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 Understanding Repository Configuration of Apache Archiva
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 Maria Odea Ching
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 13 Nov 2007
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Understanding Repository Configuration of Apache Archiva

~~TODO: revise more as suggested by Jeff in the dev list

  Archiva has two types of repository configuration: managed repository and remote repository. 
  
* Managed Repository

  A managed repository is a repository which resides locally to the server where Archiva is running. It could serve as a 
  proxy repository, an internal deployment repository or a local mirror repository. 
  
  Managed repository fields:  
  
  * <identifier> - the id of the repository. This must be unique.
  
  * <name> - the name of the repository.
  
  * <directory> - the location of the repository. If the path specified does not exist, Archiva will create the missing 
  	 directories.
  	
  * <type> - the repository layout (maven 2 or maven 1)
  
  * <cron> - the {{{http://quartz.sourceforge.net/javadoc/org/quartz/CronTrigger.html}cron schedule}} when repository scanning will be executed.
  
  * <repository purge by days older> - the first option for repository purge. Archiva will check how old the artifact is
  	 and if it is older than the set number of days in this field, then the artifact will be deleted respecting the retention
  	 count (see #7) of course. In order to disable the purge by number of days old and set Archiva to purge by retention count, just set the 
  	 repository purge field to 0. The maximum number of days which can be set here is 1000. See the Repository Purge section
     below for more details. 
  	
  * <repository purge by retention count> - the second option for repository purge. When running the repository purge, Archiva
  	 will retain only the number of artifacts set for this field for a specific snapshot version. See the Repository Purge section
     below for more details. 
  	
  * <releases included> - specifies whether there are released artifacts in the repository.
  
  * <snapshots included> - specifies whether there are snapshot artifacts in the repository.
  
  * <scannable> - specifies whether the repository can be scanned, meaning it is a local repository which can be indexed, browsed,
      purged, etc.
  
  * <delete released snapshots> - specifies whether to remove those snapshot artifacts which already has release versions
  	  of it in the repository during repository purge. 
  
  []
  
  Each repository has its own Webdav url. This allows the user to browse and access the repository via webdav. The url has the
  following format: 
 
+----+  
http://[URL TO ARCHIVA]/repository/[REPOSITORY ID] (e.g. http://localhost:8080/archiva/repository/releases).
+----+

  A pom snippet is also available for each repository. The \<distributionManagement\> section can be copied and pasted into a 
  project's pom to specify that the project will be deployed in that managed repository. The \<repositories\> section on the
  other hand, can be copied and pasted to a project's pom.xml or to Maven's settings.xml to tell Maven to get artifacts
  from the managed repository when building the project. 
  
* Remote Repository

  A remote repository is a repository which resides remotely. These repositories are usually the proxied repositories. See
  Proxy Connectors on how to proxy a repository.

  Remote repository fields:  
  
  * <identifier> - the id of the remote repository.
  
  * <name> - the name of the remote repository.
  
  * <url> - the url of the remote repository. It is also possible to use a 'file://' url to proxy a local repository. Be careful that if this local repository is a managed repository of archiva which has some proxies connectors, those ones won't be triggered. 
  
  * <username> - the username (if authentication is needed) to be used to access the repository.
  
  * <password> - the password (if authentication is needed) to be used to access the repository.
  
  * <type> - the layout (maven 2 or maven 1) of the remote repository.  
  
* Scanning a Repository
 
  Repository scan can be executed on schedule or it can be explicitly executed by clicking the 'Scan Repository Now' button in 
  the repositories page. For every artifact found by the repository scanner, processing is done on this artifact by different
  consumers. Examples of the processing done are: indexing, repository purge and database update. Details about consumers are 
  available in the {{{consumers.html} Consumers}} page.

* Repository Purge

  Repository purge is the process of cleaning up the repository of old snapshots. When deploying a snapshot to a repository, 
  Maven deploys the project/artifact with a timestamped version. Doing daily/nightly builds of the project then tends to bloat 
  the repository. What if the artifact is large? Then disk space will definitely be a problem. That's where Archiva's repository 
  purge feature comes in. Given a criteria to use -- by the number of days old and by retention count, it would clean up the 
  repository by removing old snapshots.
  
  Let's take a look at different behaviours for repository purge using the following scenario:

+----+
Artifacts in the repository:

../artifact-x/2.0-SNAPSHOT/artifact-x-20061118.060401-2.jar
../artifact-x/2.0-SNAPSHOT/artifact-x-20061118.060401-2.pom
../artifact-x/2.0-SNAPSHOT/artifact-x-20070113.034619-3.jar
../artifact-x/2.0-SNAPSHOT/artifact-x-20070113.034619-3.pom
../artifact-x/2.0-SNAPSHOT/artifact-x-20070203.028902-4.jar
../artifact-x/2.0-SNAPSHOT/artifact-x-20070203.028902-4.pom
+----+
  
  [[1]] Repository Purge By Days Older
  
  Using this criteria for the purge, Archiva will check how old an artifact is and if it is older than the set value in the
  repository purge by days older field, then the artifact will be deleted respecting the retention count of course.
       
  If repository purge by days older is set to 100 days (with repository purge by retention count field set to 1), 
  and the current date is let's say 03-01-2007, given the scenario above.. the following artifacts will be retained:
  artifact-x-20070113.034619-3.jar, artifact-x-20070113.034619-3.pom, artifact-x-20070203.028902-4.jar and 
  artifact-x-20070203.028902-4.pom. It is clear in the version timestamps that these 4 artifacts are not more than 
  100 days old from the current date (which is 03-01-2007 in our example) so they are all retained. In this case
  the retention count doesn't have any effect since the priority is the age of the artifact. 
  
  Now, if the repository purge by days older is set to 30 days (with repository purge by retention count field still 
  set to 1) and the current date is still 03-01-2007, then given the same scenario above.. only the following artifacts
  will be retained: artifact-x-20070203.028902-4.jar and artifact-x-20070203.028902-4.pom. In this case, we can see 
  that the retained artifacts are still not older by the number of days set in the repository purge by days older field
  and the retention count is still met.
	  	
  Now, let's set the repository purge by days older to 10 days (with repository purge by retention count field still 
  set to 1) and the current date is still 03-01-2007, then still given the same repository contents above.. the 
  following artifacts will still be retained: artifact-x-20070203.028902-4.jar and artifact-x-20070203.028902-4.pom.
  It is clear from the version timestamps that the artifacts ARE MORE THAN the repository purge by days older value, 
  which is 10 days. Why is it still retained? Recall the value of the repository purge by retention count -- 1 :)
  This ensures that there is ALWAYS 1 artifact timestamped version retained for every unique version snapshot directory 
  of an artifact. 	  	
	  	
  [[2]] Repository Purge By Retention Count
    
  If the repository purge by retention count field is set to 2, then only the artifacts artifact-x-20070113.034619-3.jar,
  artifact-x-20070113.034619-3.pom, artifact-x-20070203.028902-4.jar and artifact-x-20070203.028902-4.pom will be retained 
  in the repository. The oldest snapshots will be deleted maintaining only a number of snapshots equivalent to the set 
  retention count. 

* Scanning a Database

  Another scanning process also occurs in Archiva, the database scanning. Same as with repository scanning,
  it can also be executed on schedule or explicitly. This can be configured in the 'Database' page, via the 'Database -
  Unprocessed Artifacts Scanning' section.

  It is essential that the database scan occur after the repo scan as this is where the pom information of the artifacts in
  the database will be processed by the consumers and in turn, added to the database (as ArchivaProjectModel objects). For
  more details about the different database consumers, please see the {{{consumers.html} Consumers}} page.