How to define a custom capability¶
In Section How to define a ConnectsTo relationship between service catalogs, we used the default capability tosca.capabilities.Endpoint.Database. The capability has the some default properties: port, protocol.
Figure 1. Default properties of an endpoint capability¶
The following section shows how to define custom capabilities.
Steps¶
Step 1. Define a custom capability¶
To add more properties to a capability, or to set a default value to a capability, we define a custom one as follows:
capability_types:
# define a custom capability
tosca.capabilities.Endpoint.Database.Mongo:
derived_from: tosca.capabilities.Endpoint.Database
properties:
port:
type: integer
default: 27017
Here, the custom capability tosca.capabilities.Endpoint.Database.Mongo inherits all properties from the parent type tosca.capabilities.Endpoint.Database and set the port property to the default value 27017.
Step 2. Update the target node to have the new capability¶
node_types:
otc.nodes.SoftwareComponent.MongoDB:
...
capabilities:
mongo_db:
type: tosca.capabilities.Endpoint.Database.Mongo
Step 3. Update the source node to require a target node with the new capability¶
node_types:
otc.nodes.WebApplication.Nodecellar:
derived_from: tosca.nodes.WebApplication
...
requirements:
- mongo_db:
# nodecellar requires to a node that has the capability Endpoint.Database.Mongo
capability: tosca.capabilities.Endpoint.Database.Mongo
...