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Reintroduce ExitType

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This introduces `ExitType=main|cgroup` for services.
Similar to how `Type` specifies the launch of a service, `ExitType` is
concerned with how systemd determines that a service exited.

- If set to `main` (the current behavior), the service manager will consider
  the unit stopped when the main process exits.

- The `cgroup` exit type is meant for applications whose forking model is not
  known ahead of time and which might not have a specific main process.
  The service will stay running as long as at least one process in the cgroup
  is running. This is intended for transient or automatically generated
  services, such as graphical applications inside of a desktop environment.

Motivation for this is #16805. The original PR (#18782) was reverted (#20073)
after realizing that the exit status of "the last process in the cgroup" can't
reliably be known (#19385)

This version instead uses the main process exit status if there is one and just
listens to the cgroup empty event otherwise.

The advantages of a service with `ExitType=cgroup` over scopes are:
- Integrated logging / stdout redirection
- Avoids the race / synchronisation issue between launch and scope creation
- More extensive use of drop-ins and thus distro-level configuration:
  by moving from scopes to services we can have drop ins that will affect
  properties that can only be set during service creation,
  like `OOMPolicy` and security-related properties
- It makes systemd-xdg-autostart-generator usable by fixing [1], as obviously
  only services can be used in the generator, not scopes.

[1] https://bugs.kde.org/show_bug.cgi?id=433299
This commit is contained in:
Henri Chain 2021-02-24 16:13:21 +01:00
parent 20f7ada699
commit 596e447076
17 changed files with 234 additions and 68 deletions
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1
docs/TRANSIENT-SETTINGS.md
View File

@ -307,6 +307,7 @@ Most service unit settings are available for transient units.
✓ ExecStartPre=
✓ ExecStop=
✓ ExecStopPost=
✓ ExitType=
✓ FileDescriptorStoreMax=
✓ GuessMainPID=
✓ NonBlocking=

6
man/org.freedesktop.systemd1.xml
View File

@ -2304,6 +2304,8 @@ node /org/freedesktop/systemd1/unit/avahi_2ddaemon_2eservice {
@org.freedesktop.DBus.Property.EmitsChangedSignal("const")
readonly s Type = '...';
@org.freedesktop.DBus.Property.EmitsChangedSignal("const")
readonly s ExitType = '...';
@org.freedesktop.DBus.Property.EmitsChangedSignal("const")
readonly s Restart = '...';
@org.freedesktop.DBus.Property.EmitsChangedSignal("const")
readonly s PIDFile = '...';
@ -2894,6 +2896,8 @@ node /org/freedesktop/systemd1/unit/avahi_2ddaemon_2eservice {
<!--property Type is not documented!-->
<!--property ExitType is not documented!-->
<!--property Restart is not documented!-->
<!--property PIDFile is not documented!-->
@ -3420,6 +3424,8 @@ node /org/freedesktop/systemd1/unit/avahi_2ddaemon_2eservice {
<variablelist class="dbus-property" generated="True" extra-ref="Type"/>
<variablelist class="dbus-property" generated="True" extra-ref="ExitType"/>
<variablelist class="dbus-property" generated="True" extra-ref="Restart"/>
<variablelist class="dbus-property" generated="True" extra-ref="PIDFile"/>

25
man/systemd.service.xml
View File

@ -255,6 +255,31 @@
</listitem>
</varlistentry>
<varlistentry>
<term><varname>ExitType=</varname></term>
<listitem>
<para>Specifies when the manager should consider the service to be finished. One of <option>main</option> or
<option>cgroup</option>:</para>
<itemizedlist>
<listitem><para>If set to <option>main</option> (the default), the service manager
will consider the unit stopped when the main process, which is determined according to the
<varname>Type=</varname>, exits. Consequently, it cannot be used with
<varname>Type=</varname><option>oneshot</option>.</para></listitem>
<listitem><para>If set to <option>cgroup</option>, the service will be considered running as long as at
least one process in the cgroup has not exited.</para></listitem>
</itemizedlist>
<para>It is generally recommended to use <varname>ExitType=</varname><option>main</option> when a service has
a known forking model and a main process can reliably be determined. <varname>ExitType=</varname>
<option>cgroup</option> is meant for applications whose forking model is not known ahead of time and which
might not have a specific main process. It is well suited for transient or automatically generated services,
such as graphical applications inside of a desktop environment.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><varname>RemainAfterExit=</varname></term>

