diff --git a/bin/prepare_test_env.sh b/bin/prepare_test_env.sh
index 4773cac..605d199 100755
--- a/bin/prepare_test_env.sh
+++ b/bin/prepare_test_env.sh
@@ -66,7 +66,7 @@ $SUDO rm -rf /srv/{salt,pillar}
 $SUDO ln -s $PWD/salt /srv/salt
 $SUDO ln -s $PWD/pillar /srv/pillar
 ID=$(hostname -f)
-printf "grains:\n  city: nuremberg\n  country: de\n  hostusage: test\n  salt_cluster: $SALT_CLUSTER\n  virt_cluster: $VIRT_CLUSTER\n" > pillar/id/${ID//./_}.sls
+printf "grains:\n  city: nuremberg\n  country: de\n  hostusage: test\n  reboot_safe: no\n  salt_cluster: $SALT_CLUSTER\n  virt_cluster: $VIRT_CLUSTER\n" > pillar/id/${ID//./_}.sls
 if [[ -n $HIGHSTATE ]]; then
     ROLES=$(bin/get_roles.py -o yaml)
     [[ -n $OS ]] && OS_GRAINS="osfullname: ${OS[0]}\nosmajorrelease: ${OS[1]}\nosrelease_info: [${OS[1]}, ${OS[2]}]\n"
diff --git a/bin/test_custom_grains.py b/bin/test_custom_grains.py
index 62e48f8..40e705a 100755
--- a/bin/test_custom_grains.py
+++ b/bin/test_custom_grains.py
@@ -33,7 +33,7 @@ def test_custom_grain(mygrains, sls, key, valid_values, status):
             status = error_msg(sls, key, valid_values)
     else:
         if valid_values and value not in valid_values:
-            status = error_msg(sls, key, valid_values)
+            status = error_msg(sls, key, map(str, valid_values))
 
     return status
 
diff --git a/pillar/id/anna_infra_opensuse_org.sls b/pillar/id/anna_infra_opensuse_org.sls
index f447da4..cb36d0f 100644
--- a/pillar/id/anna_infra_opensuse_org.sls
+++ b/pillar/id/anna_infra_opensuse_org.sls
@@ -11,6 +11,7 @@ grains:
     - proxy
     - proxy_master
     - ntp
+  reboot_safe: unknown
   salt_cluster: opensuse
   virt_cluster: atreju
   subrole_ntp: ntp2
diff --git a/pillar/id/baloo_infra_opensuse_org.sls b/pillar/id/baloo_infra_opensuse_org.sls
index 8a1c15a..3726253 100644
--- a/pillar/id/baloo_infra_opensuse_org.sls
+++ b/pillar/id/baloo_infra_opensuse_org.sls
@@ -5,5 +5,6 @@ grains:
     - lists.o.o
   roles:
     - lists
+  reboot_safe: unknown
   salt_cluster: opensuse
   virt_cluster: atreju
diff --git a/pillar/id/boosters_infra_opensuse_org.sls b/pillar/id/boosters_infra_opensuse_org.sls
index ac01f4a..7aea871 100644
--- a/pillar/id/boosters_infra_opensuse_org.sls
+++ b/pillar/id/boosters_infra_opensuse_org.sls
@@ -3,5 +3,6 @@ grains:
   country: de
   hostusage:
     - connect.o.o
+  reboot_safe: unknown
   salt_cluster: opensuse
   virt_cluster: atreju
diff --git a/pillar/id/chip_infra_opensuse_org.sls b/pillar/id/chip_infra_opensuse_org.sls
index e4bba40..4ea37bd 100644
--- a/pillar/id/chip_infra_opensuse_org.sls
+++ b/pillar/id/chip_infra_opensuse_org.sls
@@ -6,5 +6,6 @@ grains:
   roles:
     - ns
     - ns_slave
+  reboot_safe: unknown
   salt_cluster: opensuse
   virt_cluster: atreju
diff --git a/pillar/id/community_infra_opensuse_org.sls b/pillar/id/community_infra_opensuse_org.sls
index 0c72465..d3c46cb 100644
--- a/pillar/id/community_infra_opensuse_org.sls
+++ b/pillar/id/community_infra_opensuse_org.sls
@@ -7,5 +7,6 @@ grains:
