I think you're fundamentally understanding how these keys come into
existence. They aren't generated randomly on the local monitor; it
uses get-or-create in order to fetch them (and create them if they
don't already exist).
So maybe it's difficult to pre-generate your own keys and plug them
into the system (I don't remember where the initial values come from
in standard deployment scenarios), but once they're set up you don't
need to carefully install your values on all the monitor nodes — they
will fetch the correct values from the monitor cluster.
The coordination problem here is not really any different than that of
making sure your monitors are all part of the "mon initial members"
config option, btw. Which you need to solve or else you're liable to
have them coming up and creating independent monitor clusters and
going haywire.
-Greg
On Tue, Apr 5, 2016 at 4:56 AM, Owen Synge <osynge@xxxxxxxx> wrote:
> Dear all,
>
> This is in my opinion is clearly a bug, but I raise it in the mailing
> list as I expect all admins of ceph will strongly agree, that this makes
> ceph simpler, but developers may feel that since it requires changes to
> more than one repo its not worth doing.
>
> When ever you start the mon demon as a side effect the admin, osd, rgw
> and mds keys are created as a side effect if the mds keyring is not
> existing.
>
> In the systemV and systemd init scripts (at least) we have a side
> effect, that should be removed in my opinion, (or worse in my
> alternatively correctly documented.)
>
> This is a deployment layer violation, in my opinion, and it requires
> considerably more documentation, (and on my part also code) to keep this
> side effect than remove it.
>
> usecases for removing this are:
>
> (0) A ceph cluster should be able to be installed in any order. With the
> current behavior if the mds, rgw, or osd nodes are deployed first (along
> with the boot strap keyrings), the mon created must have all keys for
> the admin, mds-bootstrap, rgw-bootstrap, and osd-boostrap deployed in
> the correct path before the mon can safely be started, even if the
> cluster does not need the mds or rgw service's.
>
> (1) It is unfriendly to configuration being stored on the configuration
> server as the server needs to be updated with the values from the
> configured node keys, when people might want to store these keys centrally.
>
> (2) Assuming the admin, rgw-bootstrap, mds-bootstrap and osd-boostrap
> keys are always installed on all mon nodes is clearly increasing the
> distribution of keys where they might not be needed. Hence reducing
> security.
>
> (3) Using the current model adds an extra complication that these keys
> then need to be distributed to each node from the configured node, if
> generated by starting the mon, and not from the configuration server.
>
> (4) If you wish to use a more devops approach, and generate keys
> explicitly all the keys must be installed on all mon nodes before the
> mon nodes are started.
>
> (4.1) As a side effect we need to document why admins need the
> mds-bootstrap keyring when they dont want this service it is confusing,
> and requires an unnecessary process of migrating all keys to the
> explicitly desired keys.
>
> (5) I am developing a simple python library to configure ceph on each
> node independently of all others, (think of it as a parallelism version
> of ceph-deploy that can be called by any config management system) but
> with the current side effect behavior starting the mon needs to fail if
> the mds-bootstrap keyring is not created on the mon nodes before
> starting the mon, otherwise we get ordering complications.
>
> (5) The side effect is confusing, as no one expects this side effect,
> hence this leads to ceph seeming complex to a first time user.
>
> (6) I feel it is the responsibility of configuration management not the
> mon demon to request creating these keys.
>
> (7) I dont think this is clearly documented, hence this leads to ceph
> seeming complex to a first time user.
>
> (8) As more services like mds and rgw get added to ceph the problem gets
> multiplied.
>
> (9) Adding one more step to the by hand installation will clarify the
> authentication process. This extra step would simply be:
>
> /usr/sbin/ceph-create-keys --cluster ${CLUSTER} --id ${MON_NAME}
>
> This is simpler and clearer than documenting the side effect.
>
> consequences:
>
> (1) Each configuration system which depends upon this behavior will need
> to be modified to call the single command on each mon:
>
> /usr/sbin/ceph-create-keys --cluster ${CLUSTER} --id ${MON_NAME}
>
> Here is a fix for ceph-deploy:
>
> https://github.com/SUSE/ceph-deploy/commit/58b030dbe0a964b32f1fbc9a3762e64dd74bf50c
>
> I assume other solutions will be easy to fix too.
>
> The systemd file in question, is
> "/usr/lib/systemd/system/ceph-create-keys@.service" and should be removed.
>
> This will simplify the salt configuration module documentation
> considerably, and if this is not done the salt module will need to add a
> requirement on the mds keyring being created before the mon can be created.
>
> the systemd file looks as follows:
>
> [Unit]
> Description=Ceph cluster key creator task
>
> # the last key created is the mds bootstrap key -- look for that.
> ConditionPathExists=!/var/lib/ceph/bootstrap-mds/ceph.keyring
>
> [Service]
> EnvironmentFile=-/etc/sysconfig/ceph
> Environment=CLUSTER=ceph
> ExecStart=/usr/sbin/ceph-create-keys --cluster ${CLUSTER} --id %i
>
> as you can see the side effect is blocked if the file
>
> /var/lib/ceph/bootstrap-mds/ceph.keyring
>
> already exists, which is just more to document.
>
> Hoping that you all agree
>
> Owen Synge
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