Add variable for local IP address to /etc/hosts manager

[Peter Sankauskas]

Hi,
>
> I would like to set first line in the /etc/hosts file to be something like
> this:
>
> local-ip FQDN Hostname
>
> The ip address should be the one returned from `ec2metadata --local-ipv4`.
> After this line, I would like the usual 127.0.0.1 localhost line. I have
> edited the template at /etc/cloud/templates/hosts.tmpl to have:
>
> ## The value '$hostname' will be replaced with the local-hostname
> 10.2.46.37 $fqdn $hostname
> 127.0.0.1 localhost

I guess it would be good to have a variable available for substitution
available. Could you open a bug on cloud-init for that?
http://bugs.launchpad.net/cloud-init/+filebug

> but I do not know how to get the local IP address as a variable to put into
> the template. At the moment, it is hardcoded, which is not ideal.
>
> Does anyone know what variable I can use in the template file?

The hack that I can think of is to add an upstart job or user-data hook
that just does this for you.

Anyone have better ideas?

[Peter Sankauskas (pas256)]

Since this bug is a low priority, I figured I would download the source and figure it out. Attached is my proposed patch where I use netinfo.netdev_info() to get the data need to pass to the template.

This allows the use of variables such as $dev_lo, $dev_eth0, etc (depending on what devices are present on the server) to be used in hosts.ubuntu.tmpl.

Example:
$dev_eth0 $fqdn $hostname
127.0.0.1 localhost

Comments on the patch welcome.

[Peter Sankauskas (pas256)]

The above patch is for version 0.7.0 present on Ubuntu 12.10 Quantal

[Peter Sankauskas (pas256)]

Since Ubuntu 12.04 Precise is an LTS release, here is the patch for it as well.

[Scott Moser (smoser)]

Karate, Peter,
  Could you look at the merge proposal and let me know if it would work for you?
  I do think it would sovel the problem, and incorporates Peter's 'eth0_ip' idea in it, along with allowing for '$local_ipv4'

  https://code.launchpad.net/~smoser/cloud-init/lp1020695/+merge/163216

  I wrote it all out, but felt it was getting heavier than I wanted right before 0.7.2 release, which I want "real soon now".

[Karate Vick (karate-vick)]

Yes, it looks good. Getting the public_ipv4 should do the trick.

K

On Tue, May 14, 2013 at 12:47 PM, Scott Moser <email address hidden> wrote:

> Karate, Peter,
> Could you look at the merge proposal and let me know if it would work
> for you?
> I do think it would sovel the problem, and incorporates Peter's
> 'eth0_ip' idea in it, along with allowing for '$local_ipv4'
>
> https://code.launchpad.net/~smoser/cloud-init/lp1020695/+merge/163216
>
> I wrote it all out, but felt it was getting heavier than I wanted
> right before 0.7.2 release, which I want "real soon now".
>
> --
> You received this bug notification because you are subscribed to the bug
> report.
> https://bugs.launchpad.net/bugs/1020695
>
> Title:
> Add variable for local IP address to /etc/hosts manager
>
> Status in Init scripts for use on cloud images:
> Triaged
>
> Bug description:
> Hi,
> >
> > I would like to set first line in the /etc/hosts file to be something
> like
> > this:
> >
> > local-ip FQDN Hostname
> >
> > The ip address should be the one returned from `ec2metadata
> --local-ipv4`.
> > After this line, I would like the usual 127.0.0.1 localhost line. I
> have
> > edited the template at /etc/cloud/templates/hosts.tmpl to have:
> >
> > ## The value '$hostname' will be replaced with the local-hostname
> > 10.2.46.37 $fqdn $hostname
> > 127.0.0.1 localhost
>
> I guess it would be good to have a variable available for substitution
> available. Could you open a bug on cloud-init for that?
> http://bugs.launchpad.net/cloud-init/+filebug
>
> > but I do not know how to get the local IP address as a variable to put
> into
> > the template. At the moment, it is hardcoded, which is not ideal.
> >
> > Does anyone know what variable I can use in the template file?
>
> The hack that I can think of is to add an upstart job or user-data hook
> that just does this for you.
>
> Anyone have better ideas?
>
> To manage notifications about this bug go to:
> https://bugs.launchpad.net/cloud-init/+bug/1020695/+subscriptions
>

[cristi1979 (cristi-falcas)]

did this get implemented after all?

I don't see it in the rpm from cloud-init 0.7.4 and I was curious if it was pushed or not.

[datakid (datakid)]

This still hasn't made it into 0.7.6. What's going on?

[datakid (datakid)]

Oh I see, the underlying code has been changed. This patch will no longer work.

[Lior Goikhburg (goikhburg)]

Is this ever going to be merged ?

[[e-mail] (eblock)]

I'm currently using version 0.7.8 but the patch is still not there. It would be really useful, I hope it will be merged soon.

[James Falcon (falcojr)]

Tracked in Github Issues as https://github.com/canonical/cloud-init/issues/2270