     - doc.o.o
     - education.o.o
     - fontinfo.o.o
+  reboot_safe: unknown
   salt_cluster: opensuse
   virt_cluster: atreju
diff --git a/pillar/id/crtmgr_infra_opensuse_org.sls b/pillar/id/crtmgr_infra_opensuse_org.sls
index d54c3c8..3306c45 100644
--- a/pillar/id/crtmgr_infra_opensuse_org.sls
+++ b/pillar/id/crtmgr_infra_opensuse_org.sls
@@ -5,6 +5,7 @@ grains:
     - crtmgr.o.o
   roles:
     - crtmgr
+  reboot_safe: unknown
   salt_cluster: opensuse
   virt_cluster: atreju
 users:
diff --git a/pillar/id/daffy1_infra_opensuse_org.sls b/pillar/id/daffy1_infra_opensuse_org.sls
index c7802a4..52eb584 100644
--- a/pillar/id/daffy1_infra_opensuse_org.sls
+++ b/pillar/id/daffy1_infra_opensuse_org.sls
@@ -7,5 +7,6 @@ grains:
     - ha
     - login
     - login_master
+  reboot_safe: unknown
   salt_cluster: opensuse
   virt_cluster: atreju
diff --git a/pillar/id/daffy2_infra_opensuse_org.sls b/pillar/id/daffy2_infra_opensuse_org.sls
index 6f1c3fd..149f76a 100644
--- a/pillar/id/daffy2_infra_opensuse_org.sls
+++ b/pillar/id/daffy2_infra_opensuse_org.sls
@@ -7,5 +7,6 @@ grains:
     - ha
     - login
     - login_slave
+  reboot_safe: unknown
   salt_cluster: opensuse
   virt_cluster: atreju
diff --git a/pillar/id/dale_infra_opensuse_org.sls b/pillar/id/dale_infra_opensuse_org.sls
index d5b2a57..b3a4cca 100644
--- a/pillar/id/dale_infra_opensuse_org.sls
+++ b/pillar/id/dale_infra_opensuse_org.sls
@@ -5,5 +5,6 @@ grains:
     - events.o.o
   roles:
     - web_osem
+  reboot_safe: unknown
   salt_cluster: opensuse
   virt_cluster: atreju
diff --git a/pillar/id/duke_infra_opensuse_org.sls b/pillar/id/duke_infra_opensuse_org.sls
index a43a41e..69771bc 100644
--- a/pillar/id/duke_infra_opensuse_org.sls
+++ b/pillar/id/duke_infra_opensuse_org.sls
@@ -3,5 +3,6 @@ grains:
   country: de
   hostusage:
     - future connect.o.o replacement
+  reboot_safe: unknown
   salt_cluster: opensuse
   virt_cluster: atreju
diff --git a/pillar/id/elsa_infra_opensuse_org.sls b/pillar/id/elsa_infra_opensuse_org.sls
index 4716ca4..a9ebf7f 100644
--- a/pillar/id/elsa_infra_opensuse_org.sls
+++ b/pillar/id/elsa_infra_opensuse_org.sls
@@ -11,6 +11,7 @@ grains:
     - proxy
     - proxy_slave
     - ntp
+  reboot_safe: unknown
   salt_cluster: opensuse
   virt_cluster: atreju
   subrole_ntp: ntp3
diff --git a/pillar/id/etherpad_infra_opensuse_org.sls b/pillar/id/etherpad_infra_opensuse_org.sls
index 34fcc07..e95f651 100644
--- a/pillar/id/etherpad_infra_opensuse_org.sls
+++ b/pillar/id/etherpad_infra_opensuse_org.sls
@@ -3,5 +3,6 @@ grains:
   country: de
   hostusage:
     - etherpad.o.o
+  reboot_safe: unknown
   salt_cluster: opensuse
   virt_cluster: atreju
diff --git a/pillar/id/gcc2_infra_opensuse_org.sls b/pillar/id/gcc2_infra_opensuse_org.sls
index a753740..fe07d8c 100644
--- a/pillar/id/gcc2_infra_opensuse_org.sls
+++ b/pillar/id/gcc2_infra_opensuse_org.sls
@@ -5,5 +5,6 @@ grains:
     - future replacement of gcc.o.o / gcc-stats.i.o.o
   roles:
     - web_gcc
+  reboot_safe: unknown
   salt_cluster: opensuse
