openstack/nova
Code Issues Proposed changes

API microversion 2.69: Handles Down Cells Documentation

Browse Source 
This patch adds the documentation around the work regarding
handling down cells that was introduced in v2.69.

Related to blueprint handling-down-cell

Change-Id: I78ed924a802307a992ff90e61ae7ff07c2cc39d1
This commit is contained in:
Surya Seetharaman 2019-02-06 13:17:36 +01:00 committed by Dan Smith
parent d2a87a4446
commit 833af5c9bf
9 changed files with 413 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

334
api-guide/source/down_cells.rst Normal file
View File

@ -0,0 +1,334 @@
===================
Handling Down Cells
===================
Starting from microversion 2.69 if there are transient conditions in a
deployment like partial infrastructure failures (for example a cell
not being reachable), some API responses may contain partial results
(i.e. be missing some keys). The server operations which exhibit this
behavior are described below:
* List Servers (GET /servers): This operation may give partial
constructs from the non-responsive portion of the infrastructure. A
typical response, while listing servers from unreachable parts of
the infrastructure, would include only the following keys from
available information:
- status: The state of the server which will be "UNKNOWN".
- id: The UUID of the server.
- links: Links to the servers in question.
A sample response for a GET /servers request that includes one
result each from an unreachable and a healthy part of the
infrastructure is shown below.
Response::
{
"servers": [
{
"status": "UNKNOWN",
"id": "bcc6c6dd-3d0a-4633-9586-60878fd68edb",
"links": [
{
"rel": "self",
"href": "http://openstack.example.com/v2/6f70656e737461636b20342065766572/servers/bcc6c6dd-3d0a-4633-9586-60878fd68edb"
},
{
"rel": "bookmark",
"href": "http://openstack.example.com/6f70656e737461636b20342065766572/servers/bcc6c6dd-3d0a-4633-9586-60878fd68edb"
}
]
},
{
"id": "22c91117-08de-4894-9aa9-6ef382400985",
"name": "test_server",
"links": [
{
"rel": "self",
"href": "http://openstack.example.com/v2/6f70656e737461636b20342065766572/servers/22c91117-08de-4894-9aa9-6ef382400985"
},
{
"rel": "bookmark",
"href": "http://openstack.example.com/6f70656e737461636b20342065766572/servers/22c91117-08de-4894-9aa9-6ef382400985"
}
]
}
]
}
* List Servers Detailed (GET /servers/detail): This operation may give
partial constructs from the non-responsive portion of the
infrastructure. A typical response, while listing servers from
unreachable parts of the infrastructure, would include only the
following keys from available information:
- status: The state of the server which will be "UNKNOWN".
- id: The UUID of the server.
- tenant_id: The tenant_id to which the server belongs to.
- created: The time of server creation.
- links: Links to the servers in question.
A sample response for a GET /servers/details request that includes
one result each from an unreachable and a healthy part of the
infrastructure is shown below.
Response::
{
"servers": [
{
"created": "2018-06-29T15:07:29Z",
"status": "UNKNOWN",
"tenant_id": "940f47b984034c7f8f9624ab28f5643c",
"id": "bcc6c6dd-3d0a-4633-9586-60878fd68edb",
"links": [
{
"href": "http://openstack.example.com/v2.1/6f70656e737461636b20342065766572/servers/bcc6c6dd-3d0a-4633-9586-60878fd68edb",
"rel": "self"
},
{
"href": "http://openstack.example.com/6f70656e737461636b20342065766572/servers/bcc6c6dd-3d0a-4633-9586-60878fd68edb",
"rel": "bookmark"
}
]
},
{
"OS-DCF:diskConfig": "AUTO",
"OS-EXT-AZ:availability_zone": "nova",
"OS-EXT-SRV-ATTR:host": "compute",
