Re: [atomic-devel] We have a bugzilla requesting that we change the default CMD to systemd for base images in RHEL

[Jan Pazdziora <jpazdziora redhat com>]

On Fri, Oct 21, 2016 at 11:50:36AM -0400, Daniel J Walsh wrote:
> If we make this change, we would want to do it in Fedora and Centos also. 
> 
> https://bugzilla.redhat.com/show_bug.cgi?id=1387282
> 
> The benefits of making this change are that people new to containers
> could follow a simple workflow similar to what the do on the OS, where
> all they need to do is install an rpm service and enable and it is ready
> to go.

Could we focus on making systemd lean and easy in container without
the CMD change first?

The current fedora:24 image needs -e container=docker to even docker
run with /usr/sbin/init.

We should also minimize the number of targets / services that run in
container by default:

$ docker run -e container=docker --rm -ti fedora:24 /usr/sbin/init
systemd 229 running in system mode. (+PAM +AUDIT +SELINUX +IMA -APPARMOR +SMACK +SYSVINIT +UTMP +LIBCRYPTSETUP +GCRYPT +GNUTLS +ACL +XZ +LZ4 +SECCOMP +BLKID +ELFUTILS +KMOD +IDN)
Detected virtualization docker.
Detected architecture x86-64.

Welcome to Fedora 24 (Twenty Four)!

Set hostname to <a12fa410b8f2>.
[  OK  ] Created slice System Slice.
[  OK  ] Reached target Encrypted Volumes.
[  OK  ] Listening on /dev/initctl Compatibility Named Pipe.
[  OK  ] Reached target Local File Systems.
[  OK  ] Reached target Remote File Systems.
[  OK  ] Started Dispatch Password Requests to Console Directory Watch.
[  OK  ] Reached target Slices.
[  OK  ] Reached target Swap.
[  OK  ] Listening on Journal Socket (/dev/log).
[  OK  ] Listening on Journal Socket.
         Starting Rebuild Dynamic Linker Cache...
         Starting Rebuild Journal Catalog...
         Starting Load/Save Random Seed...
[  OK  ] Listening on Process Core Dump Socket.
         Starting Create System Users...
[  OK  ] Started Forward Password Requests to Wall Directory Watch.
[  OK  ] Reached target Paths.
         Starting Journal Service...
[  OK  ] Started Load/Save Random Seed.
[  OK  ] Started Rebuild Journal Catalog.
[  OK  ] Started Create System Users.
[  OK  ] Started Journal Service.
         Starting Flush Journal to Persistent Storage...
[  OK  ] Started Rebuild Dynamic Linker Cache.
         Starting Update is Completed...
[  OK  ] Started Update is Completed.
[  OK  ] Started Flush Journal to Persistent Storage.
         Starting Create Volatile Files and Directories...
[  OK  ] Started Create Volatile Files and Directories.
         Starting Update UTMP about System Boot/Shutdown...
[  OK  ] Started Update UTMP about System Boot/Shutdown.
[  OK  ] Reached target System Initialization.
[  OK  ] Started Daily Cleanup of Temporary Directories.
[  OK  ] Listening on D-Bus System Message Bus Socket.
[  OK  ] Reached target Sockets.
[  OK  ] Started dnf makecache timer.
[  OK  ] Reached target Basic System.
[  OK  ] Started D-Bus System Message Bus.
         Starting Permit User Sessions...
[  OK  ] Reached target Timers.
[  OK  ] Started Permit User Sessions.
[  OK  ] Reached target Multi-User System.
         Starting Update UTMP about System Runlevel Changes...
[  OK  ] Started Update UTMP about System Runlevel Changes.

There are also other incompatibilities that we might want to resolve
first, like

	https://bugzilla.redhat.com/show_bug.cgi?id=1373780

Overall, I think that in-container systemd behaviour should be made rock
solid before making change of the default.

-- 
Jan Pazdziora
Senior Principal Software Engineer, Identity Management Engineering, Red Hat