ceilometer/doc/source/admin/telemetry-dynamic-pollster.rst
Rafael Weingärtner 549df53f9c Statement about complex object handling in the Dynamic pollster documentation
Change-Id: Iae1b317db25a8c3b6e9f8400c572cc653367d4c9
2020-09-04 23:11:21 -03:00

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.. _telemetry_dynamic_pollster:
Introduction to dynamic pollster subsystem
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The dynamic pollster feature allows system administrators to
create/update REST API pollsters on the fly (without changing code).
The system reads YAML configures that are found in
``pollsters_definitions_dirs`` parameter, which has the default at
``/etc/ceilometer/pollsters.d``. Operators can use a single file per
dynamic pollster or multiple dynamic pollsters per file.
Current limitations of the dynamic pollster system
--------------------------------------------------
Currently, the following types of APIs are not supported by the
dynamic pollster system:
* Tenant APIs: Tenant APIs are the ones that need to be polled in a tenant
fashion. This feature is "a nice" to have, but is currently not
implemented.
The dynamic pollsters system configuration (for OpenStack APIs)
---------------------------------------------------------------
Each YAML file in the dynamic pollster feature can use the following
attributes to define a dynamic pollster:
.. warning::
Caution: Ceilometer does not accept complex value data structure for
``value`` and ``metadata`` configurations. Therefore, if you are extracting
a complex data structure (Object, list, map, or others), you can take
advantage of the ``Operations on extracted attributes`` feature to transform
the object into a simple value (string or number)
* ``name``: mandatory field. It specifies the name/key of the dynamic
pollster. For instance, a pollster for magnum can use the name
``dynamic.magnum.cluster``;
* ``sample_type``: mandatory field; it defines the sample type. It must
be one of the values: ``gauge``, ``delta``, ``cumulative``;
* ``unit``: mandatory field; defines the unit of the metric that is
being collected. For magnum, for instance, one can use ``cluster`` as
the unit or some other meaningful String value;
* ``value_attribute``: mandatory attribute; defines the attribute in the
JSON response from the URL of the component being polled. We also accept
nested values dictionaries. To use a nested value one can simply use
``attribute1.attribute2.<asMuchAsNeeded>.lastattribute``. It is also
possible to reference the sample itself using ``"." (dot)``; the self
reference of the sample is interesting in cases when the attribute might
not exist. Therefore, together with the operations options, one can first
check if it exist before retrieving it (example:
``". | value['some_field'] if 'some_field' in value else ''"``).
In our magnum example, we can use ``status`` as the value attribute;
* ``endpoint_type``: mandatory field; defines the endpoint type that is
used to discover the base URL of the component to be monitored; for
magnum, one can use ``container-infra``. Other values are accepted such
as ``volume`` for cinder endpoints, ``object-store`` for swift, and so
on;
* ``url_path``: mandatory attribute. It defines the path of the request
that we execute on the endpoint to gather data. For example, to gather
data from magnum, one can use ``v1/clusters/detail``;
* ``metadata_fields``: optional field. It is a list of all fields that
the response of the request executed with ``url_path`` that we want to
retrieve. To use a nested value one can simply use
``attribute1.attribute2.<asMuchAsNeeded>.lastattribute``. As an example,
for magnum, one can use the following values:
.. code-block:: yaml
metadata_fields:
- "labels"
- "updated_at"
- "keypair"
- "master_flavor_id"
- "api_address"
- "master_addresses"
- "node_count"
- "docker_volume_size"
- "master_count"
- "node_addresses"
- "status_reason"
- "coe_version"
- "cluster_template_id"
- "name"
- "stack_id"
- "created_at"
- "discovery_url"
- "container_version"
* ``skip_sample_values``: optional field. It defines the values that
might come in the ``value_attribute`` that we want to ignore. For
magnun, one could for instance, ignore some of the status it has for
clusters. Therefore, data is not gathered for clusters in the defined
status.