"OS-EXT-SRV-ATTR:hostname": "new-server-test",
"OS-EXT-SRV-ATTR:hypervisor_hostname": "fake-mini",
"OS-EXT-SRV-ATTR:instance_name": "instance-00000001",
"OS-EXT-SRV-ATTR:kernel_id": "",
"OS-EXT-SRV-ATTR:launch_index": 0,
"OS-EXT-SRV-ATTR:ramdisk_id": "",
"OS-EXT-SRV-ATTR:reservation_id": "r-y0w4v32k",
"OS-EXT-SRV-ATTR:root_device_name": "/dev/sda",
"OS-EXT-SRV-ATTR:user_data": "IyEvYmluL2Jhc2gKL2Jpbi9zdQplY2hvICJJIGFtIGluIHlvdSEiCg==",
"OS-EXT-STS:power_state": 1,
"OS-EXT-STS:task_state": null,
"OS-EXT-STS:vm_state": "active",
"OS-SRV-USG:launched_at": "2017-10-10T15:49:09.516729",
"OS-SRV-USG:terminated_at": null,
"accessIPv4": "1.2.3.4",
"accessIPv6": "80fe::",
"addresses": {
"private": [
{
"OS-EXT-IPS-MAC:mac_addr": "aa:bb:cc:dd:ee:ff",
"OS-EXT-IPS:type": "fixed",
"addr": "192.168.0.3",
"version": 4
}
]
},
"config_drive": "",
"created": "2017-10-10T15:49:08Z",
"description": null,
"flavor": {
"disk": 1,
"ephemeral": 0,
"extra_specs": {
"hw:cpu_policy": "dedicated",
"hw:mem_page_size": "2048"
},
"original_name": "m1.tiny.specs",
"ram": 512,
"swap": 0,
"vcpus": 1
},
"hostId": "2091634baaccdc4c5a1d57069c833e402921df696b7f970791b12ec6",
"host_status": "UP",
"id": "569f39f9-7c76-42a1-9c2d-8394e2638a6d",
"image": {
"id": "70a599e0-31e7-49b7-b260-868f441e862b",
"links": [
{
"href": "http://openstack.example.com/6f70656e737461636b20342065766572/images/70a599e0-31e7-49b7-b260-868f441e862b",
"rel": "bookmark"
}
]
},
"key_name": null,
"links": [
{
"href": "http://openstack.example.com/v2.1/6f70656e737461636b20342065766572/servers/569f39f9-7c76-42a1-9c2d-8394e2638a6d",
"rel": "self"
},
{
"href": "http://openstack.example.com/6f70656e737461636b20342065766572/servers/569f39f9-7c76-42a1-9c2d-8394e2638a6d",
"rel": "bookmark"
}
],
"locked": false,
"metadata": {
"My Server Name": "Apache1"
},
"name": "new-server-test",
"os-extended-volumes:volumes_attached": [],
"progress": 0,
"security_groups": [
{
"name": "default"
}
],
"status": "ACTIVE",
"tags": [],
"tenant_id": "6f70656e737461636b20342065766572",
"trusted_image_certificates": [
"0b5d2c72-12cc-4ba6-a8d7-3ff5cc1d8cb8",
"674736e3-f25c-405c-8362-bbf991e0ce0a"
],
"updated": "2017-10-10T15:49:09Z",
"user_id": "fake"
}
]
}
**Edge Cases**
* **Filters:** If the user is listing servers using filters, results
from unreachable parts of the infrastructure cannot be tested for
matching those filters and thus no minimalistic construct will be
provided. Note that by default ``openstack server list`` uses the
``deleted=False`` and ``project_id=tenant_id`` filters and since
we know both of these fundamental values at all times, they are
the only allowed filters to be applied to servers with only
partial information available. Hence only doing ``openstack
server list`` and ``openstack server list --all-projects`` (admin
only) will show minimalistic results when parts of the
infrastructure are unreachable. Other filters like ``openstack
server list --deleted`` or ``openstack server list --host xx``
will skip the results depending on the administrator's
configuration of the deployment. Note that the filter ``openstack
server list --limit`` will also skip the results and if not
specified will return 1000 (or the configured default) records
from the available parts of the infrastructure.
* **Marker:** If the user does ``openstack server list --marker`` it will
fail with a 500 if the marker is an instance that is no longer reachable.
* **Sorting:** We exclude the unreachable parts of the infrastructure just like
we do for filters since there is no way of obtaining valid sorted results from
those parts with missing information.
