Add support for Alpine Linux 3

Based on xenserver#53

mk/install.sh

@@ -137,6 +137,9 @@ select_pkgs_rhel()
 	rhel8|centos8|oracle8|scientific8|neokylin8)
 	    # No additional kernel package
 	    ;;
+	alpine3*)
+	    # No additional kernel package
+	    ;;
 	rhel3|fedora*)
 	    # Not officially supported therefore no additional packages required.
 	    ;;
@@ -510,6 +513,7 @@ install_coreos()
 case "${os_distro}" in
     rhel|centos|oracle|fedora)         select_pkgs_rhel ;;
     scientific|neokylin|asianux|turbo) select_pkgs_rhel ;;
+    alpine)                            select_pkgs_rhel ;;
     sles|"suse linux")                 select_pkgs_sles ;;
     debian|ubuntu|linx|yinhe)          select_pkgs_debian ;;
     xe-ddk|xe-sdk)                     select_pkgs_xe ;;

mk/xe-linux-distribution

@@ -494,6 +494,23 @@ identify_boot2docker()
 
 }
 
+identify_alpine()
+{
+    # only tested with Alpine 3.7+
+    alpine_release="$1"
+    local major
+    local minor
+
+    if [ ! -f "${alpine_release}" ]; then
+        return 1
+    fi
+
+    major=$(awk -F. '{printf("%s", $1)}' ${alpine_release})
+    minor=$(awk -F. '{printf("%s.%s", $2, $3)}' ${alpine_release})
+
+    write_to_output "alpine" "${major}" "${minor}" "Alpine Linux $(head -n 1 ${alpine_release})"
+}
+
 if [ $# -eq 1 ] ; then
     exec 1>"$1"
 fi
@@ -517,6 +534,7 @@ if [ -z "${TEST}" ] ; then
     identify_lsb lsb_release         && exit 0
     identify_debian /etc/debian_version && exit 0
     identify_boot2docker /etc/boot2docker && exit 0
+    identify_alpine /etc/alpine-release && exit 0
 
 
     if [ $# -eq 1 ] ; then