.. code-block:: yaml
skip_sample_values:
- "CREATE_FAILED"
- "DELETE_FAILED"
* ``value_mapping``: optional attribute. It defines a mapping for the
values that the dynamic pollster is handling. This is the actual value
that is sent to Gnocchi or other backends. If there is no mapping
specified, we will use the raw value that is obtained with the use of
``value_attribute``. An example for magnum, one can use:
.. code-block:: yaml
value_mapping:
CREATE_IN_PROGRESS: "0"
CREATE_FAILED: "1"
CREATE_COMPLETE: "2"
UPDATE_IN_PROGRESS: "3"
UPDATE_FAILED: "4"
UPDATE_COMPLETE: "5"
DELETE_IN_PROGRESS: "6"
DELETE_FAILED: "7"
DELETE_COMPLETE: "8"
RESUME_COMPLETE: "9"
RESUME_FAILED: "10"
RESTORE_COMPLETE: "11"
ROLLBACK_IN_PROGRESS: "12"
ROLLBACK_FAILED: "13"
ROLLBACK_COMPLETE: "14"
SNAPSHOT_COMPLETE: "15"
CHECK_COMPLETE: "16"
ADOPT_COMPLETE: "17"
* ``default_value``: optional parameter. The default value for
the value mapping in case the variable value receives data that is not
mapped to something in the ``value_mapping`` configuration. This
attribute is only used when ``value_mapping`` is defined. Moreover, it
has a default of ``-1``.
* ``metadata_mapping``: optional parameter. The map used to create new
metadata fields. The key is a metadata name that exists in the response
of the request we make, and the value of this map is the new desired
metadata field that will be created with the content of the metadata that
we are mapping. The ``metadata_mapping`` can be created as follows:
.. code-block:: yaml
metadata_mapping:
name: "display_name"
some_attribute: "new_attribute_name"
* ``preserve_mapped_metadata``: optional parameter. It indicates if we
preserve the old metadata name when it gets mapped to a new one.
The default value is ``True``.
* ``response_entries_key``: optional parameter. This value is used to define
the "key" of the response that will be used to look-up the entries used in
the dynamic pollster processing. If no ``response_entries_key`` is informed
by the operator, we will use the first we find. Moreover, if the response
contains a list, instead of an object where one of its attributes is a list
of entries, we use the list directly. Therefore, this option will be
ignored when the API is returning the list/array of entries to be processed
directly. We also accept nested values dictionaries. To use a nested value
one can simply use ``attribute1.attribute2.<asMuchAsNeeded>.lastattribute``
* ``user_id_attribute``: optional parameter. The default value is ``user_id``.
The name of the attribute in the entries that are processed from
``response_entries_key`` elements that will be mapped to ``user_id``
attribute that is sent to Gnocchi.
* ``project_id_attribute``: optional parameter. The default value is
``project_id``. The name of the attribute in the entries that are
processed from ``response_entries_key`` elements that will be mapped to
``project_id`` attribute that is sent to Gnocchi.
* ``resource_id_attribute``: optional parameter. The default value is ``id``.
The name of the attribute in the entries that are processed from
``response_entries_key`` elements that will be mapped to ``id`` attribute
that is sent to Gnocchi.
* ``headers``: optional parameter. It is a map (similar to the
metadata_mapping) of key and value that can be used to customize the header
of the request that is executed against the URL. This configuration works
for both OpenStack and non-OpenStack dynamic pollster configuration.
.. code-block:: yaml
headers:
"x-openstack-nova-api-version": "2.46"
The complete YAML configuration to gather data from Magnum (that has been used
as an example) is the following:
.. code-block:: yaml
---
- name: "dynamic.magnum.cluster"
sample_type: "gauge"
unit: "cluster"
value_attribute: "status"
endpoint_type: "container-infra"
url_path: "v1/clusters/detail"
metadata_fields:
- "labels"
- "updated_at"
- "keypair"
- "master_flavor_id"
- "api_address"
- "master_addresses"
- "node_count"
- "docker_volume_size"
- "master_count"
- "node_addresses"
- "status_reason"
- "coe_version"
- "cluster_template_id"
- "name"
- "stack_id"
- "created_at"
- "discovery_url"
- "container_version"
value_mapping:
CREATE_IN_PROGRESS: "0"
CREATE_FAILED: "1"
CREATE_COMPLETE: "2"
UPDATE_IN_PROGRESS: "3"
UPDATE_FAILED: "4"
UPDATE_COMPLETE: "5"
DELETE_IN_PROGRESS: "6"
DELETE_FAILED: "7"
DELETE_COMPLETE: "8"
RESUME_COMPLETE: "9"
RESUME_FAILED: "10"
RESTORE_COMPLETE: "11"
ROLLBACK_IN_PROGRESS: "12"
ROLLBACK_FAILED: "13"
ROLLBACK_COMPLETE: "14"
SNAPSHOT_COMPLETE: "15"
CHECK_COMPLETE: "16"
ADOPT_COMPLETE: "17"
We can also replicate and enhance some hardcoded pollsters.
For instance, the pollster to gather VPN connections. Currently,
it is always persisting `1` for all of the VPN connections it finds.
