systemd: added new dependency PartOf

This should address TODO item "new dependency type to "group" services
in a target". Semantic of new dependency is as follows. Once configured
it creates dependency which will cause that all dependent units get
stopped if unit they all depend on is stopped or restarted.  Usual use
case would be configuring PartOf=some.target in template unit file
and WantedBy=some.target in [Install] section and enabling desired
number of instances. In this case starting one instance won't pull in
target but stopping or starting target(in case of WantedBy is properly
configured) will cause stop/start of all instances.

5 files changed, 32 insertions, 1 deletions

diff --git a/man/systemd.unit.xml b/man/systemd.unit.xml
index 286862006a..bdd8f7d701 100644
--- a/man/systemd.unit.xml
+++ b/man/systemd.unit.xml
@@ -442,6 +442,21 @@
                         </varlistentry>
 
                         <varlistentry>
+                                <term><varname>PartOf=</varname></term>
+
+                                 <listitem><para>Configures dependency
+                                 on other unit. When systemd stops or
+                                 restarts unit listed here, stop or
+                                 restart is propagated to dependent
+                                 units. Note that this is one way
+                                 dependency and changes to dependent
+                                 units does not affect listed unit. If
+                                 something else is desired, please
+                                 use some other type of dependency.
+                                 </para></listitem>
+                        </varlistentry>
+
+                        <varlistentry>
                                 <term><varname>Conflicts=</varname></term>
 
                                 <listitem><para>Configures negative
diff --git a/src/core/load-fragment-gperf.gperf.m4 b/src/core/load-fragment-gperf.gperf.m4
index d6a4711a32..2b1cfa073c 100644
--- a/src/core/load-fragment-gperf.gperf.m4
+++ b/src/core/load-fragment-gperf.gperf.m4
@@ -112,6 +112,7 @@ Unit.PropagatesReloadTo,         config_parse_unit_deps,             UNIT_PROPAG
 Unit.PropagateReloadTo,          config_parse_unit_deps,             UNIT_PROPAGATES_RELOAD_TO,     0
 Unit.ReloadPropagatedFrom,       config_parse_unit_deps,             UNIT_RELOAD_PROPAGATED_FROM,   0
 Unit.PropagateReloadFrom,        config_parse_unit_deps,             UNIT_RELOAD_PROPAGATED_FROM,   0
+Unit.PartOf,                     config_parse_unit_deps,             UNIT_PART_OF,                  0
 Unit.RequiresMountsFor,          config_parse_unit_requires_mounts_for, 0,                          offsetof(Unit, requires_mounts_for)
 Unit.StopWhenUnneeded,           config_parse_bool,                  0,                             offsetof(Unit, stop_when_unneeded)
 Unit.RefuseManualStart,          config_parse_bool,                  0,                             offsetof(Unit, refuse_manual_start)
diff --git a/src/core/transaction.c b/src/core/transaction.c
index a1cf706934..1f8d803aeb 100644
--- a/src/core/transaction.c
+++ b/src/core/transaction.c
@@ -994,6 +994,18 @@ int transaction_add_job_and_dependencies(
                                                 dbus_error_free(e);
                                 }
                         }
+
+                        SET_FOREACH(dep, ret->unit->dependencies[UNIT_CONSISTS_OF], i) {
+                                r = transaction_add_job_and_dependencies(tr, type, dep, ret, true, override, false, false, ignore_order, e);
+                                if (r < 0) {
+                                        if (r != -EBADR)
+                                                goto fail;
+
+                                        if (e)
+                                                dbus_error_free(e);
+                                }
+                        }
+
                 }
 
                 if (type == JOB_RELOAD) {
diff --git a/src/core/unit.c b/src/core/unit.c
index 7b2f597589..be75cd792d 100644
--- a/src/core/unit.c
+++ b/src/core/unit.c
@@ -1610,7 +1610,8 @@ int unit_add_dependency(Unit *u, UnitDependency d, Unit *other, bool add_referen
                 [UNIT_TRIGGERS] = UNIT_TRIGGERED_BY,
                 [UNIT_TRIGGERED_BY] = UNIT_TRIGGERS,
                 [UNIT_PROPAGATES_RELOAD_TO] = UNIT_RELOAD_PROPAGATED_FROM,
-                [UNIT_RELOAD_PROPAGATED_FROM] = UNIT_PROPAGATES_RELOAD_TO
+                [UNIT_RELOAD_PROPAGATED_FROM] = UNIT_PROPAGATES_RELOAD_TO,
+                [UNIT_PART_OF] = UNIT_CONSISTS_OF
         };
         int r, q = 0, v = 0, w = 0;
 
diff --git a/src/core/unit.h b/src/core/unit.h
index 2102b7a570..89bd61c2d8 100644
--- a/src/core/unit.h
+++ b/src/core/unit.h
@@ -75,12 +75,14 @@ enum UnitDependency {
         UNIT_REQUISITE_OVERRIDABLE,
         UNIT_WANTS,
         UNIT_BINDS_TO,
+        UNIT_PART_OF,
 
         /* Inverse of the above */
         UNIT_REQUIRED_BY,             /* inverse of 'requires' and 'requisite' is 'required_by' */
         UNIT_REQUIRED_BY_OVERRIDABLE, /* inverse of 'requires_overridable' and 'requisite_overridable' is 'soft_required_by' */
         UNIT_WANTED_BY,               /* inverse of 'wants' */
         UNIT_BOUND_BY,                /* inverse of 'binds_to' */
+        UNIT_CONSISTS_OF,             /* inverse of 'part_of' */
 
         /* Negative dependencies */
         UNIT_CONFLICTS,               /* inverse of 'conflicts' is 'conflicted_by' */