nodepool/doc/source/openshift-pods.rst
James E. Blair c78fe769f2 Allow custom k8s pod specs
This change adds the ability to use the k8s (and friends) drivers
to create pods with custom specs.  This will allow nodepool admins
to define labels that create pods with options not otherwise supported
by Nodepool, as well as pods with multiple containers.

This can be used to implement the versatile sidecar pattern, which,
in a system where it is difficult to background a system process (such
as a database server or container runtime) is useful to run jobs with
such requirements.

It is still the case that a single resource is returned to Zuul, so
a single pod will be added to the inventory.  Therefore, the expectation
that it should be possible to shell into the first container in the
pod is documented.

Change-Id: I4a24a953a61239a8a52c9e7a2b68a7ec779f7a3d
2024-01-30 15:59:34 -08:00

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15 KiB
ReStructuredText

.. _openshift-pods-driver:
.. default-domain:: zuul
Openshift Pods Driver
---------------------
Selecting the openshift pods driver adds the following options to the
:attr:`providers` section of the configuration.
.. attr:: providers.[openshiftpods]
:type: list
The Openshift Pods driver is similar to the Openshift driver, but it
only supports pod label. This enables using an unprivileged service account
that doesn't require the self-provisioner role.
Example:
.. code-block:: yaml
providers:
- name: cluster
driver: openshiftpods
context: unprivileged-context-name
pools:
- name: main
labels:
- name: openshift-pod
image: docker.io/fedora:28
.. attr:: context
:required:
Name of the context configured in ``kube/config``.
Before using the driver, Nodepool services need a ``kube/config`` file
manually installed.
Make sure the context is present in ``oc config get-contexts`` command
output.
.. attr:: launch-retries
:default: 3
The number of times to retry launching a pod before considering
the job failed.
.. attr:: max-pods
:default: infinite
:type: int
An alias for `max-servers`.
.. attr:: max-cores
:type: int
:default: unlimited
Maximum number of cores usable from this provider's pools by
default. This can be used to limit usage of the openshift
backend. If not defined nodepool can use all cores up to the
limit of the backend.
.. attr:: max-servers
:type: int
:default: unlimited
Maximum number of pods spawnable from this provider's pools by
default. This can be used to limit the number of pods. If not
defined nodepool can create as many servers the openshift
backend allows.
.. attr:: max-ram
:type: int
:default: unlimited
Maximum ram usable from this provider's pools by default. This
can be used to limit the amount of ram allocated by nodepool. If
not defined nodepool can use as much ram as the openshift
backend allows.
.. attr:: max-resources
:type: dict
:default: unlimited
A dictionary of other quota resource limits applicable to this
provider's pools by default. Arbitrary limits may be supplied
with the
:attr:`providers.[openshiftpods].pools.labels.extra-resources`
attribute.
.. attr:: pools
:type: list
A pool defines a group of resources from an Openshift provider.
.. attr:: name
:required:
The project's (namespace) name that will be used to create the pods.
.. attr:: priority
:type: int
:default: 100
The priority of this provider pool (a lesser number is a higher
priority). Nodepool launchers will yield requests to other
provider pools with a higher priority as long as they are not
paused. This means that in general, higher priority pools will
reach quota first before lower priority pools begin to be used.
This setting may be specified at the provider level in order
to apply to all pools within that provider, or it can be
overridden here for a specific pool.
.. attr:: node-attributes
:type: dict
A dictionary of key-value pairs that will be stored with the node data
in ZooKeeper. The keys and values can be any arbitrary string.
.. attr:: max-cores
:type: int
Maximum number of cores usable from this pool. This can be used
to limit usage of the kubernetes backend. If not defined nodepool can
use all cores up to the limit of the backend.
.. attr:: max-servers
:type: int