However, the VPN connection can have multiple statuses, and we should
normally only bill for active resources, and not resources on `ERROR`
states. An example to gather VPN connections data is the following
(this is just an example, and one can adapt and configure as he/she
desires):
.. code-block:: yaml
---
- name: "dynamic.network.services.vpn.connection"
sample_type: "gauge"
unit: "ipsec_site_connection"
value_attribute: "status"
endpoint_type: "network"
url_path: "v2.0/vpn/ipsec-site-connections"
metadata_fields:
- "name"
- "vpnservice_id"
- "description"
- "status"
- "peer_address"
value_mapping:
ACTIVE: "1"
metadata_mapping:
name: "display_name"
default_value: 0
The dynamic pollsters system configuration (for non-OpenStack APIs)
-------------------------------------------------------------------
The dynamic pollster system can also be used for non-OpenStack APIs.
to configure non-OpenStack APIs, one can use all but one attribute of
the Dynamic pollster system. The attribute that is not supported is
the ``endpoint_type``. The dynamic pollster system for non-OpenStack APIs
is activated automatically when one uses the configurations ``module``.
The extra parameters (in addition to the original ones) that are available
when using the Non-OpenStack dynamic pollster sub-subsystem are the following:
* ``module``: required parameter. It is the python module name that Ceilometer
has to load to use the authentication object when executing requests against
the API. For instance, if one wants to create a pollster to gather data from
RadosGW, he/she can use the ``awsauth`` python module.
* ``authentication_object``: mandatory parameter. The name of the class that we
can find in the ``module`` that Ceilometer will use as the authentication
object in the request. For instance, when using the ``awsauth`` python module
to gather data from RadosGW, one can use the authentication object as
``S3Auth``.
* ``authentication_parameters``: optional parameter. It is a comma separated
value that will be used to instantiate the ``authentication_object``. For
instance, if we gather data from RadosGW, and we use the ``S3Auth`` class,
the ``authentication_parameters`` can be configured as
``<rados_gw_access_key>, rados_gw_secret_key, rados_gw_host_name``.
* ``barbican_secret_id``: optional parameter. The Barbican secret ID,
from which, Ceilometer can retrieve the comma separated values of the
``authentication_parameters``.
As follows we present an example on how to convert the hard-coded pollster
for `radosgw.api.request` metric to the dynamic pollster model:
.. code-block:: yaml
---
- name: "dynamic.radosgw.api.request"
sample_type: "gauge"
unit: "request"
value_attribute: "total.ops"
url_path: "http://rgw.service.stage.i.ewcs.ch/admin/usage"
module: "awsauth"
authentication_object: "S3Auth"
authentication_parameters: "<access_key>,<secret_key>,<rados_gateway_server>"
user_id_attribute: "user"
project_id_attribute: "user"
resource_id_attribute: "user"
response_entries_key: "summary"
We can take that example a bit further, and instead of gathering the `total
.ops` variable, which counts for all the requests (even the unsuccessful
ones), we can use the `successful_ops`.
.. code-block:: yaml
---
- name: "dynamic.radosgw.api.request.successful_ops"
sample_type: "gauge"
unit: "request"
value_attribute: "total.successful_ops"
url_path: "http://rgw.service.stage.i.ewcs.ch/admin/usage"
module: "awsauth"
authentication_object: "S3Auth"
authentication_parameters: "<access_key>, <secret_key>,<rados_gateway_server>"
user_id_attribute: "user"
project_id_attribute: "user"
resource_id_attribute: "user"
response_entries_key: "summary"
Operations on extracted attributes
----------------------------------
The dynamic pollster system can execute Python operations to transform the
attributes that are extracted from the JSON response that the system handles.
One example of use case is the RadosGW that uses <project_id$project_id> as the
username (which is normally mapped to the Gnocchi resource_id). With this
feature (operations on extracted attributes), one can create configurations in
the dynamic pollster to clean/normalize that variable. It is as simple as
defining `resource_id_attribute: "user | value.split('$')[0].strip()"`
The operations are separated by `|` symbol. The first element of the expression
is the key to be retrieved from the JSON object. The other elements are
operations that can be applied to the `value` variable. The value variable
is the variable we use to hold the data being extracted. The previous
example can be rewritten as:
`resource_id_attribute: "user | value.split ('$') | value[0] | value.strip()"`
As follows we present a complete configuration for a RadosGW dynamic
pollster that is removing the `$` symbol, and getting the first part of the
String.
