krb5: support environment setting on systemd

Let krb5 support environment setting on systemd startup.
Here is one requirement of environment setting from upstream krb5
...
https://web.mit.edu/kerberos/krb5-1.16/doc/admin/conf_files/kdc_conf.html
|Normally, the kdc.conf file is found in the KDC state directory,
LOCALSTATEDIR/krb5kdc. You can override the default location by
setting the environment variable KRB5_KDC_PROFILE.
...

The fix of (krb5-admin-server.service/krb5-kdc.service) refers ubuntu 1604

Variable RUN_KADMIND is sysvinit, move it out from default/krb5-admin-server

Signed-off-by: Hongxu Jia <hongxu.jia@windriver.com>
Signed-off-by: Armin Kuster <akuster808@gmail.com>

meta-oe/recipes-connectivity/krb5/krb5/etc/default/krb5-admin-server

@@ -1,6 +1,4 @@
 # Automatically generated.  If you change anything in this file other than the
-# values of RUN_KADMIND or DAEMON_ARGS, first run dpkg-reconfigure
+# values of DAEMON_ARGS, first run dpkg-reconfigure
 # krb5-admin-server and disable managing the kadmin configuration with
 # debconf.  Otherwise, changes will be overwritten.
-
-RUN_KADMIND=true

meta-oe/recipes-connectivity/krb5/krb5/krb5-admin-server.service

@@ -7,6 +7,7 @@ ConditionPathExists=/etc/krb5.conf
 Type=forking
 ExecStartPre=/bin/sh -c "test ! -f /var/log/kadmind.log || test ! -x /sbin/restorecon || /sbin/restorecon -F /var/log/kadmind.log"
 ExecStart=/usr/sbin/kadmind
+EnvironmentFile=-/etc/default/krb5-admin-server
 SuccessExitStatus=1 2 SIGKILL
 TimeoutStopSec=30
 

meta-oe/recipes-connectivity/krb5/krb5/krb5-kdc.service

@@ -6,6 +6,7 @@ ConditionPathExists=/etc/krb5.conf
 [Service]
 Type=forking
 ExecStart=/usr/sbin/krb5kdc
+EnvironmentFile=-/etc/default/krb5-kdc
 SuccessExitStatus=1 2 SIGKILL
 TimeoutStopSec=30
 

meta-oe/recipes-connectivity/krb5/krb5_1.16.bb

@@ -78,12 +78,17 @@ do_install_append() {
         mkdir -p ${D}/${sysconfdir}/default/volatiles
         echo "d root root 0755 ${localstatedir}/run/krb5kdc none" \
               > ${D}${sysconfdir}/default/volatiles/87_krb5
+
+        echo "RUN_KADMIND=true" >> ${D}/${sysconfdir}/default/krb5-admin-server
     fi
     if ${@bb.utils.contains('DISTRO_FEATURES', 'systemd', 'true', 'false', d)}; then
         install -d ${D}${sysconfdir}/tmpfiles.d
         echo "d /run/krb5kdc - - - -" \
               > ${D}${sysconfdir}/tmpfiles.d/krb5.conf
 
+        mkdir -p ${D}/${sysconfdir}/default
+        install -m 0644 ${WORKDIR}/etc/default/* ${D}/${sysconfdir}/default
+
         install -d ${D}${systemd_system_unitdir}
         install -m 0644 ${WORKDIR}/krb5-admin-server.service ${D}${systemd_system_unitdir}
         install -m 0644 ${WORKDIR}/krb5-kdc.service ${D}${systemd_system_unitdir}