Upgrade Nexus repository manager on repo.deegree.org

[tfr42]

Nexus on repo.deegree.org needs an update.
Requires:

• backup of Nexus config
• install using bundle
• create systemd service
• remove obsolete tomcat instance

Current configuration is in /usr/local/tomcat/nexus/webapps/ROOT/WEB-INF/plexus.properties
New configuration: ${install_dir}/conf/nexus.properties

Download older versions from

• https://help.sonatype.com/repomanager2/download/download-archives---repository-manager-oss

Post-Installation steps

• Remove SNAPSHOT version from previous releases from the nexus repository #660 Remove unused SNAPSHOTS
• optimize Nexus disk space usage
• limit content of repo to deegree RELEASES and SNAPSHOTS (public) and Third party libs required to build deegree (protected repository)

References:

• https://support.sonatype.com/hc/en-us/articles/213464138-How-do-I-upgrade-Nexus-Repository-Manager-2-x-to-2-y
• https://help.sonatype.com/repomanager3/upgrading#Upgrading-Upgradingfrom2.xto2.y
• https://support.sonatype.com/hc/en-us/articles/213464338-Nexus-Repository-Manager-Upgrade-and-Compatibility-Notes
• https://help.sonatype.com/repomanager3/installation/run-as-a-service
• https://help.sonatype.com/repomanager3/installation/run-behind-a-reverse-proxy
• https://support.sonatype.com/hc/en-us/articles/213464278-How-to-Reset-Nexus-Logging-Configuration
• https://support.sonatype.com/hc/en-us/articles/213465138-How-can-I-optimize-Nexus-2-to-minimize-disk-space-used-

[stephanr]

In order to inform our users, we should also announce the maintenance on our website.
This could also be possible done through a tweet.

[tfr42]

During downtime the latest release versions can be downloaded via the Github site.

Manually uploaded the release WAR/ZIP files for 3.4.8 and 3.3.21 to
https://github.com/deegree/deegree3/releases

[tfr42]

Moving to OSGeo repo is may be an alternative, see #1075

[tfr42]

Nexus has been updated to v3.0 and is available at http://nexus3.deegree.org or it's alias https://repo.deegree.org. Was part of #1130.