   virt_cluster: atreju
diff --git a/pillar/id/icc_infra_opensuse_org.sls b/pillar/id/icc_infra_opensuse_org.sls
index d65986c..74d982d 100644
--- a/pillar/id/icc_infra_opensuse_org.sls
+++ b/pillar/id/icc_infra_opensuse_org.sls
@@ -3,6 +3,7 @@ grains:
   country: de
   hostusage:
     - icc.o.o
+  reboot_safe: unknown
   salt_cluster: opensuse
   virt_cluster: atreju
 
diff --git a/pillar/id/keyserver1_infra_opensuse_org.sls b/pillar/id/keyserver1_infra_opensuse_org.sls
index 076fc12..ac8717d 100644
--- a/pillar/id/keyserver1_infra_opensuse_org.sls
+++ b/pillar/id/keyserver1_infra_opensuse_org.sls
@@ -5,5 +5,6 @@ grains:
     - keyserver1.o.o
   roles:
     - web_keyserver
+  reboot_safe: unknown
   salt_cluster: opensuse
   virt_cluster: atreju
diff --git a/pillar/id/kruemel_infra_opensuse_org.sls b/pillar/id/kruemel_infra_opensuse_org.sls
index 020e6fe..8841581 100644
--- a/pillar/id/kruemel_infra_opensuse_org.sls
+++ b/pillar/id/kruemel_infra_opensuse_org.sls
@@ -4,5 +4,6 @@ grains:
   hostusage:
     - planet.o.o
     - rendering of countdown.o.o (rsynced to community.infra.o.o)
+  reboot_safe: unknown
   salt_cluster: opensuse
   virt_cluster: atreju
diff --git a/pillar/id/kubic_infra_opensuse_org.sls b/pillar/id/kubic_infra_opensuse_org.sls
index 2c28339..97952e4 100644
--- a/pillar/id/kubic_infra_opensuse_org.sls
+++ b/pillar/id/kubic_infra_opensuse_org.sls
@@ -3,5 +3,6 @@ grains:
   country: de
   hostusage:
     - kubic.o.o
+  reboot_safe: unknown
   salt_cluster: opensuse
   virt_cluster: atreju
diff --git a/pillar/id/lnt_infra_opensuse_org.sls b/pillar/id/lnt_infra_opensuse_org.sls
index 6a81abc..9549f1c 100644
--- a/pillar/id/lnt_infra_opensuse_org.sls
+++ b/pillar/id/lnt_infra_opensuse_org.sls
@@ -5,5 +5,6 @@ grains:
     - lnt.o.o
   roles:
     - web_lnt
+  reboot_safe: unknown
   salt_cluster: opensuse
   virt_cluster: atreju
diff --git a/pillar/id/metrics_infra_opensuse_org.sls b/pillar/id/metrics_infra_opensuse_org.sls
index 944e52b..5afadb5 100644
--- a/pillar/id/metrics_infra_opensuse_org.sls
+++ b/pillar/id/metrics_infra_opensuse_org.sls
@@ -3,5 +3,6 @@ grains:
   country: de
   hostusage:
     - metrics.o.o
+  reboot_safe: unknown
   salt_cluster: opensuse
   virt_cluster: atreju
diff --git a/pillar/id/mickey_infra_opensuse_org.sls b/pillar/id/mickey_infra_opensuse_org.sls
index 6785e3a..a2e7135 100644
--- a/pillar/id/mickey_infra_opensuse_org.sls
+++ b/pillar/id/mickey_infra_opensuse_org.sls
@@ -5,5 +5,6 @@ grains:
     - gitlab.i.o.o
   roles:
     - web_gitlab
+  reboot_safe: unknown
   salt_cluster: opensuse
   virt_cluster: atreju
diff --git a/pillar/id/minnie_infra_opensuse_org.sls b/pillar/id/minnie_infra_opensuse_org.sls
index 47a9521..3a3b23e 100644
--- a/pillar/id/minnie_infra_opensuse_org.sls
+++ b/pillar/id/minnie_infra_opensuse_org.sls
@@ -5,5 +5,6 @@ grains:
     - saltmaster
   roles:
     - saltmaster
+  reboot_safe: unknown
   salt_cluster: opensuse
   virt_cluster: atreju
diff --git a/pillar/id/monitor_infra_opensuse_org.sls b/pillar/id/monitor_infra_opensuse_org.sls
