Resolve "faq entry to set datastore configuration in resconfig"

Closes #438 (closed)

docs/faqs.md

@@ -26,4 +26,17 @@ cfg.default_worker.accounts.append(None)
 cfg.default_worker.default_account = None
 cfg.to_file(get_resconfig_loc())
 ```
-Then run `texts` again. Then use the [variable update](scl.md#dealing-with-failures) (using `:=`) to inforce re-evaluation of the resources. A simple `%rerun var` will not be sufficient.
\ No newline at end of file
+Then run `texts` again. Then use the [variable update](scl.md#dealing-with-failures) (using `:=`) to inforce re-evaluation of the resources. A simple `%rerun var` will not be sufficient.
+
+**Q**: How can I set a datastore configuration alternative to the default `$HOME/.fireworks/datastore_config.yaml`?
+
+**A**: This can be done using the [vre-middleware's](https://vre-middleware.readthedocs.io/en/latest/resconfig.html) Python API. For example, within an iPython command line session:
+```python
+from virtmat.middleware.resconfig import get_resconfig_loc, get_default_resconfig
+cfg = get_default_resconfig()
+wcfg = cfg.workers[0]
+wcfg.envvars.update({'DATASTORE_CONFIG': '/alternative/path_to/my_project/datastore_config.yaml'})
+wcfg.default_envvars.append('DATASTORE_CONFIG')
+cfg.default_worker = wcfg
+cfg.to_file(get_resconfig_loc())
+```