2
shell-completion/bash/systemd-run
View File

@ -78,7 +78,7 @@ _systemd_run() {
-p|--property)
local comps='CPUAccounting= MemoryAccounting= BlockIOAccounting= SendSIGHUP=
SendSIGKILL= MemoryLimit= CPUShares= BlockIOWeight= User= Group=
DevicePolicy= KillMode= DeviceAllow= BlockIOReadBandwidth=
DevicePolicy= KillMode= ExitType= DeviceAllow= BlockIOReadBandwidth=
BlockIOWriteBandwidth= BlockIODeviceWeight= Nice= Environment=
KillSignal= RestartKillSignal= FinalKillSignal= LimitCPU= LimitFSIZE= LimitDATA=
LimitSTACK= LimitCORE= LimitRSS= LimitNOFILE= LimitAS= LimitNPROC=

2
shell-completion/zsh/_systemd-run
View File

@ -45,7 +45,7 @@ _arguments \
{-p+,--property=}'[Set unit property]:NAME=VALUE:(( \
CPUAccounting= MemoryAccounting= BlockIOAccounting= SendSIGHUP= \
SendSIGKILL= MemoryLimit= CPUShares= BlockIOWeight= User= Group= \
DevicePolicy= KillMode= DeviceAllow= BlockIOReadBandwidth= \
DevicePolicy= KillMode= ExitType= DeviceAllow= BlockIOReadBandwidth= \
BlockIOWriteBandwidth= BlockIODeviceWeight= Nice= Environment= \
KillSignal= RestartKillSignal= FinalKillSignal= LimitCPU= LimitFSIZE= LimitDATA= \
LimitSTACK= LimitCORE= LimitRSS= LimitNOFILE= LimitAS= LimitNPROC= \

6
src/core/dbus-service.c
View File

@ -27,6 +27,7 @@
#include "unit.h"
static BUS_DEFINE_PROPERTY_GET_ENUM(property_get_type, service_type, ServiceType);
static BUS_DEFINE_PROPERTY_GET_ENUM(property_get_exit_type, service_exit_type, ServiceExitType);
static BUS_DEFINE_PROPERTY_GET_ENUM(property_get_result, service_result, ServiceResult);
static BUS_DEFINE_PROPERTY_GET_ENUM(property_get_restart, service_restart, ServiceRestart);
static BUS_DEFINE_PROPERTY_GET_ENUM(property_get_notify_access, notify_access, NotifyAccess);
@ -192,6 +193,7 @@ int bus_service_method_mount_image(sd_bus_message *message, void *userdata, sd_b
const sd_bus_vtable bus_service_vtable[] = {
SD_BUS_VTABLE_START(0),
SD_BUS_PROPERTY("Type", "s", property_get_type, offsetof(Service, type), SD_BUS_VTABLE_PROPERTY_CONST),
SD_BUS_PROPERTY("ExitType", "s", property_get_exit_type, offsetof(Service, exit_type), SD_BUS_VTABLE_PROPERTY_CONST),
SD_BUS_PROPERTY("Restart", "s", property_get_restart, offsetof(Service, restart), SD_BUS_VTABLE_PROPERTY_CONST),
SD_BUS_PROPERTY("PIDFile", "s", NULL, offsetof(Service, pid_file), SD_BUS_VTABLE_PROPERTY_CONST),
SD_BUS_PROPERTY("NotifyAccess", "s", property_get_notify_access, offsetof(Service, notify_access), SD_BUS_VTABLE_PROPERTY_CONST),
@ -378,6 +380,7 @@ static int bus_set_transient_std_fd(
}
static BUS_DEFINE_SET_TRANSIENT_PARSE(notify_access, NotifyAccess, notify_access_from_string);
static BUS_DEFINE_SET_TRANSIENT_PARSE(service_type, ServiceType, service_type_from_string);
static BUS_DEFINE_SET_TRANSIENT_PARSE(service_exit_type, ServiceExitType, service_exit_type_from_string);
static BUS_DEFINE_SET_TRANSIENT_PARSE(service_restart, ServiceRestart, service_restart_from_string);
static BUS_DEFINE_SET_TRANSIENT_PARSE(oom_policy, OOMPolicy, oom_policy_from_string);
static BUS_DEFINE_SET_TRANSIENT_STRING_WITH_CHECK(bus_name, sd_bus_service_name_is_valid);
@ -415,6 +418,9 @@ static int bus_service_set_transient_property(
if (streq(name, "Type"))
return bus_set_transient_service_type(u, name, &s->type, message, flags, error);
if (streq(name, "ExitType"))
return bus_set_transient_service_exit_type(u, name, &s->exit_type, message, flags, error);
if (streq(name, "OOMPolicy"))
return bus_set_transient_oom_policy(u, name, &s->oom_policy, message, flags, error);

