open-nomad/website/pages/docs/job-specification/csi_plugin.mdx
Tim Gross 3169839653
docs: always use -ignore-system on node drain with CSI (#8606)
Postrun hooks for allocation runners don't currently block the registration of
terminal health with the servers, which is what allows system jobs to be
drained. So draining nodes with jobs that claim CSI volumes requires the
`-ignore-system` job to ensure that the postrun hook for service jobs gets a
chance to execute.
2020-08-07 11:22:28 -04:00

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---
layout: docs
page_title: csi_plugin Stanza - Job Specification
sidebar_title: csi_plugin <sup>Beta</sup>
description: >-
The "csi_plugin" stanza allows the task to specify it provides a
Container Storage Interface plugin to the cluster.
---
# `csi_plugin` Stanza
<Placement groups={['job', 'group', 'task', 'volume']} />
The "csi_plugin" stanza allows the task to specify it provides a
Container Storage Interface plugin to the cluster. Nomad will
automatically register the plugin so that it can be used by other jobs
to claim [volumes][csi_volumes].
```hcl
csi_plugin {
id = "csi-hostpath"
type = "monolith"
mount_dir = "/csi"
}
```
## `csi_plugin` Parameters
- `id` `(string: <required>)` - This is the ID for the plugin. Some
plugins will require both controller and node plugin types (see
below); you need to use the same ID for both so that Nomad knows the
belong to the same plugin.
- `type` `(string: <required>)` - One of `node`, `controller`, or
`monolith`. Each plugin supports one or more types. Each Nomad
client node where you want to mount a volume will need a `node`
plugin instance. Some plugins will also require one or more
`controller` plugin instances to communicate with the storage
provider's APIs. Some plugins can serve as both `controller` and
`node` at the same time, and these are called `monolith`
plugins. Refer to your CSI plugin's documentation.
- `mount_dir` `(string: <required>)` - The directory path inside the
container where the plugin will expect a Unix domain socket for
bidirectional communication with Nomad.
~> **Note:** Plugins running as `node` or `monolith` require root
privileges (or `CAP_SYS_ADMIN` on Linux) to mount volumes on the
host. With the Docker task driver, you can use the `privileged = true`
configuration, but no other default task drivers currently have this
option.
~> **Note:** During node drains, jobs that claim volumes must be moved before
the `node` or `monolith` plugin for those volumes. You should run `node` or
`monolith` plugins as [`system`][system] jobs and use the `-ignore-system`
flag on `nomad node drain` to ensure that the plugins are running while the
node is being drained.
## `csi_plugin` Examples
```hcl
job "plugin-efs" {
datacenters = ["dc1"]
# you can run node plugins as service jobs as well, but running
# as a system job ensures all nodes in the DC have a copy.
type = "system"
group "nodes" {
task "plugin" {
driver = "docker"
config {
image = "amazon/aws-efs-csi-driver:latest"
args = [
"node",
"--endpoint=unix://csi/csi.sock",
"--logtostderr",
"--v=5",
]
# all CSI node plugins will need to run as privileged tasks
# so they can mount volumes to the host. controller plugins
# do not need to be privileged.
privileged = true
}
csi_plugin {
id = "aws-efs0"
type = "node"
mount_dir = "/csi" # this path /csi matches the --endpoint
# argument for the container
}
}
}
}
```
[csi]: https://github.com/container-storage-interface/spec
[csi_volumes]: /docs/job-specification/volume
[system]: /docs/schedulers/#system