Intercepting invoke-rc.d through policy-rc.d or runit-run from ubuntu ?

[olivier...@telecom-sudparis.eu]

Hi.

I'm installing applications (Debian packages) which configure other services and require restarts during postinsts, or through the course of a functionnal test suite.

These will typically use invoke-rc.d on a traditionnal Debian system.

However, once inside a debian docker container, the policy-rc.d installed by mkimage-debootstrap.sh will disable such invocations.

I'm thinking that maybe baseimage-docker could provide an improved policy-rc.d since it relies on runit, maybe using Ubuntu's runit-run package.

Has anyone attempted this ? Would it make sense ?

Thanks in advance.

Best regards,

[Hongli Lai]

I don't think it would make sense. Runit works very differently than
Upstart. Creating a custom policy-rc.d that integrates with Runit
would probably cause more problems than it solves.

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[Olivier Berger]

Hi.

Hongli Lai <hon...@phusion.nl> writes:

> I don't think it would make sense. Runit works very differently than
> Upstart. Creating a custom policy-rc.d that integrates with Runit
> would probably cause more problems than it solves.
>

I agree it's not necessarily usfeul in all cases, but I do have a need
for this in the case when I'm testing Debian packages whose postinst
scripts tend to ask restart of services like apache or postgresql, using
invoke-rc.d.
Now, with upstart it may be different, but on Debian, it's not yet (and
probably won't be) upstart, so there's clearly a use case.

The interesting feature of sv is that you can symlink /etc/init.d/
scripts to it and it works (upstream feature apparently).

You'll find at
https://fusionforge.org/plugins/scmgit/cgi-bin/gitweb.cgi?p=fusionforge/users/olberger.git;a=blob;f=vm/docker/policy-rc.d;h=acf10b5bb2159044f3c94fc90d6943d98b226d2d;hb=refs/heads/docker
an example of such a policy-rc.d script, which allows me to intercept
calls to invoke-rc.d in package postinst script and divert them
("silently") to sv invocations.

Hope this helps.

Best regards,
--
Olivier BERGER
http://www-public.telecom-sudparis.eu/~berger_o/ - OpenPGP-Id: 2048R/5819D7E8
Ingenieur Recherche - Dept INF
Institut Mines-Telecom, Telecom SudParis, Evry (France)

[Hongli Lai]

Can't you restart those services manually? Why do you need the
packages to automatically restart them for you? I know it's a bit less
convenient than doing it manually but a lot less things can go wrong.

The symlink feature is cool, I didn't know about it. However it would
be hard to make it work in the general case. Not all sysvinit services
should be running when in a Docker container.

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[Olivier Berger]

Hongli Lai <hon...@phusion.nl> writes:

> Can't you restart those services manually? Why do you need the
> packages to automatically restart them for you? I know it's a bit less
> convenient than doing it manually but a lot less things can go wrong.
>

My use case is testing installation of applications inside docker, like
FusionForge, which reconfigures postgresql and apache2, then passing its
test suite that stops postgres, restores DB backup, restarts it, etc.

> The symlink feature is cool, I didn't know about it. However it would
> be hard to make it work in the general case. Not all sysvinit services
> should be running when in a Docker container.
>

Sure.

In any case, if anyone is interested, hopefuly, they'll notice the
discussion and will make good use of this.