1
src/core/load-fragment-gperf.gperf.in
View File

@ -392,6 +392,7 @@ Service.StartLimitAction, config_parse_emergency_action,
Service.FailureAction, config_parse_emergency_action, 0, offsetof(Unit, failure_action)
Service.RebootArgument, config_parse_unit_string_printf, 0, offsetof(Unit, reboot_arg)
Service.Type, config_parse_service_type, 0, offsetof(Service, type)
Service.ExitType, config_parse_service_exit_type, 0, offsetof(Service, exit_type)
Service.Restart, config_parse_service_restart, 0, offsetof(Service, restart)
Service.PermissionsStartOnly, config_parse_bool, 0, offsetof(Service, permissions_start_only)
Service.RootDirectoryStartOnly, config_parse_bool, 0, offsetof(Service, root_directory_start_only)

2
src/core/load-fragment.c
View File

@ -136,6 +136,7 @@ DEFINE_CONFIG_PARSE_ENUM(config_parse_protect_home, protect_home, ProtectHome, "
DEFINE_CONFIG_PARSE_ENUM(config_parse_protect_system, protect_system, ProtectSystem, "Failed to parse protect system value");
DEFINE_CONFIG_PARSE_ENUM(config_parse_runtime_preserve_mode, exec_preserve_mode, ExecPreserveMode, "Failed to parse runtime directory preserve mode");
DEFINE_CONFIG_PARSE_ENUM(config_parse_service_type, service_type, ServiceType, "Failed to parse service type");
DEFINE_CONFIG_PARSE_ENUM(config_parse_service_exit_type, service_exit_type, ServiceExitType, "Failed to parse service exit type");
DEFINE_CONFIG_PARSE_ENUM(config_parse_service_restart, service_restart, ServiceRestart, "Failed to parse service restart specifier");
DEFINE_CONFIG_PARSE_ENUM(config_parse_service_timeout_failure_mode, service_timeout_failure_mode, ServiceTimeoutFailureMode, "Failed to parse timeout failure mode");
DEFINE_CONFIG_PARSE_ENUM(config_parse_socket_bind, socket_address_bind_ipv6_only_or_bool, SocketAddressBindIPv6Only, "Failed to parse bind IPv6 only value");
@ -6194,6 +6195,7 @@ void unit_dump_config_items(FILE *f) {
{ config_parse_unit_deps, "UNIT [...]" },
{ config_parse_exec, "PATH [ARGUMENT [...]]" },
{ config_parse_service_type, "SERVICETYPE" },
{ config_parse_service_exit_type, "SERVICEEXITTYPE" },
{ config_parse_service_restart, "SERVICERESTART" },
{ config_parse_service_timeout_failure_mode, "TIMEOUTMODE" },
{ config_parse_kill_mode, "KILLMODE" },

1
src/core/load-fragment.h
View File

@ -37,6 +37,7 @@ CONFIG_PARSER_PROTOTYPE(config_parse_service_timeout);
CONFIG_PARSER_PROTOTYPE(config_parse_service_timeout_abort);
CONFIG_PARSER_PROTOTYPE(config_parse_service_timeout_failure_mode);
CONFIG_PARSER_PROTOTYPE(config_parse_service_type);
CONFIG_PARSER_PROTOTYPE(config_parse_service_exit_type);
CONFIG_PARSER_PROTOTYPE(config_parse_service_restart);
CONFIG_PARSER_PROTOTYPE(config_parse_socket_bindtodevice);
CONFIG_PARSER_PROTOTYPE(config_parse_exec_output);

