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.
* state_store: csi volumes/plugins store the index in the txn
* nomad: csi_endpoint_test require index checks need uint64()
* nomad: other tests using int 0 not uint64(0)
* structs: pass index into New, but not other struct methods
* state_store: csi plugin indexes, use new struct interface
* nomad: csi_endpoint_test check index/query meta (on explicit 0)
* structs: NewCSIVolume takes an index arg now
* scheduler/test: NewCSIVolume takes an index arg now
This changeset implements the initial registration and fingerprinting
of CSI Plugins as part of #5378. At a high level, it introduces the
following:
* A `csi_plugin` stanza as part of a Nomad task configuration, to
allow a task to expose that it is a plugin.
* A new task runner hook: `csi_plugin_supervisor`. This hook does two
things. When the `csi_plugin` stanza is detected, it will
automatically configure the plugin task to receive bidirectional
mounts to the CSI intermediary directory. At runtime, it will then
perform an initial heartbeat of the plugin and handle submitting it to
the new `dynamicplugins.Registry` for further use by the client, and
then run a lightweight heartbeat loop that will emit task events
when health changes.
* The `dynamicplugins.Registry` for handling plugins that run
as Nomad tasks, in contrast to the existing catalog that requires
`go-plugin` type plugins and to know the plugin configuration in
advance.
* The `csimanager` which fingerprints CSI plugins, in a similar way to
`drivermanager` and `devicemanager`. It currently only fingerprints
the NodeID from the plugin, and assumes that all plugins are
monolithic.
Missing features
* We do not use the live updates of the `dynamicplugin` registry in
the `csimanager` yet.
* We do not deregister the plugins from the client when they shutdown
yet, they just become indefinitely marked as unhealthy. This is
deliberate until we figure out how we should manage deploying new
versions of plugins/transitioning them.
