[lxc-devel] [RFC] [PATCH] lxc-fedora template - Add --fqdn option for utsname.

[Michael H. Warfield]

All,

After comments from Serge, attached is a suggested patch to the Fedora
template to incorporate the FQDN (Fully Qualified Domain Name) of the
container as the utsname in the container configuration and in the host
name of the system.  It adds a "--fqdn" long option to explicitly
specify the value for utsname and hostname.

The logic contains one default behavior change.  If an FQDN is not
specified or is a host simple name, the logic will use the domain name
of the host appended to either the container name or the simple name to
generate an FQDN.

There were some comments on the -users list about determining the name
of a container based on it's host name.  That's never a good idea
anyways because they can be independently changed but this would also
change the default case.  Please looks that over and comment.  Other
container owners might consider a similar modification.

Regards,
Mike
-- 
Michael H. Warfield (AI4NB) | (770) 985-6132 |  mhw at WittsEnd.com
   /\/\|=mhw=|\/\/          | (678) 463-0932 |  http://www.wittsend.com/mhw/
   NIC whois: MHW9          | An optimist believes we live in the best of all
 PGP Key: 0x674627FF        | possible worlds.  A pessimist is sure of it!
-- 

Signed-off-by: Michael H. Warfield <mhw at WittsEnd.com>

--- 
diff --git a/templates/lxc-fedora.in b/templates/lxc-fedora.in
index 481f718..8cc1699 100644
--- a/templates/lxc-fedora.in
+++ b/templates/lxc-fedora.in
@@ -66,7 +66,7 @@ configure_fedora()
 DEVICE=eth0
 BOOTPROTO=dhcp
 ONBOOT=yes
-HOSTNAME=${name}
+HOSTNAME=${utsname}
 NM_CONTROLLED=no
 TYPE=Ethernet
 MTU=${MTU}
@@ -75,17 +75,17 @@ EOF
     # set the hostname
     cat <<EOF > ${rootfs_path}/etc/sysconfig/network
 NETWORKING=yes
-HOSTNAME=${name}
+HOSTNAME=${utsname}
 EOF
 
     # set hostname on systemd Fedora systems
     if [ $release -gt 14 ]; then
-        echo "${name}" > ${rootfs_path}/etc/hostname
+        echo "${utsname}" > ${rootfs_path}/etc/hostname
     fi
 
     # set minimal hosts
     cat <<EOF > $rootfs_path/etc/hosts
-127.0.0.1 localhost $name
+127.0.0.1 localhost.localdomain localhost $utsname
 ::1                 localhost6.localdomain6 localhost6
 EOF
 
@@ -287,7 +287,7 @@ copy_configuration()
     mkdir -p $config_path
     grep -q "^lxc.rootfs" $config_path/config 2>/dev/null || echo "lxc.rootfs = $rootfs_path" >> $config_path/config
     cat <<EOF >> $config_path/config
-lxc.utsname = $name
+lxc.utsname = $utsname
 lxc.tty = 4
 lxc.pts = 1024
 lxc.mount = $config_path/fstab
@@ -355,7 +355,7 @@ usage()
     cat <<EOF
 usage:
     $1 -n|--name=<container_name>
-        [-p|--path=<path>] [-c|--clean] [-R|--release=<Fedora_release>] [-A|--arch=<arch of the container>]
+        [-p|--path=<path>] [-c|--clean] [-R|--release=<Fedora_release>] [--fqdn=<network name of container>] [-A|--arch=<arch of the container>]
         [-h|--help]
 Mandatory args:
   -n,--name         container name, used to as an identifier for that container from now on
@@ -363,13 +363,14 @@ Optional args:
   -p,--path         path to where the container rootfs will be created, defaults to @LXCPATH at . The container config will go under @LXCPATH@ in that case
   -c,--clean        clean the cache
   -R,--release      Fedora release for the new container. if the host is Fedora, then it will default to the host's release.
+     --fqdn         fully qualified domain name (FQDN) for DNS and system naming
   -A,--arch         NOT USED YET. Define what arch the container will be [i686,x86_64]
   -h,--help         print this help
 EOF
     return 0
 }
 
-options=$(getopt -o hp:n:cR: -l help,path:,name:,clean,release: -- "$@")
+options=$(getopt -o hp:n:cR: -l help,path:,name:,clean,release:,fqdn: -- "$@")
 if [ $? -ne 0 ]; then
     usage $(basename $0)
     exit 1
@@ -384,6 +385,7 @@ do
         -n|--name)      name=$2; shift 2;;
         -c|--clean)     clean=$2; shift 2;;
         -R|--release)   release=$2; shift 2;;
+        --fqdn)         utsname=$2; shift 2;;
         --)             shift 1; break ;;
         *)              break ;;
     esac
@@ -394,6 +396,29 @@ if [ ! -z "$clean" -a -z "$path" ]; then
     exit 0
 fi
 
+if [ -z "${utsname}" ]; then
+    utsname=${name}
+fi
+
+# This follows a standard "resolver" convention that an FQDN must have
+# at least two dots or it is considered a local relative host name.
+# If it doesn't, append the dns domain name of the host system.
+#
+# This changes one significant behavior when running
+# "lxc_create -n Container_Name" without using the
+# --fqdn option.
+#
+# Old behavior:
+#    utsname and hostname = Container_Name
+# New behavior:
+#    utsname and hostname = Container_Name.Domain_Name
+
+if [ $(expr "$utsname" : '.*\..*\.') = 0 ]; then
+    if [ -n "$(dnsdomainname)" ]; then
+        utsname=${utsname}.$(dnsdomainname)
+    fi
+fi
+
 needed_pkgs=""
 type yum >/dev/null 2>&1
 if [ $? -ne 0 ]; then

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