Setup golden DB in merge-ci

[joshmoore]

cc: @pwalczysko

[sbesson]

Added some notes capturing how this feature had been implemented in ci.openmicroscopy.org a few years back with @pwalczysko.

Minimally, this implementation can be seen as an extension of the PURGE_DATA option in devspace 0.11.0 as:

devspace/home/jobs/OMERO-server/config.xml

Lines 55 to 60 in 6e1187d

	if [ "$PURGE_DATA" = "true" ]; then
	dropdb -h $OMERO_DB_HOST -U $OMERO_DB_USER $OMERO_DB_NAME || echo "First run or already exists"
	rm -rf $OMERO_DATA_DIR
	else
	echo "Skipping PURGE_DATA:CleanDbAndRepo"
	fi

In addition to these comamnds purging the database and the binary repository, a subsequent step is to restore an existing reference DB + binary repo. There are a few assumptions here:

• the database and the binary repo need to be available from the Jenkins environment

• the golden DB to be created in a systematic way (pg_dump format, disk layout)

• enough space need to be provisioned esp. for large valuable DBs. By default, the data directory is in the same place as the devspace clone.

  devspace/home/jobs/OMERO-server/config.xml

  Lines 19 to 23 in 0b06377

  	<hudson.model.StringParameterDefinition>
  	<name>DATA_DIR</name>
  	<description>Default is $HOME/omero-server-data</description>
  	<defaultValue>$HOME/omero-server-data</defaultValue>
  	</hudson.model.StringParameterDefinition>

  Minimally, this variable would need to be overriden or the path on disk symlinked to a larger volume with appropriate write permissions.