148
src/core/service.c
View File

@ -602,6 +602,9 @@ static int service_verify(Service *s) {
if (s->type == SERVICE_ONESHOT && !exit_status_set_is_empty(&s->restart_force_status))
return log_unit_error_errno(UNIT(s), SYNTHETIC_ERRNO(ENOEXEC), "Service has RestartForceStatus= set, which isn't allowed for Type=oneshot services. Refusing.");
if (s->type == SERVICE_ONESHOT && s->exit_type == SERVICE_EXIT_CGROUP)
return log_unit_error_errno(UNIT(s), SYNTHETIC_ERRNO(ENOEXEC), "Service has ExitType=cgroup set, which isn't allowed for Type=oneshot services. Refusing.");
if (s->type == SERVICE_DBUS && !s->bus_name)
return log_unit_error_errno(UNIT(s), SYNTHETIC_ERRNO(ENOEXEC), "Service is of type D-Bus but no D-Bus service name has been specified. Refusing.");
@ -3289,6 +3292,9 @@ static void service_notify_cgroup_empty_event(Unit *u) {
break;
}
if (s->exit_type == SERVICE_EXIT_CGROUP && main_pid_good(s) <= 0)
service_enter_start_post(s);
_fallthrough_;
case SERVICE_START_POST:
if (s->pid_file_pathspec &&
@ -3477,79 +3483,82 @@ static void service_sigchld_event(Unit *u, pid_t pid, int code, int status) {
service_run_next_main(s);
} else {
/* The service exited, so the service is officially gone. */
s->main_command = NULL;
switch (s->state) {
/* Services with ExitType=cgroup do not act on main PID exiting,
* unless the cgroup is already empty */
if (s->exit_type == SERVICE_EXIT_MAIN || cgroup_good(s) <= 0) {
/* The service exited, so the service is officially gone. */
switch (s->state) {
case SERVICE_START_POST:
case SERVICE_RELOAD:
/* If neither main nor control processes are running then
* the current state can never exit cleanly, hence immediately
* terminate the service. */
if (control_pid_good(s) <= 0)
service_enter_stop(s, f);
case SERVICE_START_POST:
case SERVICE_RELOAD:
/* If neither main nor control processes are running then
* the current state can never exit cleanly, hence immediately
* terminate the service. */
if (control_pid_good(s) <= 0)
service_enter_stop(s, f);
/* Otherwise need to wait until the operation is done. */
break;
case SERVICE_STOP:
/* Need to wait until the operation is done. */
break;
case SERVICE_START:
if (s->type == SERVICE_ONESHOT) {
/* This was our main goal, so let's go on */
if (f == SERVICE_SUCCESS)
service_enter_start_post(s);
else
service_enter_signal(s, SERVICE_STOP_SIGTERM, f);
/* Otherwise need to wait until the operation is done. */
break;
} else if (s->type == SERVICE_NOTIFY) {
/* Only enter running through a notification, so that the
* SERVICE_START state signifies that no ready notification
* has been received */
if (f != SERVICE_SUCCESS)
service_enter_signal(s, SERVICE_STOP_SIGTERM, f);
else if (!s->remain_after_exit || s->notify_access == NOTIFY_MAIN)
/* The service has never been and will never be active */
service_enter_signal(s, SERVICE_STOP_SIGTERM, SERVICE_FAILURE_PROTOCOL);
case SERVICE_STOP:
/* Need to wait until the operation is done. */
break;
case SERVICE_START:
if (s->type == SERVICE_ONESHOT) {
/* This was our main goal, so let's go on */
if (f == SERVICE_SUCCESS)
service_enter_start_post(s);
else
service_enter_signal(s, SERVICE_STOP_SIGTERM, f);
break;
} else if (s->type == SERVICE_NOTIFY) {
/* Only enter running through a notification, so that the
* SERVICE_START state signifies that no ready notification
* has been received */
if (f != SERVICE_SUCCESS)
service_enter_signal(s, SERVICE_STOP_SIGTERM, f);
else if (!s->remain_after_exit || s->notify_access == NOTIFY_MAIN)
/* The service has never been and will never be active */
service_enter_signal(s, SERVICE_STOP_SIGTERM, SERVICE_FAILURE_PROTOCOL);
break;
}
_fallthrough_;
case SERVICE_RUNNING:
service_enter_running(s, f);
break;
case SERVICE_STOP_WATCHDOG:
case SERVICE_STOP_SIGTERM:
case SERVICE_STOP_SIGKILL:
if (control_pid_good(s) <= 0)
service_enter_stop_post(s, f);
/* If there is still a control process, wait for that first */
break;
case SERVICE_STOP_POST:
if (control_pid_good(s) <= 0)
service_enter_signal(s, SERVICE_FINAL_SIGTERM, f);
break;
case SERVICE_FINAL_WATCHDOG:
case SERVICE_FINAL_SIGTERM:
case SERVICE_FINAL_SIGKILL:
if (control_pid_good(s) <= 0)
service_enter_dead(s, f, true);
break;
default:
assert_not_reached();
}
_fallthrough_;
case SERVICE_RUNNING:
service_enter_running(s, f);
break;
case SERVICE_STOP_WATCHDOG:
case SERVICE_STOP_SIGTERM:
case SERVICE_STOP_SIGKILL:
if (control_pid_good(s) <= 0)
service_enter_stop_post(s, f);
/* If there is still a control process, wait for that first */
break;
case SERVICE_STOP_POST:
if (control_pid_good(s) <= 0)
service_enter_signal(s, SERVICE_FINAL_SIGTERM, f);
break;
case SERVICE_FINAL_WATCHDOG:
case SERVICE_FINAL_SIGTERM:
case SERVICE_FINAL_SIGKILL:
if (control_pid_good(s) <= 0)
service_enter_dead(s, f, true);
break;
default:
assert_not_reached();
}
}
@ -4513,6 +4522,13 @@ static const char* const service_type_table[_SERVICE_TYPE_MAX] = {
DEFINE_STRING_TABLE_LOOKUP(service_type, ServiceType);
static const char* const service_exit_type_table[_SERVICE_EXIT_TYPE_MAX] = {
[SERVICE_EXIT_MAIN] = "main",
[SERVICE_EXIT_CGROUP] = "cgroup",
};
DEFINE_STRING_TABLE_LOOKUP(service_exit_type, ServiceExitType);
static const char* const service_exec_command_table[_SERVICE_EXEC_COMMAND_MAX] = {
[SERVICE_EXEC_CONDITION] = "ExecCondition",
[SERVICE_EXEC_START_PRE] = "ExecStartPre",

