Catalog

Brooklyn provides a catalog, which is a persisted collection of versioned blueprints. These can be deployed directly or referenced by other blueprints. Blueprints in the catalog can be deployed via the Brooklyn REST API, or from the web-console’s “Catalog” tab of the “Create Application” wizard dialog box.

Catalog Items

An item to be added to the catalog is defined in YAML. This follows the syntax of a YAML blueprint with an addition brooklyn.catalog section giving the metadata needed to register the blueprint in the catalog:

brooklyn.catalog:
  id: my-MySQL
  version: 1.0
  iconUrl: classpath://mysql.png
  description: MySql is an open source relational database management system (RDBMS)
  libraries:
    - url: http://example.com/path/to/my-dependency-1.2.3.jar
    - url: http://example.com/path/to/my-other-dependency-4.5.6.jar

services:
- type: brooklyn.entity.database.mysql.MySqlNode

To explain the brooklyn.catalog fields:

  • The id: MySQL line specifies a unique ID used by Brooklyn to identify the catalog item. Other blueprints can reference the catalog item using this id.
  • The version: 1.0 line provides a unique version for the blueprint. Note that this is typically not the version of the software being installed (in this case MySQL).
  • The iconUrl: classpath://... is an optional line where an icon can be specified for use with the item (in the “Add Application” dialog and elsewhere). Note that classpath URLs cannot refer to items in the OSGi bundle (to prevent requiring all OSGi bundles to be loaded at launch); use the server supplying the OSGi bundles or the conf folder of the Brooklyn distro instead.
  • The description: ... line, also optional, allows supplying a free-format description of the blueprint.

The libraries section references OSGi bundles required for the blueprint. It can be omitted if everything required by the blueprint is already on the Brooklyn classpath. These URL’s should be to stable OSGi bundles; if the contents at any of these URLs changes, the behaviour of the blueprint may change whenever a bundle is reloaded in a Brooklyn server, and if entities have been deployed against that version, their behavior may change in subtle or potentially incompatible ways. To avoid this situation, it is highly recommended to use OSGi version stamps as part of the URL.

To reference a catalog item in another blueprint, simply reference its ID and optionally its version number. For example: 

services:
- type: my-MySQL:1.0

Adding to the Catalog

To add a catalog item to the catalog, POST the YAML file to /v1/catalog endpoint in Brooklyn’s REST API. To do this using curl:

curl http://127.0.0.1:8081/v1/catalog --data-binary @/path/to/mysql-catalog.yaml

Deleting from the Catalog

You can delete a versioned item from the catalog using the same endpoint at the REST API. For example, to delete the item with id my-MySQL and version 1.0 with curl:

curl -X DELETE http://127.0.0.1:8081/v1/catalog/entities/MySQL/1.0

Note: Catalog items should not be deleted if there are running apps which were created using the same item. During rebinding the catalog item is used to reconstruct the entity.

Versioning

Version numbers follow the OSGi convention. This can have a major, minor, micro and qualifier part. For example, 1.0. 1.0.1 or 1.0.1-20150101.

The combination of id:version strings must be unique across the catalog. It is an error to deploy the same version of an existing item: to update a blueprint, it is recommended to increase its version number; alternatively in some cases it is permitted to delete an id:version instance and then re-deploy. If no version is specified, re-deploying will automatically increment an internal version number for the catalog item.

When referencing a blueprint, if a version number is not specified the latest non-snapshot version will be loaded when an entity is instantiated.

Special Requirements for the “Create Application” Wizard Dialog

For a blueprint in the catalog to be accessible via the ‘Create Application’ dialog, it must be an Application (i.e. the entity at the root of the blueprint must implement brooklyn.entity.Application). In contrast, if a YAML blueprint is deployed direct via the REST API, then this is not necessary.

For example, the MySql catalog item defined previously could be re-written to use a brooklyn.entity.basic.BasicApplication, because no application-specific logic is required other than to pass-through the start and stop commands. the MySqlNode is added as a child of the BasicApplication.

brooklyn.catalog:
  id: my-MySQL
  version: 1.0
  iconUrl: classpath://mysql.png
  description: MySql is an open source relational database management system (RDBMS)

name: MySQL Database
services:
- type: brooklyn.entity.basic.BasicApplication
  brooklyn.children:
  - type: brooklyn.entity.database.mysql.MySqlNode

When added to the catalog via the HTTP POST command, the blueprint will appear in the ‘Create Application’ dialog as shown here:

MySQL in Brooklyn Catalog

When deploying a new version of a blueprint, the catalog will show both the previous and the new versions of the blueprint. You may wish to delete the older version, assuming no applications currently running are using that old version.