* **Paging:** We ignore the parts of the deployment which are non-responsive.
For example if we have three cells A (reachable state), B (unreachable state)
and C (reachable state) and if the marker is half way in A, we would get the
remaining half of the results from A, all the results from C and ignore cell B.
.. note:: All the edge cases that are not supported for minimal constructs would
give responses based on the administrator's configuration of the deployment,
either skipping those results or returning an error.
* Show Server Details (GET /servers/{server_id}): This operation may
give partial constructs from the non-responsive portion of the
infrastructure. A typical response while viewing a server from an
unreachable part of the infrastructure would include only the
following keys from available information:
- status: The state of the server which will be "UNKNOWN".
- id: The UUID of the server.
- tenant_id: The tenant_id to which the server belongs to.
- created: The time of server creation.
- user_id: The user_id to which the server belongs to. This may be "UNKNOWN"
for older servers.
- image: The image details of the server. If it is not set like
in the boot-from-volume case, this value will be an empty string.
- flavor: The flavor details of the server.
- availability_zone: The availability_zone of the server if it was specified
during during boot time and "UNKNOWN" otherwise.
- power_state: Its value will be 0 (``NOSTATE``).
A sample response for a GET /servers/{server_id} request that
includes one server from an unreachable part of the infrastructure
is shown below.
Response::
{
"server": [
{
"created": "2018-06-29T15:07:29Z",
"status": "UNKNOWN",
"tenant_id": "940f47b984034c7f8f9624ab28f5643c",
"id": "bcc6c6dd-3d0a-4633-9586-60878fd68edb",
"user_id": "940f47b984034c7f8f9624ab28f5643c",
"image": {
"id": "70a599e0-31e7-49b7-b260-868f441e862b",
},
"flavor": {
"disk": 1,
"ephemeral": 0,
"extra_specs": {
"hw:cpu_policy": "dedicated",
"hw:mem_page_size": "2048"
},
"original_name": "m1.tiny.specs",
"ram": 512,
"swap": 0,
"vcpus": 1
},
"OS-EXT-AZ:availability_zone": "geneva",
"OS-EXT-STS:power_state": 0,
}
]
}
* List Compute Services (GET /os-services): This operation may give
partial constructs for the services with :program:`nova-compute` as
their binary from the non-responsive portion of the
infrastructure. A typical response while listing the compute
services from unreachable parts of the infrastructure would include
only the following keys for the :program:`nova-compute` services
from available information while the other services like the
:program:`nova-conductor` service will be skipped from the result:
- binary: The binary name of the service which would always be
``nova-compute``.
- host: The name of the host running the service.
- status: The status of the service which will be "UNKNOWN".
A sample response for a GET /servers request that includes two
compute services from unreachable parts of the infrastructure and
other services from a healthy one are shown below.
Response::
{
"services": [
{
"binary": "nova-compute",
"host": "host1",
"status": "UNKNOWN"
},
{
"binary": "nova-compute",
"host": "host2",
"status": "UNKNOWN"
},
{
"id": 1,
"binary": "nova-scheduler",
"disabled_reason": "test1",
"host": "host3",
"state": "up",
"status": "disabled",
"updated_at": "2012-10-29T13:42:02.000000",
"forced_down": false,
"zone": "internal"
},
{
"id": 2,
"binary": "nova-compute",
"disabled_reason": "test2",
"host": "host4",
"state": "up",
"status": "disabled",
"updated_at": "2012-10-29T13:42:05.000000",
"forced_down": false,
"zone": "nova"
}
]
}