11
src/core/service.h
View File

@ -35,6 +35,13 @@ typedef enum ServiceType {
_SERVICE_TYPE_INVALID = -EINVAL,
} ServiceType;
typedef enum ServiceExitType {
SERVICE_EXIT_MAIN, /* we consider the main PID when deciding if the service exited */
SERVICE_EXIT_CGROUP, /* we wait for the last process in the cgroup to exit */
_SERVICE_EXIT_TYPE_MAX,
_SERVICE_EXIT_TYPE_INVALID = -EINVAL,
} ServiceExitType;
typedef enum ServiceExecCommand {
SERVICE_EXEC_CONDITION,
SERVICE_EXEC_START_PRE,
@ -97,6 +104,7 @@ struct Service {
Unit meta;
ServiceType type;
ServiceExitType exit_type;
ServiceRestart restart;
ExitStatusSet restart_prevent_status;
ExitStatusSet restart_force_status;
@ -227,6 +235,9 @@ ServiceRestart service_restart_from_string(const char *s) _pure_;
const char* service_type_to_string(ServiceType i) _const_;
ServiceType service_type_from_string(const char *s) _pure_;
const char* service_exit_type_to_string(ServiceExitType i) _const_;
ServiceExitType service_exit_type_from_string(const char *s) _pure_;
const char* service_exec_command_to_string(ServiceExecCommand i) _const_;
ServiceExecCommand service_exec_command_from_string(const char *s) _pure_;

