Models

CMP is a Django application, and its data is stored in a PostgreSQL database via Django’s object-relational mapper. Change objects through the ORM rather than in SQL: CMP’s business logic runs on create and change, and a direct UPDATE skips it.

Explore the models

• Shell Plus opens a Python shell with every model imported, and you can use tab completion to list an object’s fields and methods. Getting comfortable with it pays off when you start writing plugins.
• Use Django ORM covers querying and updating objects from a plugin, including key query patterns.
• Admin > API Browser lists the objects and operations that CMP exposes via the REST API, which is a useful cross-check for names and relationships.

Generate a database diagram

CMP ships with the graph_models management command, which renders an entity-relationship diagram for one or more Django apps. The CMP schema is too large to fit in a single image; generate one app at a time.

Install the diagram tools

Rendering to an image needs Graphviz and PyDotPlus. Install them as the root user on the CMP appliance.

sudo su -
yum install -y graphviz
pip install pydotplus

Generate the diagram

Start by determining which app owns your target model. An app label is the name of the model’s package: Server lives in infrastructure, ResourceHandler in resourcehandlers, OSBuild in externalcontent. In Shell Plus, Server._meta.app_label returns the label for any model.

Then generate the file. The output format follows the file extension you give --output. This example writes the infrastructure app’s schema to infrastructure.pdf in the current directory. Copy the file from the appliance with scp or a similar tool to view it.

/opt/cloudbolt/manage.py graph_models -t original --output infrastructure.pdf infrastructure

Pass several app labels to draw them on one diagram.