.. code-block:: yaml
---
- name: "dynamic.radosgw.api.request.successful_ops"
sample_type: "gauge"
unit: "request"
value_attribute: "total.successful_ops"
url_path: "http://rgw.service.stage.i.ewcs.ch/admin/usage"
module: "awsauth"
authentication_object: "S3Auth"
authentication_parameters: "<access_key>,<secret_key>,<rados_gateway_server>"
user_id_attribute: "user | value.split ('$') | value[0]"
project_id_attribute: "user | value.split ('$') | value[0]"
resource_id_attribute: "user | value.split ('$') | value[0]"
response_entries_key: "summary"
The Dynamic pollster configuration options that support this feature are the
following:
* value_attribute
* response_entries_key
* user_id_attribute
* project_id_attribute
* resource_id_attribute
Multi metric dynamic pollsters (handling attribute values with list of objects)
-------------------------------------------------------------------------------
The initial idea for this feature comes from the `categories` fields that we
can find in the `summary` object of the RadosGW API. Each user has a
`categories` attribute in the response; in the `categories` list, we can find
the object that presents in a granular fashion the consumption of different
RadosGW API operations such as GET, PUT, POST, and may others.
As follows we present an example of such a JSON response.
.. code-block:: json
{
"entries": [
{
"buckets": [
{
"bucket": "",
"categories": [
{
"bytes_received": 0,
"bytes_sent": 40,
"category": "list_buckets",
"ops": 2,
"successful_ops": 2
}
],
"epoch": 1572969600,
"owner": "user",
"time": "2019-11-21 00:00:00.000000Z"
},
{
"bucket": "-",
"categories": [
{
"bytes_received": 0,
"bytes_sent": 0,
"category": "get_obj",
"ops": 1,
"successful_ops": 0
}
],
"epoch": 1572969600,
"owner": "someOtherUser",
"time": "2019-11-21 00:00:00.000000Z"
}
]
}
]
"summary": [
{
"categories": [
{
"bytes_received": 0,
"bytes_sent": 0,
"category": "create_bucket",
"ops": 2,
"successful_ops": 2
},
{
"bytes_received": 0,
"bytes_sent": 2120428,
"category": "get_obj",
"ops": 46,
"successful_ops": 46
},
{
"bytes_received": 0,
"bytes_sent": 21484,
"category": "list_bucket",
"ops": 8,
"successful_ops": 8
},
{
"bytes_received": 6889056,
"bytes_sent": 0,
"category": "put_obj",
"ops": 46,
"successful_ops": 46
}
],
"total": {
"bytes_received": 6889056,
"bytes_sent": 2141912,
"ops": 102,
"successful_ops": 102
},
"user": "user"
},
{
"categories": [
{
"bytes_received": 0,
"bytes_sent": 0,
"category": "create_bucket",
"ops": 1,
"successful_ops": 1
},
{
"bytes_received": 0,
"bytes_sent": 0,
"category": "delete_obj",
"ops": 23,
"successful_ops": 23
},
{
"bytes_received": 0,
"bytes_sent": 5371,
"category": "list_bucket",
"ops": 2,
"successful_ops": 2
},
{
"bytes_received": 3444350,
"bytes_sent": 0,
"category": "put_obj",
"ops": 23,
"successful_ops": 23
}
],
"total": {
"bytes_received": 3444350,
"bytes_sent": 5371,
"ops": 49,
"successful_ops": 49
},
"user": "someOtherUser"
}
]
}
In that context, and having in mind that we have APIs with similar data
structures, we developed an extension for the dynamic pollster that enables
multi-metric processing for a single pollster. It works as follows.
The pollster name will contain a placeholder for the variable that
identifies the "submetric". E.g. `dynamic.radosgw.api.request.{category}`.
The placeholder `{category}` indicates the object's attribute that is in the
list of objects that we use to load the sub metric name. Then, we must use a
special notation in the `value_attribute` configuration to indicate that we are
dealing with a list of objects. This is achieved via `[]` (brackets); for
instance, in the `dynamic.radosgw.api.request.{category}`, we can use
`[categories].ops` as the `value_attribute`. This indicates that the value we
retrieve is a list of objects, and when the dynamic pollster processes it, we
want it (the pollster) to load the `ops` value for the sub metrics being
generated.