1
src/shared/bus-unit-util.c
View File

@ -2130,6 +2130,7 @@ static int bus_append_service_property(sd_bus_message *m, const char *field, con
if (STR_IN_SET(field, "PIDFile",
"Type",
"ExitType",
"Restart",
"BusName",
"NotifyAccess",

1
test/TEST-56-EXIT-TYPE/Makefile Symbolic link
View File

@ -0,0 +1 @@
../TEST-01-BASIC/Makefile

9
test/TEST-56-EXIT-TYPE/test.sh Executable file
View File

@ -0,0 +1,9 @@
#!/usr/bin/env bash
set -e
TEST_DESCRIPTION="test ExitType=cgroup"
# shellcheck source=test/test-functions
. "${TEST_BASE_DIR:?}/test-functions"
do_test "$@"

1
test/fuzz/fuzz-unit-file/directives.service
View File

@ -161,6 +161,7 @@ ExecStartPost=
ExecStartPre=
ExecStop=
ExecStopPost=
ExitType=
ExtensionImages=
FailureAction=
FileDescriptorStoreMax=

6
test/units/testsuite-56.service Normal file
View File

@ -0,0 +1,6 @@
[Unit]
Description=TEST-56-EXIT-TYPE
[Service]
ExecStart=/usr/lib/systemd/tests/testdata/units/%N.sh
Type=oneshot

79
test/units/testsuite-56.sh Executable file
View File

@ -0,0 +1,79 @@
#!/usr/bin/env bash
set -eux
systemd-analyze log-level debug
# Multiple level process tree, parent process stays up
cat >/tmp/test56-exit-cgroup.sh <<EOF
#!/usr/bin/env bash
set -eux
# process tree: systemd -> sleep
sleep infinity &
disown
# process tree: systemd -> bash -> bash -> sleep
((sleep infinity); true) &
systemd-notify --ready
# process tree: systemd -> bash -> sleep
sleep infinity
EOF
chmod +x /tmp/test56-exit-cgroup.sh
# service should be stopped cleanly
systemd-run --wait --unit=one -p Type=notify -p ExitType=cgroup \
-p ExecStartPost='bash -c "systemctl stop one &"' \
/tmp/test56-exit-cgroup.sh
# same thing with a truthy exec condition
systemd-run --wait --unit=two -p Type=notify -p ExitType=cgroup \
-p ExecCondition=true \
-p ExecStartPost='bash -c "systemctl stop two &"' \
/tmp/test56-exit-cgroup.sh
# false exec condition: systemd-run should exit immediately with status code: 1
systemd-run --wait --unit=three -p Type=notify -p ExitType=cgroup \
-p ExecCondition=false \
/tmp/test56-exit-cgroup.sh \
&& { echo 'unexpected success'; exit 1; }
# service should exit uncleanly (main process exits with SIGKILL)
systemd-run --wait --unit=four -p Type=notify -p ExitType=cgroup \
-p ExecStartPost='bash -c "systemctl kill --signal 9 four &"' \
/tmp/test56-exit-cgroup.sh \
&& { echo 'unexpected success'; exit 1; }
# Multiple level process tree, parent process exits quickly
cat >/tmp/test56-exit-cgroup-parentless.sh <<EOF
#!/usr/bin/env bash
set -eux
# process tree: systemd -> sleep
sleep infinity &
# process tree: systemd -> bash -> sleep
((sleep infinity); true) &
systemd-notify --ready
EOF
chmod +x /tmp/test56-exit-cgroup-parentless.sh
# service should be stopped cleanly
systemd-run --wait --unit=five -p Type=notify -p ExitType=cgroup \
-p ExecStartPost='bash -c "systemctl stop five &"' \
/tmp/test56-exit-cgroup-parentless.sh
# service should still exit cleanly despite SIGKILL (the main process already exited cleanly)
systemd-run --wait --unit=six -p Type=notify -p ExitType=cgroup \
-p ExecStartPost='bash -c "systemctl kill --signal 9 six &"' \
/tmp/test56-exit-cgroup-parentless.sh
systemd-analyze log-level info
echo OK >/testok
exit 0