#
+# Create a base CentOS Docker image.
+
+# This script is useful on systems with rinse available (e.g.,
+# building a CentOS image on Debian).  See contrib/mkimage-yum.sh for
+# a way to build CentOS images on systems with yum installed.
+
 set -e
 
 repo="$1"

contrib/mkimage-yum.sh

@@ -0,0 +1,90 @@
+#!/bin/bash
+#
+# Create a base CentOS Docker image.
+#
+# This script is useful on systems with yum installed (e.g., building
+# a CentOS image on CentOS).  See contrib/mkimage-rinse.sh for a way
+# to build CentOS images on other systems.
+
+usage() {
+    cat <<EOOPTS
+$(basename $0) [OPTIONS] <name>
+OPTIONS:
+  -y <yumconf>  The path to the yum config to install packages from. The
+                default is /etc/yum.conf.
+EOOPTS
+    exit 1
+}
+
+# option defaults
+yum_config=/etc/yum.conf
+while getopts ":y:h" opt; do
+    case $opt in
+        y)
+            yum_config=$OPTARG
+            ;;
+        h)
+            usage
+            ;;
+        \?)
+            echo "Invalid option: -$OPTARG"
+            usage
+            ;;
+    esac
+done
+shift $((OPTIND - 1))
+name=$1
+
+if [[ -z $name ]]; then
+    usage
+fi
+
+#--------------------
+
+target=$(mktemp -d --tmpdir $(basename $0).XXXXXX)
+
+set -x
+
+for dev in console null zero urandom; do
+    /sbin/MAKEDEV -d "$target"/dev -x $dev
+done
+
+yum -c "$yum_config" --installroot="$target" --setopt=tsflags=nodocs \
+    --setopt=group_package_types=mandatory -y groupinstall Core
+yum -c "$yum_config" --installroot="$mount" -y clean all
+
+cat > "$target"/etc/sysconfig/network <<EOF
+NETWORKING=yes
+HOSTNAME=localhost.localdomain
+EOF
+
+# effectively: febootstrap-minimize --keep-zoneinfo --keep-rpmdb
+# --keep-services "$target".  Stolen from mkimage-rinse.sh
+#  locales
+rm -rf "$target"/usr/{{lib,share}/locale,{lib,lib64}/gconv,bin/localedef,sbin/build-locale-archive}
+#  docs
+rm -rf "$target"/usr/share/{man,doc,info,gnome/help}
+#  cracklib
+rm -rf "$target"/usr/share/cracklib
+#  i18n
+rm -rf "$target"/usr/share/i18n
+#  sln
+rm -rf "$target"/sbin/sln
+#  ldconfig
+rm -rf "$target"/etc/ld.so.cache
+rm -rf "$target"/var/cache/ldconfig/*
+
+version=
+if [ -r "$target"/etc/redhat-release ]; then
+    version="$(sed 's/^[^0-9\]*\([0-9.]\+\).*$/\1/' /etc/redhat-release)"
+fi
+
+if [ -z "$version" ]; then
+    echo >&2 "warning: cannot autodetect OS version, using '$name' as tag"
+    version=$name
+fi
+
+tar --numeric-owner -c -C "$target" . | docker import - $name:$version
+docker run -i -t $name:$version echo success
+
+rm -rf "$target"

docs/sources/articles/baseimages.rst

@@ -37,7 +37,10 @@ There are more example scripts for creating base images in the
 Docker Github Repo:
 
 * `BusyBox <https://github.com/dotcloud/docker/blob/master/contrib/mkimage-busybox.sh>`_
-* `CentOS / Scientific Linux CERN (SLC)
+* CentOS / Scientific Linux CERN (SLC) `on Debian/Ubuntu
   <https://github.com/dotcloud/docker/blob/master/contrib/mkimage-rinse.sh>`_
+  or
+  `on CentOS/RHEL/SLC/etc.
+  <https://github.com/dotcloud/docker/blob/master/contrib/mkimage-yum.sh>`_
 * `Debian / Ubuntu
   <https://github.com/dotcloud/docker/blob/master/contrib/mkimage-debootstrap.sh>`_