Currently the handling of CSINode RPCs does not correctly handle
forwarding RPCs to Nodes.
This commit fixes this by introducing a shim RPC
(nomad/client_csi_enpdoint) that will correctly forward the request to
the owning node, or submit the RPC to the client.
In the process it also cleans up handling a little bit by adding the
`CSIControllerQuery` embeded struct for required forwarding state.
The CSIControllerQuery embeding the requirement of a `PluginID` also
means we could move node targetting into the shim RPC if wanted in the
future.
When an alloc is marked terminal (and after node unstage/unpublish
have been called), the client syncs the terminal alloc state with the
server via `Node.UpdateAlloc RPC`.
For each job that has a terminal alloc, the `Node.UpdateAlloc` RPC
handler at the server will emit an eval for a new core job to garbage
collect CSI volume claims. When this eval is handled on the core
scheduler, it will call a `volumeReap` method to release the claims
for all terminal allocs on the job.
The volume reap will issue a `ControllerUnpublishVolume` RPC for any
node that has no alloc claiming the volume. Once this returns (or
is skipped), the volume reap will send a new `CSIVolume.Claim` RPC
that releases the volume claim for that allocation in the state store,
making it available for scheduling again.
This same `volumeReap` method will be called from the core job GC,
which gives us a second chance to reclaim volumes during GC if there
were controller RPC failures.
Currently, the client has to ship an entire allocation to the server as
part of performing a VolumeClaim, this has a few problems:
Firstly, it means the client is sending significantly more data than is
required (an allocation contains the entire contents of a Nomad job,
alongside other irrelevant state) which has a non-zero (de)serialization
cost.
Secondly, because the allocation was never re-fetched from the state
store, it means that we were potentially open to issues caused by stale
state on a misbehaving or malicious client.
The change removes both of those issues at the cost of a couple of more
state store lookups, but they should be relatively cheap.
We also now provide the CSIVolume in the response for a claim, so the
client can perform a Claim without first going ahead and fetching all of
the volumes.
This PR implements some intitial support for doing deeper validation of
a volume during its registration with the server. This allows us to
validate the capabilities before users attempt to use the volumes during
most cases, and also prevents registering volumes without first setting
up a plugin, which should help to catch typos and the like during
registration.
This does have the downside of requiring users to wait for (1) instance
of a plugin to be running in their cluster before they can register
volumes.
Nomad servers need to make requests to CSI controller plugins running
on a client for publish/unpublish. The RPC needs to look up the client
node based on the plugin, load balancing across controllers, and then
perform the required client RPC to that node (via server forwarding if
neccessary).
This commit refactors the ACL code for the CSI endpoint to support
environments that run without acls enabled (e.g developer environments)
and also provides an easy way to restrict which endpoints may be
accessed with a client's SecretID to limit the blast radius of a
malicious client on the state of the environment.
When the client receives an allocation which includes a CSI volume,
the alloc runner will block its main `Run` loop. The alloc runner will
issue a `VolumeClaim` RPC to the Nomad servers. This changeset
implements the portions of the `VolumeClaim` RPC endpoint that have
not been previously completed.
Danielle Lancashire