index 94d35de..885f586 100644
--- a/pillar/id/monitor_infra_opensuse_org.sls
+++ b/pillar/id/monitor_infra_opensuse_org.sls
@@ -9,5 +9,6 @@ grains:
     - ircbot
     - syslog
     - monitoring
+  reboot_safe: unknown
   salt_cluster: opensuse
   virt_cluster: atreju
diff --git a/pillar/id/mufasa_infra_opensuse_org.sls b/pillar/id/mufasa_infra_opensuse_org.sls
index df3430c..f412aaf 100644
--- a/pillar/id/mufasa_infra_opensuse_org.sls
+++ b/pillar/id/mufasa_infra_opensuse_org.sls
@@ -5,5 +5,6 @@ grains:
     - proxy-prv.o.o
   roles:
     - proxy
+  reboot_safe: unknown
   salt_cluster: opensuse
   virt_cluster: bryce
diff --git a/pillar/id/narwal2_infra_opensuse_org.sls b/pillar/id/narwal2_infra_opensuse_org.sls
index c71e073..9ec47e6 100644
--- a/pillar/id/narwal2_infra_opensuse_org.sls
+++ b/pillar/id/narwal2_infra_opensuse_org.sls
@@ -5,5 +5,6 @@ grains:
     - static.o.o
   roles:
     - web_static
+  reboot_safe: unknown
   salt_cluster: opensuse
   virt_cluster: atreju
diff --git a/pillar/id/narwal3_infra_opensuse_org.sls b/pillar/id/narwal3_infra_opensuse_org.sls
index d104da8..f2b0310 100644
--- a/pillar/id/narwal3_infra_opensuse_org.sls
+++ b/pillar/id/narwal3_infra_opensuse_org.sls
@@ -8,5 +8,6 @@ grains:
     - studioexpress.o.o
   roles:
     - web_static
+  reboot_safe: unknown
   salt_cluster: opensuse
   virt_cluster: atreju
diff --git a/pillar/id/narwal5_infra_opensuse_org.sls b/pillar/id/narwal5_infra_opensuse_org.sls
index f3f4d33..32c1dc4 100644
--- a/pillar/id/narwal5_infra_opensuse_org.sls
+++ b/pillar/id/narwal5_infra_opensuse_org.sls
@@ -7,5 +7,6 @@ grains:
   roles:
     - static_master
     - web_static
+  reboot_safe: yes
   salt_cluster: opensuse
   virt_cluster: atreju
diff --git a/pillar/id/narwal6_infra_opensuse_org.sls b/pillar/id/narwal6_infra_opensuse_org.sls
index c71e073..949dd16 100644
--- a/pillar/id/narwal6_infra_opensuse_org.sls
+++ b/pillar/id/narwal6_infra_opensuse_org.sls
@@ -5,5 +5,6 @@ grains:
     - static.o.o
   roles:
     - web_static
+  reboot_safe: yes
   salt_cluster: opensuse
   virt_cluster: atreju
diff --git a/pillar/id/narwal7_infra_opensuse_org.sls b/pillar/id/narwal7_infra_opensuse_org.sls
index c71e073..949dd16 100644
--- a/pillar/id/narwal7_infra_opensuse_org.sls
+++ b/pillar/id/narwal7_infra_opensuse_org.sls
@@ -5,5 +5,6 @@ grains:
     - static.o.o
   roles:
     - web_static
+  reboot_safe: yes
   salt_cluster: opensuse
   virt_cluster: atreju
diff --git a/pillar/id/narwal_infra_opensuse_org.sls b/pillar/id/narwal_infra_opensuse_org.sls
index c71e073..9ec47e6 100644
--- a/pillar/id/narwal_infra_opensuse_org.sls
+++ b/pillar/id/narwal_infra_opensuse_org.sls
@@ -5,5 +5,6 @@ grains:
     - static.o.o
   roles:
     - web_static
+  reboot_safe: unknown
   salt_cluster: opensuse
   virt_cluster: atreju
diff --git a/pillar/id/nuka_infra_opensuse_org.sls b/pillar/id/nuka_infra_opensuse_org.sls
index 2881b59..bcd35f9 100644
--- a/pillar/id/nuka_infra_opensuse_org.sls