Maximum number of pods spawnable from this pool. This can
be used to limit the number of pods. If not defined
nodepool can create as many servers the kubernetes backend allows.
.. attr:: max-ram
:type: int
Maximum ram usable from this pool. This can be used to limit
the amount of ram allocated by nodepool. If not defined
nodepool can use as much ram as the kubernetes backend allows.
.. attr:: max-resources
:type: dict
:default: unlimited
A dictionary of other quota resource limits applicable to
this pool. Arbitrary limits may be supplied with the
:attr:`providers.[openshiftpods].pools.labels.extra-resources` attribute.
.. attr:: default-label-cpu
:type: int
Specifies specifies a default value for
:attr:`providers.[openshiftpods].pools.labels.cpu` for all
labels of this pool that do not set their own value.
.. attr:: default-label-memory
:type: int
Specifies a default value in MiB for
:attr:`providers.[openshiftpods].pools.labels.memory` for all
labels of this pool that do not set their own value.
.. attr:: default-label-storage
:type: int
Specifies a default value in MB for
:attr:`providers.[openshiftpods].pools.labels.storage` for all
labels of this pool that do not set their own value.
.. attr:: default-label-cpu-limit
:type: int
Specifies specifies a default value for
:attr:`providers.[openshiftpods].pools.labels.cpu-limit` for all
labels of this pool that do not set their own value.
.. attr:: default-label-memory-limit
:type: int
Specifies a default value in MiB for
:attr:`providers.[openshiftpods].pools.labels.memory-limit` for
all labels of this pool that do not set their own value.
.. attr:: default-label-storage-limit
:type: int
Specifies a default value in MB for
:attr:`providers.[openshiftpods].pools.labels.storage-limit` for
all labels of this pool that do not set their own value.
.. attr:: labels
:type: list
Each entry in a pool`s `labels` section indicates that the
corresponding label is available for use in this pool.
Each entry is a dictionary with the following keys
.. attr:: name
:required:
Identifier for this label; references an entry in the
:attr:`labels` section.
.. attr:: image
The image name.
.. attr:: image-pull
:default: IfNotPresent
:type: str
The ImagePullPolicy, can be IfNotPresent, Always or Never.
.. attr:: image-pull-secrets
:default: []
:type: list
The imagePullSecrets needed to pull container images from a private
registry.
Example:
.. code-block:: yaml
labels:
- name: openshift-pod
type: pod
image: docker.io/fedora:28
image-pull-secrets:
- name: registry-secret
.. attr:: labels
:type: dict
A dictionary of additional values to be added to the
namespace or pod metadata. The value of this field is
added to the `metadata.labels` field in OpenShift. Note
that this field contains arbitrary key/value pairs and is
unrelated to the concept of labels in Nodepool.
.. attr:: dynamic-labels
:type: dict
:default: None
Similar to
:attr:`providers.[openshiftpods].pools.labels.labels`,
but is interpreted as a format string with the following
values available:
* request: Information about the request which prompted the
creation of this node (note that the node may ultimately
be used for a different request and in that case this
information will not be updated).
* id: The request ID.
* labels: The list of labels in the request.
* requestor: The name of the requestor.
* requestor_data: Key/value information from the requestor.
* relative_priority: The relative priority of the request.
* event_id: The external event ID of the request.
* created_time: The creation time of the request.
* tenant_name: The name of the tenant associated with the
request.
For example:
.. code-block:: yaml
labels:
- name: pod-fedora
dynamic-labels:
request_info: "{request.id}"
.. attr:: annotations
:type: dict
A dictionary of additional values to be added to the
pod metadata. The value of this field is
added to the `metadata.annotations` field in OpenShift.
This field contains arbitrary key/value pairs that can be accessed
by tools and libraries. E.g custom schedulers can make use of this
metadata.
.. attr:: cpu
:type: int
Specifies the number of cpu to request for the pod. If no
limit is specified, this will also be used as the limit.
.. attr:: memory
:type: int
