Section provides
This is a high level instruction to broadcast to the other components that after this component has been deployed, there is a new capability (or capabilities).
Capability is an arbitrary string. This string will be recognized by the other component in requires section.
Access Provides from Component
When component wants to check capabilities provided by environment or by other component. It can use:
- Well-known environment variable
HUB_PROVIDES- same format as above. - Well-known parameter
hub.provides- whitespace separated list of capabilities
Where parameter is a good choice for deploy.sh or pre-deploy.sh, or deployment hooks scripts. While parameter can be checked for instance by gotemplate
Best Practice
Both provides and requires component maintainers agree on the exact capability string. They also agree on well-defined outputs which component will provide together with the capability. In the other words requires and provides defines mutual contract between components on what parameters to expect from each other.
For instance, when component provides capability bucket it should also provide following outputs:
outputs:
- name: bucket.endpoint
- name: bucket.region
- name: bucket.name
- name: bucket.accessKey
- name: bucket.secretKey
This will make such components as minio and gsbucket virtually interchangeable.
There are a lot of parameters. You don't need all of them to output. Some parameters can be consumed by the input. However, component that will require either minio or gsbucket, it may expect these parameters will be provided.