drubs install fails on the second and repeated builds due to the command 'chmod -R u+w ...sites/default': operation not permitted
On remote hosts where this was observed, the ownership of subdirectories of sites/default/files:
drwxrwxr-x. 3 apache apache 4096 Apr 1 09:44 bootstrap
-rw-r--r--. 1 jenkins www-users 3434 Apr 1 09:44 failed.csv
drwxrwxr-x. 2 jenkins www-users 4096 Apr 1 09:43 notices
drwxrwxr-x. 3 jenkins www-users 4096 Apr 1 09:42 private
drwxrwxr-x. 2 jenkins www-users 4096 Apr 1 09:41 styles
-rw-r--r--. 1 jenkins www-users 49138 Apr 1 09:44 success.csv
The locations which could not be chmod'ed look like 'bootstrap' above - which makes sense. In this case the jenkins user is a member of the apache group, however that does not give jenkins (the user which drubs is logging in as) the permission to chmod the offending directories (such as 'bootstrap').
In drubs, removing the "-R" from the offending command, near or at here: https://github.com/komlenic/drubs/blob/master/drubs/node.py#L233 ...seems to correct this issue, and the directories, regardless of ownership by apache or jenkins are able to be removed on subsequent builds.
This seems likely to be the only fix required - especially considering that predecessor code to drubs did not include the '-R' flag.