Pass the full Tahoe-LAFS configuration IFoolscapStoragePlugin.get_client_resource

[exarkun]

IFoolscapStoragePlugin methods are defined as taking a dict containing only the part of tahoe.cfg that is specifically for them. That is, the server method gets the contents of the [storage.plugins.<plugin name>] section and the client methods get the [storageclient.plugins.<plugin name>] section.

This was done to try to keep the values access as limited as possible. All else being equal, fewer things is better than more things.

However, it seems clear now that this is too limited. For example, a plugin can't even find the node directory with this little information. If a plugin wants to keep some state with the node, it has no way to know where that should be.

The _Config object is much more useful and provides helpful abstractions that we would like to encourage to be used in Python code - for example, write_private_config instead of finding out the node directory, constructing a path to a file in the private directory, and then directly performing I/O on that file.

So, instead of passing only the plugin's config section, pass a _Config instance.

[exarkun]

To keep the changeset small, I'll do this a piece at a time. First, get_client_resource.

[exarkun]

​https://github.com/tahoe-lafs/tahoe-lafs/pull/650

[exarkun]

Merged into integration branch in ​https://github.com/tahoe-lafs/tahoe-lafs/commit/2c9e724996a278b20596d506b37fa45bc17ac996

[GitHub <noreply@…>]

In 2c9e724/trunk:

Merge pull request #650 from tahoe-lafs/3242.pass-config-object-to-storage-plugin-client-resource

Pass _Config object to storage plugin client resource

Fixes: ticket:3242