+++ b/pillar/id/nuka_infra_opensuse_org.sls
@@ -5,5 +5,6 @@ grains:
     - l10n.o.o
   roles:
     - weblate
+  reboot_safe: unknown
   salt_cluster: opensuse
   virt_cluster: atreju
diff --git a/pillar/id/obsreview_infra_opensuse_org.sls b/pillar/id/obsreview_infra_opensuse_org.sls
index 3a1e1fa..1778ed0 100644
--- a/pillar/id/obsreview_infra_opensuse_org.sls
+++ b/pillar/id/obsreview_infra_opensuse_org.sls
@@ -3,5 +3,6 @@ grains:
   country: de
   hostusage:
     - future OBS related service
+  reboot_safe: unknown
   salt_cluster: opensuse
   virt_cluster: atreju
diff --git a/pillar/id/olaf_infra_opensuse_org.sls b/pillar/id/olaf_infra_opensuse_org.sls
index ad9312e..9459226 100644
--- a/pillar/id/olaf_infra_opensuse_org.sls
+++ b/pillar/id/olaf_infra_opensuse_org.sls
@@ -6,5 +6,6 @@ grains:
     - scanner.o.o
   roles:
     - web_mirrors
+  reboot_safe: unknown
   salt_cluster: opensuse
   virt_cluster: atreju
diff --git a/pillar/id/pontifex2_infra_opensuse_org.sls b/pillar/id/pontifex2_infra_opensuse_org.sls
index 5fca0f0..c11ed0c 100644
--- a/pillar/id/pontifex2_infra_opensuse_org.sls
+++ b/pillar/id/pontifex2_infra_opensuse_org.sls
@@ -5,5 +5,6 @@ grains:
     - download.o.o
   roles:
     - web_download
+  reboot_safe: unknown
   salt_cluster: opensuse
   virt_cluster: atreju
diff --git a/pillar/id/progress_infra_opensuse_org.sls b/pillar/id/progress_infra_opensuse_org.sls
index 9c4e4ec..82453fa 100644
--- a/pillar/id/progress_infra_opensuse_org.sls
+++ b/pillar/id/progress_infra_opensuse_org.sls
@@ -3,5 +3,6 @@ grains:
   country: de
   hostusage:
     - future progress.o.o replacement
+  reboot_safe: unknown
   salt_cluster: opensuse
   virt_cluster: atreju
diff --git a/pillar/id/rafiki_infra_opensuse_org.sls b/pillar/id/rafiki_infra_opensuse_org.sls
index ccb612f..6335130 100644
--- a/pillar/id/rafiki_infra_opensuse_org.sls
+++ b/pillar/id/rafiki_infra_opensuse_org.sls
@@ -5,5 +5,6 @@ grains:
     - future login3.o.o (provo login proxy)
   roles:
     - login
+  reboot_safe: unknown
   salt_cluster: opensuse
   virt_cluster: bryce
diff --git a/pillar/id/redmine_infra_opensuse_org.sls b/pillar/id/redmine_infra_opensuse_org.sls
index 7320858..3f2c283 100644
--- a/pillar/id/redmine_infra_opensuse_org.sls
+++ b/pillar/id/redmine_infra_opensuse_org.sls
@@ -5,5 +5,6 @@ grains:
     - progress.o.o
   roles:
     - web_progress
+  reboot_safe: unknown
   salt_cluster: opensuse
   virt_cluster: atreju
diff --git a/pillar/id/riesling2_infra_opensuse_org.sls b/pillar/id/riesling2_infra_opensuse_org.sls
index 527a228..e57241d 100644
--- a/pillar/id/riesling2_infra_opensuse_org.sls
+++ b/pillar/id/riesling2_infra_opensuse_org.sls
@@ -7,5 +7,6 @@ grains:
     - mysql
     - wiki
     - wiki_readonly
+  reboot_safe: unknown
   salt_cluster: opensuse
   virt_cluster: bryce
diff --git a/pillar/id/riesling_infra_opensuse_org.sls b/pillar/id/riesling_infra_opensuse_org.sls
index 7dbe2d7..f4c71ff 100644
--- a/pillar/id/riesling_infra_opensuse_org.sls
+++ b/pillar/id/riesling_infra_opensuse_org.sls