Specifies the amount of memory in MiB to request for the
pod. If no limit is specified, this will also be used as
the limit.
.. attr:: storage
:type: int
Specifies the amount of ephemeral-storage in MB to request
for the pod. If no limit is specified, this will also be
used as the limit.
.. attr:: extra-resources
:type: dict
Specifies any extra resources that Nodepool should
consider in its quota calculation other than the resources
described above (cpu, memory, storage).
.. attr:: cpu-limit
:type: int
Specifies the cpu limit for the pod.
.. attr:: memory-limit
:type: int
Specifies the memory limit in MiB for the pod.
.. attr:: storage-limit
:type: int
Specifies the ephemeral-storage limit in MB for the pod.
.. attr:: gpu
:type: float
Specifies the amount of gpu allocated to the pod.
This will be used to set both requests and limits to the same
value, based on how kubernetes assigns gpu resources:
https://kubernetes.io/docs/tasks/manage-gpus/scheduling-gpus/.
.. attr:: gpu-resource
:type: str
Specifies the custom schedulable resource
associated with the installed gpu that is available
in the cluster.
.. attr:: python-path
:type: str
:default: auto
The path of the default python interpreter. Used by Zuul to set
``ansible_python_interpreter``. The special value ``auto`` will
direct Zuul to use inbuilt Ansible logic to select the
interpreter on Ansible >=2.8, and default to
``/usr/bin/python2`` for earlier versions.
.. attr:: shell-type
:type: str
:default: sh
The shell type of the node's default shell executable. Used by Zuul
to set ``ansible_shell_type``. This setting should only be used
- For a windows pod with the experimental `connection-type`
``ssh``, in which case ``cmd`` or ``powershell`` should be set
and reflect the node's ``DefaultShell`` configuration.
- If the default shell is not Bourne compatible (sh), but instead
e.g. ``csh`` or ``fish``, and the user is aware that there is a
long-standing issue with ``ansible_shell_type`` in combination
with ``become``
.. attr:: env
:type: list
:default: []
A list of environment variables to pass to the Pod.
.. attr:: name
:type: str
:required:
The name of the environment variable passed to the Pod.
.. attr:: value
:type: str
:required:
The value of the environment variable passed to the Pod.
.. attr:: node-selector
:type: dict
A map of key-value pairs to ensure the OpenShift scheduler
places the Pod on a node with specific node labels.
.. attr:: scheduler-name
:type: str
Sets the `schedulerName` field on the container. Normally
left unset for the OpenShift default.
.. attr:: privileged
:type: bool
Sets the `securityContext.privileged` flag on the
container. Normally left unset for the OpenShift default.
.. attr:: volumes
:type: list
Sets the `volumes` field on the pod. If supplied, this
should be a list of OpenShift Pod Volume definitions.
.. attr:: volume-mounts
:type: list
Sets the `volumeMounts` flag on the container. If
supplied, this should be a list of OpenShift Container
VolumeMount definitions.
.. attr:: spec
:type: dict
This attribute is exclusive with all other label
attributes except
:attr:`providers.[openshiftpods].pools.labels.name`
:attr:`providers.[openshiftpods].pools.labels.annotations`,
:attr:`providers.[openshiftpods].pools.labels.labels` and
:attr:`providers.[openshiftpods].pools.labels.dynamic-labels`.
If a `spec` is provided, then Nodepool will supply the
contents of this value verbatim to OpenShift as the
``spec`` attribute of the OpenShift ``Pod`` definition.
No other Nodepool attributes are used, including any
default values set at the provider level (such as
`default-label-cpu` and similar).
This attribute allows for the creation of arbitrary
complex pod definitions but the user is responsible for
ensuring that they are suitable. The first container in
the pod is expected to be a long-running container that
hosts a shell environment for running commands. The
following minimal definition matches what Nodepool itself
normally creates and is recommended as a starting point:
.. code-block:: yaml
labels:
- name: custom-pod
spec:
containers:
- name: custom-pod
image: ubuntu:jammy
imagePullPolicy: IfNotPresent
command: ["/bin/sh", "-c"]
args: ["while true; do sleep 30; done;"]