skeleton: add systemd network.service unit

Add and enable a systemd unit file to bring up / down network with ifup / ifdown, analogous to the skeleton/etc/init.d/S40network init script.

Signed-off-by Ivan Sergeev <[email protected]>

---
 .../system/multi-user.target.wants/network.service  |  1 +
 system/skeleton/etc/systemd/system/network.service  | 21 +++++++++++++++++++++
 2 files changed, 22 insertions(+)
 create mode 120000 system/skeleton/etc/systemd/system/multi-user.target.wants/network.service
 create mode 100644 system/skeleton/etc/systemd/system/network.service

Dear Ivan Sergeev,

Quoted 7 lines · Ivan Sergeev

Add and enable a systemd unit file to bring up / down network with ifup / ifdown, analogous to the skeleton/etc/init.d/S40network init script.

Signed-off-by Ivan Sergeev <[email protected]>

---
 .../system/multi-user.target.wants/network.service  |  1 +
 system/skeleton/etc/systemd/system/network.service  | 21

+++++++++++++++++++++

Quoted 2 lines

 2 files changed, 22 insertions(+)
 create mode 120000

system/skeleton/etc/systemd/system/multi-user.target.wants/network.service

Quoted 1 line

 create mode 100644 system/skeleton/etc/systemd/system/network.service

We probably want to make that conditional on the type of init system that is used, no?

Thomas
--
Thomas Petazzoni, CTO, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com

Add and enable a systemd unit file to bring up or down network with ifup / ifdown, analogous to the skeleton/etc/init.d/S40network init script.

Signed-off-by Ivan Sergeev <[email protected]>

---
 package/systemd/network.service | 21 +++++++++++++++++++++
 package/systemd/systemd.mk      |  9 +++++++++
 2 files changed, 30 insertions(+)
 create mode 100644 package/systemd/network.service

package/systemd/network.service new file +21 -0

new file mode 100644
index 0000000..0d77bb8
@@ -0,0 +1,21 @@
+[Unit]
+Description=Network Connectivity
+Wants=network.target
+Before=network.target
+
+[Service]
+Type=oneshot
+RemainAfterExit=yes
+
+# lo is brought up earlier, which will cause the upcoming "ifup -a" to fail
+# with exit code 1, due to an "ip: RTNETLINK answers: File exists" error during
+# its "ip addr add ..." command, subsequently causing this unit to fail even
+# though it is a benign error. Flushing the lo address with the command below
+# before ifup prevents this failure.
+ExecStart=/sbin/ip addr flush dev lo
+
+ExecStart=/sbin/ifup -a
+ExecStop=/sbin/ifdown -a
+
+[Install]
+WantedBy=multi-user.target

package/systemd/systemd.mk +9 -0

index a5dc8e5..a99c0da 100644
@@ -72,7 +72,16 @@ define SYSTEMD_INSTALL_TTY_HOOK
 	ln -fs ../../../../usr/lib/systemd/system/serial-getty at .service $(TARGET_DIR)/etc/systemd/system/getty.target.wants/serial-getty@$(BR2_TARGET_GENERIC_GETTY_PORT).service
 endef
 
+define SYSTEMD_INSTALL_NETWORK_HOOK
+	$(INSTALL) -D -m 644 package/systemd/network.service \
+		$(TARGET_DIR)/etc/systemd/system/network.service
+	mkdir -p $(TARGET_DIR)/etc/systemd/system/multi-user.target.wants
+	ln -fs ../network.service \
+		$(TARGET_DIR)/etc/systemd/system/multi-user.target.wants/network.service
+endef
+
 SYSTEMD_POST_INSTALL_TARGET_HOOKS += \
 	SYSTEMD_INSTALL_TTY_HOOK \
+	SYSTEMD_INSTALL_NETWORK_HOOK
 
 $(eval $(autotools-package))

Eric,

As our systemd person, could you have a look at this patch, and give your comments and/or Acked-by/Reviewed-by as appropriate?

I've tested the patch. It is OK, but I made some modifications:

- rebase
- the new network.service is not installed if systemd-networkd is selected, as they conflict.

The updated version can be found at http://patchwork.ozlabs.org/patch/359561/.

Currently, it seems that the /etc/init.d scripts are copied over blindly from the target skeleton to the target even if systemd (and not busybox) is the chosen init system. Moving forward, having both busybox and systemd init files in the skeleton, like this patch would have, will always clutter /etc/ with some unused init files in the target system, since only one init system will be active.

Should such init files be conditional targets in system/system.mk ? Or should S40network be owned and copied over by package/busybox, and network.service be owned and copied over by package/systemd, instead of having them included statically in the target skeleton?

Quoted 8 lines · Ivan Sergeev

Currently, it seems that the /etc/init.d scripts are copied over blindly from the target skeleton to the target even if systemd (and not busybox) is the chosen init system. Moving forward, having both busybox and systemd init files in the skeleton, like this patch would have, will always clutter /etc/ with some unused init files in the target system, since only one init system will be active.

Quoted 5 lines

Should such init files be conditional targets in system/system.mk ? Or should S40network be owned and copied over by package/busybox, and network.service be owned and copied over by package/systemd, instead of having them included statically in the target skeleton?

I completely agree that the way it is done now is far from ideal.

I think the best way to work with this would be to:

- remove the contents of the init.d directory from the skeleton;

- create a new skeleton fragment system/skeleton-init-sysv that contains etc/init.d;

- create a new skeleton fragment system/skeleton-init-systemd that contains whatever support files are needed by systemd (currently nothing, but your patch would add the networking unit file);

- copy the correct skeleton fragment as part of the .root target, but only if the default skeleton was selected - with a custom skeleton, it's up to the user to provide the right systemd/init.d;

Regards,
Arnout

--

Arnout Vandecappelle                          arnout at mind be
Senior Embedded Software Architect            +32-16-286500
Essensium/Mind                                http://www.mind.be
G.Geenslaan 9, 3001 Leuven, Belgium           BE 872 984 063 RPR Leuven
LinkedIn profile: http://www.linkedin.com/in/arnoutvandecappelle
GPG fingerprint:  7CB5 E4CC 6C2E EFD4 6E3D A754 F963 ECAB 2450 2F1F

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Hi all

Quoted 9 lines · Arnout Vandecappelle

Quoted 8 lines · Ivan Sergeev

Currently, it seems that the /etc/init.d scripts are copied over blindly from the target skeleton to the target even if systemd (and not busybox) is the chosen init system. Moving forward, having both busybox and systemd init files in the skeleton, like this patch would have, will always clutter /etc/ with some unused init files in the target system, since only one init system will be active.

Quoted 4 lines

Quoted 4 lines

Should such init files be conditional targets in system/system.mk ? Or should S40network be owned and copied over by package/busybox, and network.service be owned and copied over by package/systemd, instead of having them included statically in the

target

Quoted 5 lines

Quoted 1 line

skeleton?

I completely agree that the way it is done now is far from ideal.

Quoted 8 lines

I think the best way to work with this would be to:

- remove the contents of the init.d directory from the skeleton;

- create a new skeleton fragment system/skeleton-init-sysv that contains etc/init.d;

- create a new skeleton fragment system/skeleton-init-systemd that

contains

Quoted 4 lines

whatever support files are needed by systemd (currently nothing, but your patch would add the networking unit file);

- copy the correct skeleton fragment as part of the .root target, but

only

Quoted 2 lines

if the default skeleton was selected - with a custom skeleton, it's up to the user to provide the right systemd/init.d;

I agree with you and as a matter of fact, I had already started working on a patch that implement exactly this.

I would even like to go even further, as I have noticed that a lot of the defined LIBFOO_INSTALL_INIT_SYSTEMD and LIBFOO_INSTALL_INIT_SYSV almost always do the exact same stuff.
I would like for the infrastructure to take care of this, if no function is defined, and a .service or S\d{0,2}*, then we should take it and install it.

In that case, any particular requirements, the package define a function, other than that, it's taken care of and we avoid duplicate code in all the packages.

Quoted 19 lines

Regards,
Arnout

--

Arnout Vandecappelle                          arnout at mind be
Senior Embedded Software Architect            +32-16-286500
Essensium/Mind                                http://www.mind.be
G.Geenslaan 9, 3001 Leuven, Belgium           BE 872 984 063 RPR Leuven
LinkedIn profile: http://www.linkedin.com/in/arnoutvandecappelle
GPG fingerprint:  7CB5 E4CC 6C2E EFD4 6E3D A754 F963 ECAB 2450 2F1F

_______________________________________________
buildroot mailing list
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http://lists.busybox.net/mailman/listinfo/buildroot

I would even like to go even further, as I have noticed that a lot of the defined LIBFOO_INSTALL_INIT_SYSTEMD and LIBFOO_INSTALL_INIT_SYSV almost always do the exact same stuff.
I would like for the infrastructure to take care of this, if no function is defined, and a .service or S\d{0,2}*, then we should take it and install it.

In that case, any particular requirements, the package define a function, other than that, it's taken care of and we avoid duplicate code in all the packages.

Quoted 10 lines · Maxime Hadjinlian

I would even like to go even further, as I have noticed that a lot of the defined LIBFOO_INSTALL_INIT_SYSTEMD and LIBFOO_INSTALL_INIT_SYSV almost always do the exact same stuff.
I would like for the infrastructure to take care of this, if no function is defined, and a .service or S\d{0,2}*, then we should take it and install it.

In that case, any particular requirements, the package define a function, other than that, it's taken care of and we avoid duplicate code in all the packages.

Actually, there's two main issues that prevents this in the systemd case, and are why we did it that way:
- the multi-user-wants thing is actually comparable to the sysvinit runlevels. Some packages might want to set their units to other targets than multi-user (for example, graphical applications are likely to go in the graphical target, not the multi-user one)

- Some units also takes "variables" from the created link names. For example, when you want to run getty, you just have a single getty unit, and the device to run getty on is set in the link name to that unit (so you'd end up with a link in multi-user.target.wants that will be getty.ttyS0.service, linking to /etc/systemd/system/getty.service).

At the time, we thought that in the systemd case, the easiest would be to simply write down the 2-3 commands we need to setup the unit, instead of having to give a whole bunch of variables. And we did the same for sysvinit scripts, for consistency.

Maxime

Quoted 12 lines · Maxime Ripard

Quoted 10 lines · Maxime Hadjinlian

I would even like to go even further, as I have noticed that a lot of the defined LIBFOO_INSTALL_INIT_SYSTEMD and LIBFOO_INSTALL_INIT_SYSV almost always do the exact same stuff.
I would like for the infrastructure to take care of this, if no function is defined, and a .service or S\d{0,2}*, then we should take it and install it.

In that case, any particular requirements, the package define a function, other than that, it's taken care of and we avoid duplicate code in all the packages.

Quoted 6 lines

Actually, there's two main issues that prevents this in the systemd case, and are why we did it that way:
- the multi-user-wants thing is actually comparable to the sysvinit runlevels. Some packages might want to set their units to other targets than multi-user (for example, graphical applications are likely to go in the graphical target, not the multi-user one)

I disagree with this one. Buildroot's defaults should support only
a single runlevel/target. That's how it's done for sysv init, and

I'm very happy with it: it's dead easy to see which scripts will be executed at startup, you don't have to find out the runlevel etc. With systemd, things can become even more complex (because there can be several "targets" active at the same time IIRC), and I'd prefer to exclude this complexity by default.

If a user requires several runlevels/targets, than most likely any
default that buildroot provide will not fit anyway, so the user will have to manipulate things in their rootfs overlay or post-build script anyway. Therefore, I think it is better for the user if the defaults are simple and predictable.

Quoted 6 lines

- Some units also takes "variables" from the created link names. For example, when you want to run getty, you just have a single getty unit, and the device to run getty on is set in the link name to that unit (so you'd end up with a link in multi-user.target.wants that will be getty.ttyS0.service, linking to /etc/systemd/system/getty.service).

That is one of the special cases that would be handled in a
post-install hook. But specifically for the getty case, it's not even necessary because we start only a single getty in the default setup, so we can directly install it to getty at ttyS0.service .

Quoted 4 lines

At the time, we thought that in the systemd case, the easiest would be to simply write down the 2-3 commands we need to setup the unit, instead of having to give a whole bunch of variables. And we did the same for sysvinit scripts, for consistency.

I think at the time, we mainly thought that we didn't know yet if
the installation could be generalized. Now that we have a few packages that install unit files, it's more clear that they always to the same.

Also, as far as I understand, the idea is not to add variables, but
rather to check for the existence of package/foo/*.service and install that.

Quoted 20 lines · Arnout Vandecappelle

Quoted 12 lines · Maxime Ripard

Quoted 10 lines · Maxime Hadjinlian

I would even like to go even further, as I have noticed that a lot of the defined LIBFOO_INSTALL_INIT_SYSTEMD and LIBFOO_INSTALL_INIT_SYSV almost always do the exact same stuff.
I would like for the infrastructure to take care of this, if no function is defined, and a .service or S\d{0,2}*, then we should take it and install it.

In that case, any particular requirements, the package define a function, other than that, it's taken care of and we avoid duplicate code in all the packages.

Quoted 6 lines

Actually, there's two main issues that prevents this in the systemd case, and are why we did it that way:
- the multi-user-wants thing is actually comparable to the sysvinit runlevels. Some packages might want to set their units to other targets than multi-user (for example, graphical applications are likely to go in the graphical target, not the multi-user one)

Quoted 2 lines

I disagree with this one. Buildroot's defaults should support only
a single runlevel/target. That's how it's done for sysv init, and

Hmm, afaik, it's not done at all in the sysvinit case, because the default sysvinit we use most of the time (busybox's) doesn't handle the runlevel at all. It's not really the same story there.

Quoted 20 lines

I'm very happy with it: it's dead easy to see which scripts will be executed at startup, you don't have to find out the runlevel etc. With systemd, things can become even more complex (because there can be several "targets" active at the same time IIRC), and I'd prefer to exclude this complexity by default.

If a user requires several runlevels/targets, than most likely any
default that buildroot provide will not fit anyway, so the user will have to manipulate things in their rootfs overlay or post-build script anyway. Therefore, I think it is better for the user if the defaults are simple and predictable.

Quoted 6 lines

- Some units also takes "variables" from the created link names. For example, when you want to run getty, you just have a single getty unit, and the device to run getty on is set in the link name to that unit (so you'd end up with a link in multi-user.target.wants that will be getty.ttyS0.service, linking to /etc/systemd/system/getty.service).

Quoted 4 lines

That is one of the special cases that would be handled in a
post-install hook. But specifically for the getty case, it's not even necessary because we start only a single getty in the default setup, so we can directly install it to getty at ttyS0.service .

Which won't work if you don't have a different tty to export a shell on, but yes, I get your point.

Quoted 5 lines

Quoted 4 lines

At the time, we thought that in the systemd case, the easiest would be to simply write down the 2-3 commands we need to setup the unit, instead of having to give a whole bunch of variables. And we did the same for sysvinit scripts, for consistency.

Quoted 4 lines

I think at the time, we mainly thought that we didn't know yet if
the installation could be generalized. Now that we have a few packages that install unit files, it's more clear that they always to the same.

We have *three* packages with systemd units in current master. I hardly see how you can generalize something out of 3 (similar) samples.

Quoted 4 lines

Also, as far as I understand, the idea is not to add variables, but
rather to check for the existence of package/foo/*.service and install that.

This also doesn't cover the case anymore where a package would ship together with the source code a systemd unit file. I expect it to be more and more common, and it's something that we will want to use most of the time, and not duplicate the unit file in the buildroot package itself.

Maxime

--
Maxime Ripard, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com

Quoted 1 line

Quoted 1 line

Quoted 1 line

Quoted 1 line

"Maxime" == Maxime Ripard <[email protected]> writes:

Quoted 3 lines

Also, as far as I understand, the idea is not to add variables, but rather to check for the existence of package/foo/*.service and install that.

This also doesn't cover the case anymore where a package would ship together with the source code a systemd unit file. I expect it to be more and more common, and it's something that we will want to use most of the time, and not duplicate the unit file in the buildroot package itself.