Create dynamic pollster feature

The dynamic pollster feature allows system administrators to
create/update pollsters on the fly (without changing code). The system
reads YAML configures that are found in ``pollsters_definitions_dirs``,
which has the default at ``/etc/ceilometer/pollsters.d``. Each YAML file
in the dynamic pollster feature can use the following attributes to
define a dynamic pollster:

* ``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. 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. As an example, for magnum, one can use the following values:
```
  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.
```
  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:
```
  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_mapping``: 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``.

Change-Id: I5f0614518a9e304b86b74aa5bb0f9667d2a3a787
Signed-off-by: Rafael Weingärtner <rafael@apache.org>

1 files changed, 6 insertions, 0 deletions

diff --git a/.gitignore b/.gitignore
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--- a/.gitignore
+++ b/.gitignore
@@ -23,3 +23,9 @@ releasenotes/build
 
 #IntelJ Idea
 .idea/
+
+#venv
+venv/
+
+#Pyenv files
+.python-version