Pulp

Story #3295

Updated by amacdona@redhat.com almost 7 years ago

Tasks that create new Publications have to write to pulpcore tables in transactions, mark the set up a working directory, finalize publication complete, and clean up the database if the task fails. All of this should be handled by a context manager that is a part of the plugin API. 


 h2. Proposal: Wrapper for the Publication object in the plugin API 

 The pulpcore model for Publication will be removed from the plugin API, so the wrapper will be the only supported way for plugin writers to create new Publications, and must be performed only in celery tasks.  

 The Publication wrapper:  
 * can be used as a context manager that creates Publications.  
 * uses transactions to create a new publication and update related tables 
 * handles failure scenarios by cleaning up incomplete work 
 * can be used to retrieve content from a Publication.repository_version.content() 
 * can create new PublishedMetadata objects from files 
 * can create new PublishedArtifacts from Artifacts or RemoteArtifacts 
 * Can only publish Metadata and Artifacts if complete=False 
 * Can only publish if run in a task 
 * has exclusive control of the Publication.complete flag 


 h3. example usage 

 Create a new Publication. Plugin writers can use this object to create and write metadata, and can be used to create PublishedMetadata. 

 <pre><code class="python"> 

 with Publication.create(repository_version) as publication: 
     # If Publication requires new metadata, generate and write it. 
     metadata_path = some_function_to_write_metadata(publication) 
     # Create and save PublishedMetadata object 
     publication.publish_metadata(metadata_path) 
     # Create and save PublishedArtifact  
     publication.publish_artifact(artifact) 


 </code></pre> 


 The wrapper object can also be used to access the Publication model layer, which replaces the use of plugin.models.Publication.objects.get() with: 

 <pre><code class="python"> 

 latest_publication = Publication.latest(repository) 
 some_publication = Publication.get(repository_version=repository_version) 

 for content in publication.content() 
     # This is a shortcut for publication._model.repository_version.content() 
     do_something(content) 

 </code></pre> 

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