Libguestfs - Mar 2016 - Re: [PATCH] appliance: Copy /etc/machine-id from host system into the appliance.

Currently when the appliance is booted we see warning messages like
these ones:

[/usr/lib/tmpfiles.d/systemd.conf:26] Failed to replace specifiers:
/run/log/journal/%m
[/usr/lib/tmpfiles.d/systemd.conf:28] Failed to replace specifiers:
/run/log/journal/%m
[/usr/lib/tmpfiles.d/systemd.conf:29] Failed to replace specifiers:
/run/log/journal/%m

They are apparently harmless, but are caused because /etc/machine-id
does not exist inside the appliance, and so %m cannot be substituted
by systemd-tmpfiles.

The solution to this is to provide /etc/machine-id.  However this is
not so simple: either we could get supermin to generate this,
requiring an ugly systemd-specific hack to supermin, or we could
generate it in the /init script, which just slows the init script down
for no real reason.

Since the content of /etc/machine-id doesn't really matter for a
throwaway appliance so long as it has the right format, this commit
copies the host file into the appliance.
---
 appliance/hostfiles.in | 1 +
 1 file changed, 1 insertion(+)

diff --git a/appliance/hostfiles.in b/appliance/hostfiles.in
index 8ff53b5..6c581bd 100644
--- a/appliance/hostfiles.in
+++ b/appliance/hostfiles.in
@@ -13,5 +13,6 @@ dnl   SUSE=1       For OpenSUSE.
 dnl   FRUGALWARE=1 For Frugalware.
 dnl   MAGEIA=1     For Mageia.
 
+/etc/machine-id
 /lib/lsb/*
 /usr/share/augeas/lenses/*.aug
-- 
2.7.4

systemd will generate a new machine-id if /etc/machine-id is empty,
that's how anaconda does it, maybe it's also an option for guestfish.

- fabian

On Tue, Mar 29, 2016 at 1:14 PM, Richard W.M. Jones <rjones@redhat.com>
wrote:
> Currently when the appliance is booted we see warning messages like
> these ones:
>
> [/usr/lib/tmpfiles.d/systemd.conf:26] Failed to replace specifiers:
/run/log/journal/%m
> [/usr/lib/tmpfiles.d/systemd.conf:28] Failed to replace specifiers:
/run/log/journal/%m
> [/usr/lib/tmpfiles.d/systemd.conf:29] Failed to replace specifiers:
/run/log/journal/%m
>
> They are apparently harmless, but are caused because /etc/machine-id
> does not exist inside the appliance, and so %m cannot be substituted
> by systemd-tmpfiles.
>
> The solution to this is to provide /etc/machine-id.  However this is
> not so simple: either we could get supermin to generate this,
> requiring an ugly systemd-specific hack to supermin, or we could
> generate it in the /init script, which just slows the init script down
> for no real reason.
>
> Since the content of /etc/machine-id doesn't really matter for a
> throwaway appliance so long as it has the right format, this commit
> copies the host file into the appliance.
> ---
>  appliance/hostfiles.in | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/appliance/hostfiles.in b/appliance/hostfiles.in
> index 8ff53b5..6c581bd 100644
> --- a/appliance/hostfiles.in
> +++ b/appliance/hostfiles.in
> @@ -13,5 +13,6 @@ dnl   SUSE=1       For OpenSUSE.
>  dnl   FRUGALWARE=1 For Frugalware.
>  dnl   MAGEIA=1     For Mageia.
>
> +/etc/machine-id
>  /lib/lsb/*
>  /usr/share/augeas/lenses/*.aug
> --
> 2.7.4
>
> _______________________________________________
> Libguestfs mailing list
> Libguestfs@redhat.com
> https://www.redhat.com/mailman/listinfo/libguestfs


-- 
Fabian Deutsch <fdeutsch@redhat.com>
RHEV Hypervisor
Red Hat

On Tue, Mar 29, 2016 at 01:16:34PM +0200, Fabian Deutsch
wrote:
> systemd will generate a new machine-id if /etc/machine-id is empty,
> that's how anaconda does it, maybe it's also an option for
guestfish.
If we were running systemd, then I'm sure it would :-)

I'm not opposed in some way to running systemd in the appliance, but
it would have to have only benefits.  We're only running one daemon.

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
Read my programming and virtualization blog: http://rwmj.wordpress.com
virt-builder quickly builds VMs from scratch
http://libguestfs.org/virt-builder.1.html

On Tuesday 29 March 2016 12:14:21 Richard W.M. Jones
wrote:
> Currently when the appliance is booted we see warning messages like
> these ones:
> 
> [/usr/lib/tmpfiles.d/systemd.conf:26] Failed to replace specifiers:
/run/log/journal/%m
> [/usr/lib/tmpfiles.d/systemd.conf:28] Failed to replace specifiers:
/run/log/journal/%m
> [/usr/lib/tmpfiles.d/systemd.conf:29] Failed to replace specifiers:
/run/log/journal/%m
> 
> They are apparently harmless, but are caused because /etc/machine-id
> does not exist inside the appliance, and so %m cannot be substituted
> by systemd-tmpfiles.
> 
> The solution to this is to provide /etc/machine-id.  However this is
> not so simple: either we could get supermin to generate this,
> requiring an ugly systemd-specific hack to supermin, or we could
> generate it in the /init script, which just slows the init script down
> for no real reason.
> 
> Since the content of /etc/machine-id doesn't really matter for a
> throwaway appliance so long as it has the right format, this commit
> copies the host file into the appliance.
> ---
I had a prototype since some months of the solution about generating it
in /init:

diff --git a/appliance/init b/appliance/init
index 28054ab..20c8d24 100755
--- a/appliance/init
+++ b/appliance/init
@@ -85,6 +85,9 @@ fi
 mkdir -p /run/tmpfiles.d
 kmod static-nodes --format=tmpfiles --output=/run/tmpfiles.d/kmod.conf
 
+# Create a machine-id with a random UUID
+dd if=/dev/urandom bs=1 count=16 status=none | od -x -A n | sed -e 's,
,,g' > /etc/machine-id
+
 # Set up tmpfiles (must run after kmod.conf is created above).
 systemd-tmpfiles --prefix=/dev --create --boot
 

Considering that, since a week or so, virtio-rng is used for the
/dev/urandom of the appliance, reading 16 bytes should not cause to
wait for randomness.

-- 
Pino Toscano

On Tue, Mar 29, 2016 at 03:14:15PM +0200, Pino Toscano
wrote:
> +# Create a machine-id with a random UUID
> +dd if=/dev/urandom bs=1 count=16 status=none | od -x -A n | sed -e 's,
,,g' > /etc/machine-id
Out of interest, why read single bytes, and not the whole 16 bytes in
one go?

Rich.


-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
Read my programming and virtualization blog: http://rwmj.wordpress.com
libguestfs lets you edit virtual machines.  Supports shell scripting,
bindings from many languages.  http://libguestfs.org