[ovs-dev] [PATCH 1/3] ovs-ctl: fallback to "uname -n" for fetching hostname

[Aaron Conole]

Yousong Zhou <yszhou4tech at gmail.com> writes:

> On Fri, 30 Nov 2018 at 23:23, Aaron Conole <aconole at redhat.com> wrote:
>>
>> Yousong Zhou <yszhou4tech at gmail.com> writes:
>>
>> > From: Yousong Zhou <yszhou4tech at gmail.com>
>> >
>> > The command "hostname" is not available in OpenWrt by default.  Strace
>> > result of hostname-3.13 on centos7 shows that bare "hostname" command
>> > calls uname() to fetch node name.
>> >
>> > Signed-off-by: Yousong Zhou <yszhou4tech at gmail.com>
>> > ---
>> >  utilities/ovs-ctl.in | 2 +-
>> >  1 file changed, 1 insertion(+), 1 deletion(-)
>> >
>> > diff --git a/utilities/ovs-ctl.in b/utilities/ovs-ctl.in
>> > index e42f0f1e6..7f2b17b06 100644
>> > --- a/utilities/ovs-ctl.in
>> > +++ b/utilities/ovs-ctl.in
>> > @@ -40,7 +40,7 @@ set_hostname () {
>> >      # call this only after ovs-vswitchd is running.
>> >      hn="$(hostname -f)"
>> >      if test X$FULL_HOSTNAME = Xno; then
>> > -        hn="$(hostname)"
>> > +        hn="$(uname -n)"
>> >      fi
>>
>> Should we also modify the call to 'hostname' above, too?  ie:
>>
>> -     hn="$(hostname -f)"
>> +     hn="$(uname -n)"
>>
>> I don't know since uname -n is always the same as hostname -f,
>> iirc.  That makes the option (FULL_HOSTNAME=no) look strange.
>>
>> Actually, that makes me think that the hn="$(hostname)" might need to
>> have been 'hostname -s' - but I'm not sure.
>
> On my centos7 machine, `hostname -f` will try to form and verify fqdn
> by reading "domain" from /etc/resolv.conf and doing dns query.  I
> think the output of "uname -n" is same as with "sysctl -n
> kernel.hostname"

Still, I think the hostname call above should be reworked.  Maybe
something like:

  hn="$(uname -n)"
  if test X$FULL_HOSTNAME = Xyes; then
      hn=$(hostname -f)
  fi

Just a thought.  If hostname doesn't exist, then you're going to always
invoke it as-is.  Maybe I'm misunderstanding something, though.  WDYT?

>                 yousong