Examples on how to create multi-metric pollster to handle data from RadosGW API
are presented as follows:
.. code-block:: yaml
---
- name: "dynamic.radosgw.api.request.{category}"
sample_type: "gauge"
unit: "request"
value_attribute: "[categories].ops"
url_path: "http://rgw.service.stage.i.ewcs.ch/admin/usage"
module: "awsauth"
authentication_object: "S3Auth"
authentication_parameters: "<access_key>, <secret_key>,<rados_gateway_server>"
user_id_attribute: "user | value.split('$')[0]"
project_id_attribute: "user | value.split('$') | value[0]"
resource_id_attribute: "user | value.split('$') | value[0]"
response_entries_key: "summary"
- name: "dynamic.radosgw.api.request.successful_ops.{category}"
sample_type: "gauge"
unit: "request"
value_attribute: "[categories].successful_ops"
url_path: "http://rgw.service.stage.i.ewcs.ch/admin/usage"
module: "awsauth"
authentication_object: "S3Auth"
authentication_parameters: "<access_key>, <secret_key>,<rados_gateway_server>"
user_id_attribute: "user | value.split('$')[0]"
project_id_attribute: "user | value.split('$') | value[0]"
resource_id_attribute: "user | value.split('$') | value[0]"
response_entries_key: "summary"
- name: "dynamic.radosgw.api.bytes_sent.{category}"
sample_type: "gauge"
unit: "request"
value_attribute: "[categories].bytes_sent"
url_path: "http://rgw.service.stage.i.ewcs.ch/admin/usage"
module: "awsauth"
authentication_object: "S3Auth"
authentication_parameters: "<access_key>, <secret_key>,<rados_gateway_server>"
user_id_attribute: "user | value.split('$')[0]"
project_id_attribute: "user | value.split('$') | value[0]"
resource_id_attribute: "user | value.split('$') | value[0]"
response_entries_key: "summary"
- name: "dynamic.radosgw.api.bytes_received.{category}"
sample_type: "gauge"
unit: "request"
value_attribute: "[categories].bytes_received"
url_path: "http://rgw.service.stage.i.ewcs.ch/admin/usage"
module: "awsauth"
authentication_object: "S3Auth"
authentication_parameters: "<access_key>, <secret_key>,<rados_gateway_server>"
user_id_attribute: "user | value.split('$')[0]"
project_id_attribute: "user | value.split('$') | value[0]"
resource_id_attribute: "user | value.split('$') | value[0]"
response_entries_key: "summary"
Handling linked API responses
-----------------------------
If the consumed API returns a linked response which contains a link to the next
response set (page), the Dynamic pollsters can be configured to follow these
links and join all linked responses into a single one.
To enable this behavior the operator will need to configure the parameter
`next_sample_url_attribute` that must contain a mapper to the response
attribute that contains the link to the next response page. This parameter also
supports operations like the others `*_attribute` dynamic pollster's
parameters.
Examples on how to create a pollster to handle linked API responses are
presented as follows:
- Example of a simple linked response:
- API response:
.. code-block:: json
{
"server_link": "http://test.com/v1/test-volumes/marker=c3",
"servers": [
{
"volume": [
{
"name": "a",
"tmp": "ra"
}
],
"id": 1,
"name": "a1"
},
{
"volume": [
{
"name": "b",
"tmp": "rb"
}
],
"id": 2,
"name": "b2"
},
{
"volume": [
{
"name": "c",
"tmp": "rc"
}
],
"id": 3,
"name": "c3"
}
]
}
- Pollster configuration:
.. code-block:: yaml
---
- name: "dynamic.linked.response"
sample_type: "gauge"
unit: "request"
value_attribute: "[volume].tmp"
url_path: "v1/test-volumes"
response_entries_key: "servers"
next_sample_url_attribute: "server_link"
- Example of a complex linked response:
- API response:
.. code-block:: json
{
"server_link": [
{
"href": "http://test.com/v1/test-volumes/marker=c3",
"rel": "next"
},
{
"href": "http://test.com/v1/test-volumes/marker=b1",
"rel": "prev"
}
],
"servers": [
{
"volume": [
{
"name": "a",
"tmp": "ra"
}
],
"id": 1,
"name": "a1"
},
{
"volume": [
{
"name": "b",
"tmp": "rb"
}
],
"id": 2,
"name": "b2"
},
{
"volume": [
{
"name": "c",
"tmp": "rc"
}
],
"id": 3,
"name": "c3"
}
]
}
- Pollster configuration:
.. code-block:: yaml
---
- name: "dynamic.linked.response"
sample_type: "gauge"
unit: "request"
value_attribute: "[volume].tmp"
url_path: "v1/test-volumes"
response_entries_key: "servers"
next_sample_url_attribute: "server_link | filter(lambda v: v.get('rel') == 'next', value) | list(value) | value[0] | value.get('href')"