Added upgrade guard (and override mechanism)

ci/tasks/upgrade.yml

@@ -32,3 +32,4 @@ params:
   BOSH_CLIENT_SECRET:   ((bosh.password))
   KEEP_STATE:           true
   SECRETS_SEED_DATA:    ((secrets_seed_data))
+  FORCE_INCOMPATIBLE_UPGRADE: yes

hooks/check

@@ -2,7 +2,7 @@
 set -ue
 
 #Version check
-version_check 2.8.5 || exit 1 # TODO: Update to 2.8.6 when released
+version_check 2.8.6 || exit 1
 
 # Cloud Config checks
 ok=yes
@@ -45,6 +45,24 @@ if want_feature vsphere; then
   done
 fi
 
+version="$(exodus kit_version)"
+if [[ -n "${version:-}" ]] ; then
+  set +e
+  if ! new_enough "$version" "3.0.0" ; then
+    describe >&2 "" "  #C{[Checking Upgrade from $version]}"
+
+    if ! new_enough "${version}" "2.2.7-rc.0" ; then
+      describe >&2 "    #R{[ERROR]} Please upgrade to at least bosh kit 2.3.0 before upgrading to v3.x.x"
+      if [[ -n "$FORCE_INCOMPATIBLE_UPGRADE" ]] ; then
+        describe >&2 "    #y{[WARN]} Forcing incompatible upgrade due to FORCE_INCOMPATIBLE_UPGRADE being set"
+      else
+        ok=no
+      fi
+    fi
+  fi
+  set -e
+fi
+
 if [[ "$ok" == "yes" ]]; then
   describe "  environment files [#G{OK}]"
 else