Offlining maven: how to set up the p2 cache?

["Thibault, Daniel" <Da...@drdc-rddc.gc.ca>]

   I have these two projects that need to be compiled offline.  I thought I would first compile them on-line and then transplant the ~/.m2/repository to the offline system.  However, something isn't quite right.  I'm using Apache Maven 3.3.9 and Java 1.8.0_45.

   The two projects (when run with 'mvn --offline') both give a failure along the lines of:

[INFO] Adding repository http://download.eclipse.org/tools/cdt/releases/8.8
[ERROR] Failed to resolve target definition <...>.target: Failed to load p2 metadata repository from location http://download.eclipse.org/tools/cdt/releases/8.8/: Repository system is offline and no local cache available for http://download.eclipse.org/tools/cdt/releases/8.8 -> [Help 1]

   Isn't the p2 cache in ~/.m2/repository/p2 ?

   Strangely, the two projects behave differently.

   For one, building offline fails as described above while building online fetches 15 compositeContent.xml, content.jar, content.xml.xz and p2.index from download.eclipse.org before using the cache and completing normally.

   For the other, the first offline run caused a Java exception (same error as above, somehow not handled).  I then ran it online, successfully (same behaviour as the other project).  But running it offline now succeeds as well!

   What is the established procedure for setting up the m2 and p2 caches in order to ensure maven builds succeed offline?

Daniel U. Thibault, M.Sc.²

Informaticien scientifique, CME-PSC, Centre de recherches de Valcartier
Recherche et développement pour la défense Canada / Gouvernement du Canada
daniel.thibault@drdc-rddc.gc.ca<ma...@drdc-rddc.gc.ca> / Tél: 418-844-4000x4245 Téléc: 418-844-4538
daniel.thibault@forces.gc.ca<ma...@forces.gc.ca> / Tél: 418-844-4000x4245 Téléc: 418-844-4538

Computer Scientist, MCCS-SPC, Valcartier Research Centre
Defence Research and Development Canada / Government of Canada
daniel.thibault@drdc-rddc.gc.ca<ma...@drdc-rddc.gc.ca> / Tel: 418-844-4000x4245 Fax: 418-844-4538
daniel.thibault@forces.gc.ca<ma...@forces.gc.ca> / Tel: 418-844-4000x4245 Fax: 418-844-4538

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