1
api-guide/source/index.rst
View File

@ -85,6 +85,7 @@ Contents
paginated_collections
polling_changes
request_and_response_formats
down_cells
.. toctree::
:hidden:

5
api-guide/source/server_concepts.rst
View File

@ -77,8 +77,9 @@ server status is one of the following values:
Suspending a server is similar to placing a device in hibernation;
memory and vCPUs become available to create other servers.
- ``UNKNOWN``: The state of the server is unknown. Contact your cloud
provider.
- ``UNKNOWN``: The state of the server is unknown. It could be because a part
of the infrastructure is temporarily down (see :doc:`down_cells`
for more information). Contact your cloud provider.
- ``VERIFY_RESIZE``: System is awaiting confirmation that the server is
operational after a move or resize.

8
api-ref/source/os-services.inc
View File

@ -21,6 +21,14 @@ Lists all running Compute services.
Provides details why any services were disabled.
.. note:: Starting with microversion 2.69 if service details cannot be loaded
due to a transient condition in the deployment like infrastructure failure,
the response body for those unavailable compute services in the down cells
will be missing keys. See `handling down cells
<https://developer.openstack.org/api-guide/compute/down_cells.html>`__
section of the Compute API guide for more information on the keys that
would be returned in the partial constructs.
Normal response codes: 200
Error response codes: unauthorized(401), forbidden(403)

24
api-ref/source/servers.inc
View File

@ -175,6 +175,14 @@ whitelist will be silently ignored.
- For admin user, whitelist includes all filter keys mentioned in
:ref:`list-server-request` Section.
.. note:: Starting with microversion 2.69 if server details cannot be loaded
due to a transient condition in the deployment like infrastructure failure,
the response body for those unavailable servers will be missing keys. See
`handling down cells
<https://developer.openstack.org/api-guide/compute/down_cells.html>`__
section of the Compute API guide for more information on the keys that
would be returned in the partial constructs.
Normal response codes: 200
Error response codes: badRequest(400), unauthorized(401),
@ -506,6 +514,14 @@ OS-SRV-USG:terminated_at attributes.
HostId is unique per account and is not globally unique.
.. note:: Starting with microversion 2.69 if server details cannot be loaded
due to a transient condition in the deployment like infrastructure failure,
the response body for those unavailable servers will be missing keys. See
`handling down cells
<https://developer.openstack.org/api-guide/compute/down_cells.html>`__
section of the Compute API guide for more information on the keys that
would be returned in the partial constructs.
Normal response codes: 200
Error response codes: badRequest(400), unauthorized(401),
@ -665,6 +681,14 @@ HostId is unique per account and is not globally unique.
The server must exist.
.. note:: Starting with microversion 2.69 if the server detail cannot be loaded
due to a transient condition in the deployment like infrastructure failure,
the response body for the unavailable server will be missing keys. See
`handling down cells
<http://developer.openstack.org/api-guide/compute/down_cells.html>`__
section of the Compute API guide for more information on the keys that
would be returned in the partial constructs.
Normal response codes: 200
Error response codes: unauthorized(401), forbidden(403),

14
doc/source/user/cells.rst
View File

@ -806,3 +806,17 @@ FAQs
solved by adding a generic by-aggregate filter, which would allow
listing instances on hosts contained within any aggregate,
including one that matches the cell boundaries if so desired.
#. Why are the API responses for ``GET /servers``, ``GET /servers/detail``,
``GET /servers/{server_id}`` and ``GET /os-services`` missing some
information for certain cells at certain times? Why do I see the status as
"UNKNOWN" for the servers in those cells at those times when I run
``openstack server list`` or ``openstack server show``?
Starting from microversion 2.69 the API responses of ``GET /servers``,
``GET /servers/detail``, ``GET /servers/{server_id}`` and
``GET /os-services`` may contain missing keys during down cell situations.
See the `Handling Down Cells
<https://developer.openstack.org/api-guide/compute/down_cells.html>`__
section of the Compute API guide for more information on the partial
constructs.

14
nova/api/openstack/compute/rest_api_version_history.rst
View File

@ -865,3 +865,17 @@ be used to specify cinder ``volume_type`` when creating a server.
----
Remove support for forced live migration and evacuate server actions.
2.69
----
Add support for returning minimal constructs for ``GET /servers``,
``GET /servers/detail``, ``GET /servers/{server_id}`` and ``GET /os-services``
when there is a transient unavailability condition in the deployment like an
infrastructure failure. Starting from this microversion, the responses from the
down part of the infrastructure for the above four requests will have missing
key values to make it more resilient. The response body will only have a
minimal set of information obtained from the available information in the API
database for the down cells. See `handling down cells
<https://developer.openstack.org/api-guide/compute/down_cells.html>`__ for
more information.

4
nova/conf/api.py
View File

@ -340,7 +340,9 @@ True.
Note that from API microversion 2.69 there could be transient conditions in the
deployment where certain records are not available and the results could be
partial for certain requests containing those records. In those cases this
option will be ignored.
option will be ignored. See "Handling Down Cells" section of the Compute API
guide (https://developer.openstack.org/api-guide/compute/down_cells.html) for
more information.
"""),
]

12
releasenotes/notes/bp-handling-down-cell-10f76145d767300c.yaml Normal file
View File

@ -0,0 +1,12 @@
---
features:
- |
From microversion 2.69 the responses of ``GET /servers``,
``GET /servers/detail``, ``GET /servers/{server_id}`` and
``GET /os-services`` will contain missing keys during down cell situations
because of adding support for returning minimal constructs based on the
available information from the API database for those records in the
down cells. See `Handling Down Cells`_ for more information on the missing
keys.
.. _Handling Down Cells: https://developer.openstack.org/api-guide/compute/down_cells.html