Allow omero.server.nodedescriptors to be queried from a client

[chris-allan]

It is useful for clients to know that specific services are disabled. In particular PixelData-0 for warning users about a lack of pyramid generation or Tables-0 for warning users about OMERO.tables services being unavailable.

/cc @sbesson, @stick, @atTODO

[sbesson]

Tested against a server using the default configuration (property unset)

Python 3.6.8 (default, Aug  7 2019, 17:28:10) 
[GCC 4.8.5 20150623 (Red Hat 4.8.5-39)] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import omero
>>> c=omero.client("localhost")
>>> s=c.createSession("root","omero")
>>> s.getConfigService().getConfigValue("omero.server.nodedescriptors")
''
>>> c.closeSession()

and with the property set

Python 3.6.8 (default, Aug  7 2019, 17:28:10) 
[GCC 4.8.5 20150623 (Red Hat 4.8.5-39)] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import omero
>>> c=omero.client("localhost")
>>> s=c.createSession("root","omero")
>>> s.getConfigService().getConfigValue("omero.server.nodedescriptors")
'master:Blitz-0,Tables-0'
>>> c.closeSession()

Everything is working as expected. Exposing this property client-side makes sense to me.

[joshmoore]

seealso:

• https://omero.readthedocs.io/en/stable/sysadmins/config.html#omero.server.nodedescriptors
• https://omero.readthedocs.io/en/stable/sysadmins/grid.html#deployment-examples

This seems safe and in keeping with the property's purpose.

NB: Having not looked at these in a while this makes me realize a couple of things that I'll list here but are obviously for elsewhere:

• There likely should be a way to query all such accessible properties.
• They should likely be listed as such in the documentation.
• And possibly a way to do this is to read the security status from the .properties file rather than the Spring .xml.

[sbesson]

There likely should be a way to query all such accessible properties.

From a quick testing, passing the wildcard to IConfig.getConfigValues() seems to be sufficient to retrieve all client-visible properties:

>>> s.getConfigService().getConfigValues(".*").keys()
dict_keys(['omero.client.ui.tree.orphans.name', 'omero.client.browser.thumb_default_size', 'omero.client.viewer.initial_zoom_level', 'omero.client.download_as.max_size', 'omero.sessions.max_user_time_to_idle', 'omero.cluster.read_only.runtime.repo', 'omero.client.ui.menu.dropdown.colleagues.label', 'omero.client.web.host', 'omero.security.password_required', 'omero.pixeldata.max_projection_bytes', 'omero.bioformats.version', 'omero.client.ui.menu.dropdown.leaders.label', 'omero.pixeldata.max_tile_length', 'omero.sessions.timeout', 'omero.upgrades.url', 'omero.client.ui.menu.dropdown.everyone.enabled', 'omero.pixeldata.tile_height', 'omero.version', 'omero.mail.config', 'omero.pixeldata.max_plane_width', 'omero.db.authority', 'omero.client.viewer.interpolate_pixels', 'omero.cluster.read_only.runtime.db', 'omero.client.ui.tree.orphans.enabled', 'omero.pixeldata.max_plane_float_override', 'omero.client.ui.tree.orphans.description', 'omero.client.ui.menu.dropdown.leaders.enabled', 'omero.client.ui.menu.dropdown.everyone.label', 'omero.pixeldata.max_plane_height', 'omero.sessions.maximum', 'omero.client.ui.menu.dropdown.colleagues.enabled', 'omero.sessions.max_user_time_to_live', 'omero.router.insecure', 'omero.bioformats.date', 'omero.bioformats.vcs_revision', 'omero.client.viewer.roi_limit', 'omero.server.nodedescriptors', 'omero.pixeldata.tile_width', 'omero.client.scripts_to_ignore', 'omero.client.ui.tree.type_order', 'omero.db.uuid#1', 'omero.pixeldata.backoff'])

They should likely be listed as such in the documentation.
And possibly a way to do this is to read the security status from the .properties file rather than the Spring .xml.

I was hoping the API above could be used integrated in the generation script but the properties glossary is create by the output of omero config parse which does not require an active session so it's longer than a 5min work.
I think it makes sense to capture the documentation RFE as an issue against omero-documentation.

[joshmoore]

From a quick testing, passing the wildcard to IConfig.getConfigValues() seems to be sufficient to retrieve all client-visible properties:

👍

I think it makes sense to capture the documentation RFE as an issue against omero-documentation.

👍 see ome/omero-documentation#2280