Static Data Source Configuration

https://blueprints.launchpad.net/vitrage/+spec/static-datasource-config-format

The configuration of static data source has a lot in common with entity and relationships definition in evaluator template. This blueprint proposes a refactoring to reuse the template format and parsing methods in static data source. By doing so, we may reduce the work in maintenance and bring in new features more easily.

Problem description

Currently the configuration of static data source use a dedicated format, which has a lot of overlapping with the evaluator templates.

In static configuration, there are entities and their relationships

- entities
  - {entity}
  - {entity}

In each entity

- name:
  id:
  relationship:
    - {relationship}
    - {relationship}

In evaluator templates we define: entities, relationship and scenarios. Each scenario has a condition and actions.

- definitions
  - entities
    - {entity}
    - {entity}
  - relationships
    - {relationship}
    - {relationship}

Though serving different purpose, they both

1. Describe entities and relationships

2. Use a dedicated key (id/template_id) to reference the items

3. Include a source entity and target entity in relationship

The main differences between the two are

• Evaluator templates defines a topology and scenarios based on it

• Static config defines a topology and adds it to the graph

We may define the static configuration using the same format as the evaluator templates. And then simulate an entity discovery from the same file.

By reusing the template parsing engine and workflow, we may reduce the work in maintenance and bring in new features more easily.

Proposed change

Refactoring the static data source template and use the same parser as in evaluator template.

Discover entities from the static data source template.

For backward compatibility, static data source will take over the control of the default configuration folder /etc/vitrage/static_datasource which was used by static physical datasource.

Both legacy format and new format will be placed in the same folder. static datasource parse the file and check the existence of meta to decide which engine to use. If not found, proxy the job to static physical datasource and print a deprecation warning.

Static physical datasource will be disabled by default and throws exception if running standalone.

Alternatives

Fix the issues found in static data source without refactoring the format. This will keep best back-compatibility but will cause redundant work with scenario evaluator.

Data model impact

None

REST API impact

None

Versioning impact

• Backward compatibility with old format will be kept.

• This introduces a new feature and a minor version incremental is required.

Other end user impact

New format of static data source configuration should be applied by the end user.

Deployer impact

Old parser will be kept but a deprecated warning will be prompt.

Developer impact

None

Horizon impact

None

Implementation

Assignee(s)

Primary assignee:

yujunz

Other contributors:

None

Work Items

• Reuse the parser of evaluator template in static data source configuration.

• Discover entities from the configuration.

• Add deprecated warning on old format.

Dependencies

None

Testing

The changes shall be covered by new unit test.

Documentation Impact

New format of the template shall be documented.

References

None