@@ -5,5 +5,6 @@ grains:
     - en.o.o (all *.o.o wikis)
   roles:
     - wiki
+  reboot_safe: yes
   salt_cluster: opensuse
   virt_cluster: atreju
diff --git a/pillar/id/rpmlint_infra_opensuse_org.sls b/pillar/id/rpmlint_infra_opensuse_org.sls
index 885032f..03ac220 100644
--- a/pillar/id/rpmlint_infra_opensuse_org.sls
+++ b/pillar/id/rpmlint_infra_opensuse_org.sls
@@ -3,5 +3,6 @@ grains:
   country: de
   hostusage:
     - rpmlint.o.o
+  reboot_safe: unknown
   salt_cluster: opensuse
   virt_cluster: atreju
diff --git a/pillar/id/sarabi_infra_opensuse_org.sls b/pillar/id/sarabi_infra_opensuse_org.sls
index 0680839..e05023a 100644
--- a/pillar/id/sarabi_infra_opensuse_org.sls
+++ b/pillar/id/sarabi_infra_opensuse_org.sls
@@ -5,5 +5,6 @@ grains:
     - elections.o.o
   roles:
     - web_elections
+  reboot_safe: yes
   salt_cluster: opensuse
   virt_cluster: atreju
diff --git a/pillar/id/scar_infra_opensuse_org.sls b/pillar/id/scar_infra_opensuse_org.sls
index 1837e0f..5f229c3 100644
--- a/pillar/id/scar_infra_opensuse_org.sls
+++ b/pillar/id/scar_infra_opensuse_org.sls
@@ -5,5 +5,6 @@ grains:
     - gate.o.o
   roles:
     - openvpn
+  reboot_safe: unknown
   salt_cluster: opensuse
   virt_cluster: atreju
diff --git a/pillar/id/simba_infra_opensuse_org.sls b/pillar/id/simba_infra_opensuse_org.sls
index 139fa9b..3e5cd9d 100644
--- a/pillar/id/simba_infra_opensuse_org.sls
+++ b/pillar/id/simba_infra_opensuse_org.sls
@@ -5,5 +5,6 @@ grains:
     - gitlab runner
   roles:
     - worker_gitlab
+  reboot_safe: unknown
   salt_cluster: opensuse
   virt_cluster: atreju
diff --git a/pillar/id/tsp_infra_opensuse_org.sls b/pillar/id/tsp_infra_opensuse_org.sls
index f901d47..c6506e2 100644
--- a/pillar/id/tsp_infra_opensuse_org.sls
+++ b/pillar/id/tsp_infra_opensuse_org.sls
@@ -5,5 +5,6 @@ grains:
     - future travel support program webapp replacement
   roles:
     - web_tsp
+  reboot_safe: unknown
   salt_cluster: opensuse
   virt_cluster: atreju
diff --git a/pillar/id/water2_infra_opensuse_org.sls b/pillar/id/water2_infra_opensuse_org.sls
index d769f48..713a613 100644
--- a/pillar/id/water2_infra_opensuse_org.sls
+++ b/pillar/id/water2_infra_opensuse_org.sls
@@ -5,5 +5,6 @@ grains:
     - en.o.o wiki search backend
   roles:
     - wikisearch
+  reboot_safe: unknown
   salt_cluster: opensuse
   virt_cluster: bryce
diff --git a/pillar/id/water_infra_opensuse_org.sls b/pillar/id/water_infra_opensuse_org.sls
index d1522a8..3837daf 100644
--- a/pillar/id/water_infra_opensuse_org.sls
+++ b/pillar/id/water_infra_opensuse_org.sls
@@ -5,5 +5,6 @@ grains:
     - en.o.o search backend
   roles:
     - wikisearch
+  reboot_safe: yes
   salt_cluster: opensuse
   virt_cluster: atreju
diff --git a/pillar/valid_custom_grains.yaml b/pillar/valid_custom_grains.yaml
index 9633f03..1fe9fa9 100644
--- a/pillar/valid_custom_grains.yaml
+++ b/pillar/valid_custom_grains.yaml
@@ -1,6 +1,10 @@
 ---
 global:
   hostusage: []
+  reboot_safe:
+    - yes
+    - no
+    - unknown
   salt_cluster: opensuse
 localized:
   de: