[OE-core] [meta-oe][poky][PATCH v2] systemd: resolved linked even if the option is disabled
ChenQi
Qi.Chen at windriver.com
Wed Jul 18 03:14:52 UTC 2018
Hi Nicola,
I'd like to detail the current handling of resolv.conf below.
This is the current resolv.conf handling logic.
But if you think there's something wrong about the logic, let me know.
/etc/resolv.conf would be created/written by multiple applications. In
fact, any network manager is likely to handle it.
Our goal is to 1) make sure /etc/resolv.conf always exists and 2) avoid
conflicts among multiple application
In systemd, if 'resolved' is enabled, both '/run/systemd/resolve'
directory and '/run/systemd/resolve/resolv.conf' file will be created by
systemd-resolved. What we need is just to create a symlink to
/run/systemd/resolve/resolv.conf.
That's why we have: ln -s ../run/systemd/resolve/resolv.conf
${D}${sysconfdir}/resolv-conf.systemd
So why /etc/resolv-conf.systemd instead of just /etc/resolv.conf? The
answer is to avoid conflicts with other network managers.
If 'resolved' is not enabled, we still need to ensure the existence of
/etc/resolv.conf. As it has been handled by the 'resolv-conf'
ALTERNATIVE to point to /etc/resov-conf.systemd, we just need to ensure
/etc/resolv-conf.systemd is not a dead link. That why we write 'd
/run/systemd/resolve 0755 root root -' and 'f
/run/systemd/resolve/resolv.conf 0644 root root'. That is to satisfy
goal 1. If we have dropped goal 1, then such operation is not necessary.
But I doubt there would be some problem if we don't satisfy goal 1.
Back to the code block in systemd recipe.
if ! ${@bb.utils.contains('PACKAGECONFIG', 'resolved', 'true',
'false', d)}; then
echo 'L! ${sysconfdir}/resolv.conf - - - -
../run/systemd/resolve/resolv.conf'
>>${D}${exec_prefix}/lib/tmpfiles.d/etc.conf
echo 'd /run/systemd/resolve 0755 root root -'
>>${D}${exec_prefix}/lib/tmpfiles.d/systemd.conf
echo 'f /run/systemd/resolve/resolv.conf 0644 root
root' >>${D}${exec_prefix}/lib/tmpfiles.d/systemd.conf
ln -s ../run/systemd/resolve/resolv.conf
${D}${sysconfdir}/resolv-conf.systemd
else
sed -i -e "s%^L! /etc/resolv.conf.*$%L!
/etc/resolv.conf - - - - ../run/systemd/resolve/resolv.conf%g"
${D}${exec_prefix}/lib/tmpfiles.d/etc.conf
ln -s ../run/systemd/resolve/resolv.conf
${D}${sysconfdir}/resolv-conf.systemd
fi
As we are using 'L' instead of 'L+', you can simply ignore the two
lines, they are more likely to serve as fallbacks.
So expressed in pseudo codes, the above logic is:
if reoslved is not enabled:
link /etc/resolv-conf.systemd to /run/systemd/resolve/resolv.conf
make sure /etc/resolv-conf.systemd is not a dead link
else:
link /etc/resolv-conf.systemd to /run/systemd/resolve/resolv.conf
# systemd-resolved handles /run/systemd/resolve/resolv.conf, so
nothing more needs to be done here
Best Regards,
Chen Qi
On 07/17/2018 06:05 PM, nick83ola wrote:
> Hi
>
> commit 00e4662e55f66570cae29240c22b4d74b79d3ca5
> Author: Maxin B. John <maxin.john at intel.com>
> <mailto:maxin.john at intel.com>
> Date: Mon Jun 12 18:10:21 2017 +0300
>
> systemd: enable resolved and networkd
>
> Enable systemd-resolved and systemd-networkd by default.
> Make it co-exist with connman and Fix associated problems
> in read-only rootfs.
>
>
> This part of the patch does nothing with the current version of
> systemd (or does the wrong thing)
>
>
> else
> sed -i -e "s%^L! /etc/resolv.conf.*$%L!
> /etc/resolv.conf - - - - ../run/systemd/resolve/resolv.conf%g"
> ${D}${exec_prefix}/lib/tmpfiles.d/etc.conf
> + ln -s ../run/systemd/resolve/resolv.conf
> ${D}${sysconfdir}/resolv-conf.systemd
> fi
>
> the check here was
>
> if ! ${@bb.utils.contains('PACKAGECONFIG', 'resolved', 'true',
> 'false', d)}; then
> apart from the part that the check is REVERSED ...
> if the PACKAGECONFIG doesn't contain the resolved option
> systemd-resolved is not build and no modification is done on the
> /lib/tmpfiles/etc/conf
>
> see
> https://github.com/systemd/systemd/blob/46659f7deb962f55c728e70597e37c2a3ab6326d/tmpfiles.d/etc.conf.m4#L16
> m4_ifdef(`ENABLE_RESOLVE',
>
> L! /etc/resolv.conf - - - - ../run/systemd/resolve/stub-resolv.conf
>
> )m4_dnl
>
> So the else branch can be safely removed.
>
> commit 669edd04432f8e76e32bd7f34f4d9aa63eef4038
> Author: Khem Raj <raj.khem at gmail.com> <mailto:raj.khem at gmail.com>
> Date: Fri Dec 16 14:07:31 2016 -0800
>
> systemd: point to correct resolv.conf when resolved is enabled
>
> latest systemd has changed the resolved defaults which points to
> 127.0.0.53 port 53 on local network. If someone wants to use
> host-local IP address then it can be pointed to copy in
> /lib/systemd
>
> (From OE-Core rev: 99d1199fd0961f94732a1a533d66472ca17cf6f5)
>
> Signed-off-by: Khem Raj <raj.khem at gmail.com>
> <mailto:raj.khem at gmail.com>
> Signed-off-by: Ross Burton <ross.burton at intel.com>
> <mailto:ross.burton at intel.com>
> Signed-off-by: Richard Purdie
> <richard.purdie at linuxfoundation.org>
> <mailto:richard.purdie at linuxfoundation.org>
>
>
> So here the error was introduced!!!!! read this patch carefully
> If you read the deleted comment it was saying:
> *if resolved is disabled*,
> But this patch reverse it to
>
> systemd: point to correct resolv.conf when resolved *is enabled*
>
> if ! ${@bb.utils.contains('PACKAGECONFIG', 'resolved', 'true',
> 'false', d)}; then
> - # *if resolved is disabled*, it won't handle the link
> of resolv.conf, so
> - # set it up ourselves
> - ln -s ../run/resolv.conf ${D}${sysconfdir}/resolv.conf
> - echo '*L! ${sysconfdir}/resolv.conf - - - -
> ../run/resolv.conf'* >>${D}${exec_prefix}/lib/tmpfiles.d/etc.conf
> - echo 'f /run/resolv.conf 0644 root root'
> >>${D}${exec_prefix}/lib/tmpfiles.d/systemd.conf
> + echo*'L! ${sysconfdir}/resolv.conf - - - -
> ../run/systemd/resolve/resolv.conf'*
> >>${D}${exec_prefix}/lib/tmpfiles.d/etc.conf
> + echo 'd /run/systemd/resolve 0755 root root -'
> >>${D}${exec_prefix}/lib/tmpfiles.d/systemd.conf
> + echo 'f /run/systemd/resolve/resolv.conf 0644 root
> root' >>${D}${exec_prefix}/lib/tmpfiles.d/systemd.conf
> + ln -s ../run/systemd/resolve/resolv.conf
> ${D}${sysconfdir}/resolv.conf
> + else
> + sed -i -e "s%^L! /etc/resolv.conf.*$%L!
> /etc/resolv.conf - - - - ../run/systemd/resolve/resolv.conf%g"
> ${D}${exec_prefix}/lib/tmpfiles.d/etc.conf
> fi
> install -Dm 0755
> ${S}/src/systemctl/systemd-sysv-install.SKELETON
> ${D}${systemd_unitdir}/systemd-sysv-install
> }
>
>
>
>
>
> commit b80da02ce9b683f96393fe0ea1f5f1a5f1a07c89
> Author: Christopher Larson <chris_larson at mentor.com>
> <mailto:chris_larson at mentor.com>
> Date: Wed Nov 4 20:19:19 2015 -0700
>
> systemd: arrange for volatile /etc/resolv.conf
>
> On sysvinit systems, volatiles is configured to make
> /etc/resolv.conf symlink
> to a file in a volatile path, which lets us write to
> /etc/resolv.conf for
> read-only-rootfs. For systemd, this isn't set up unless we enable
> systemd-resolved, which we don't by default. When it's not
> enabled, create the
> /etc/resolv.conf symlink and ensure the volatile path is
> created on boot with
> tmpfiles.d.
>
>
> + if ! ${@bb.utils.contains('PACKAGECONFIG', 'resolved', 'true',
> 'false', d)}; then
> + # if resolved is disabled, it won't handle the link of
> resolv.conf, so
> + # set it up ourselves
> + ln -s ../run/resolv.conf ${D}${sysconfdir}/resolv.conf
> + echo 'L! ${sysconfdir}/resolv.conf - - - -
> ../run/resolv.conf' >>${D}${exec_prefix}/lib/tmpfiles.d/etc.conf
> + echo 'f /run/resolv.conf 0644 root root'
> >>${D}${exec_prefix}/lib/tmpfiles.d/systemd.conf
> + fi
> install -Dm 0755
> ${S}/src/systemctl/systemd-sysv-install.SKELETON
> ${D}${systemd_unitdir}/systemd-sysv-install
> }
>
> This patch was the right one the following
> 669edd04432f8e76e32bd7f34f4d9aa63eef4038 reversed the sense of the switch
>
> Regards
> Nicola Lunghi
>
> Best Regards,
> Chen Qi
>
>
> On 07/16/2018 04:17 PM, Nicola Lunghi wrote:
>> From: Nicola Lunghi<nicola.lunghi at jci.com> <mailto:nicola.lunghi at jci.com>
>>
>> if resolved option is not selected the package systemd-resolved
>> is not installed so it cannot provide an alternative for
>> resolv.conf
>>
>> In this recipe the previous check was instead reversing the check (note the !).
>>
>> This patch avoid messing with resol.conf link if resolved is disabled in
>> the package config.
>>
>> This in particular if we compile systemd with musl where systemd-resolved
>> cannot be compiled.
>>
>> Signed-off-by: Nicola Lunghi<nicola.lunghi at jci.com> <mailto:nicola.lunghi at jci.com>
>> ---
>> meta/recipes-core/systemd/systemd_237.bb <http://systemd_237.bb> | 8 +++-----
>> 1 file changed, 3 insertions(+), 5 deletions(-)
>>
>> diff --git a/meta/recipes-core/systemd/systemd_237.bb <http://systemd_237.bb> b/meta/recipes-core/systemd/systemd_237.bb <http://systemd_237.bb>
>> index 3efca33e73..bd6dcef637 100644
>> --- a/meta/recipes-core/systemd/systemd_237.bb <http://systemd_237.bb>
>> +++ b/meta/recipes-core/systemd/systemd_237.bb <http://systemd_237.bb>
>> @@ -258,14 +258,11 @@ do_install() {
>> if [ -s ${D}${exec_prefix}/lib/tmpfiles.d/systemd.conf ]; then
>> ${@bb.utils.contains('PACKAGECONFIG', 'networkd', ':', 'sed -i -e "\$ad /run/systemd/netif/links 0755 root root -" ${D}${exec_prefix}/lib/tmpfiles.d/systemd.conf', d)}
>> fi
>> - if ! ${@bb.utils.contains('PACKAGECONFIG', 'resolved', 'true', 'false', d)}; then
>> + if ${@bb.utils.contains('PACKAGECONFIG', 'resolved', 'true', 'false', d)}; then
>> echo 'L! ${sysconfdir}/resolv.conf - - - - ../run/systemd/resolve/resolv.conf' >>${D}${exec_prefix}/lib/tmpfiles.d/etc.conf
>> echo 'd /run/systemd/resolve 0755 root root -' >>${D}${exec_prefix}/lib/tmpfiles.d/systemd.conf
>> echo 'f /run/systemd/resolve/resolv.conf 0644 root root' >>${D}${exec_prefix}/lib/tmpfiles.d/systemd.conf
>> ln -s ../run/systemd/resolve/resolv.conf ${D}${sysconfdir}/resolv-conf.systemd
>> - else
>> - sed -i -e "s%^L! /etc/resolv.conf.*$%L! /etc/resolv.conf - - - - ../run/systemd/resolve/resolv.conf%g" ${D}${exec_prefix}/lib/tmpfiles.d/etc.conf
>> - ln -s ../run/systemd/resolve/resolv.conf ${D}${sysconfdir}/resolv-conf.systemd
>> fi
>> install -Dm 0755 ${S}/src/systemctl/systemd-sysv-install.SKELETON ${D}${systemd_unitdir}/systemd-sysv-install
>>
>> @@ -539,7 +536,7 @@ python __anonymous() {
>> # TODO:
>> # u-a for runlevel and telinit
>>
>> -ALTERNATIVE_${PN} = "init halt reboot shutdown poweroff runlevel resolv-conf"
>> +ALTERNATIVE_${PN} = "init halt reboot shutdown poweroff runlevel"
>>
>> ALTERNATIVE_TARGET[init] = "${rootlibexecdir}/systemd/systemd"
>> ALTERNATIVE_LINK_NAME[init] = "${base_sbindir}/init"
>> @@ -565,6 +562,7 @@ ALTERNATIVE_TARGET[runlevel] = "${base_bindir}/systemctl"
>> ALTERNATIVE_LINK_NAME[runlevel] = "${base_sbindir}/runlevel"
>> ALTERNATIVE_PRIORITY[runlevel] ?= "300"
>>
>> +ALTERNATIVE_${PN} +="${@bb.utils.contains('PACKAGECONFIG', 'resolved', 'resolv-conf',
>> '', d)}"
>> <mailto:$%7B at bb.utils.contains%28%27PACKAGECONFIG%27,%27resolved%27,%27resolv-conf%27,%27%27,d%29%7D>
>> ALTERNATIVE_TARGET[resolv-conf] = "${sysconfdir}/resolv-conf.systemd"
>> ALTERNATIVE_LINK_NAME[resolv-conf] = "${sysconfdir}/resolv.conf"
>> ALTERNATIVE_PRIORITY[resolv-conf] ?= "50"
>
>
> --
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