Guide to using the config-server

The server is centrally hosted on argus and is accessible anywhere within the Diamond network. You can quickly get a feel for it using FastAPI’s generated Swagger UI at https://daq-config.diamond.ac.uk/docs

This library provides a python client to easily make requests from Bluesky code. The client can use caching to prevent needlessly making time-consuming requests on data which won’t have changed. You can choose the maximum number of items it can hold as well as the lifetime of an item upon instantiation.

from daq_config_server.client import ConfigServer

config_server = ConfigServer("https://daq-config.diamond.ac.uk", cache_size = 10, cache_lifetime_s = 3600)

You can then make a request through this client through its get_file_contents function. If you are reading a file which may have changed since the client last read it, you should set the appropriate flag to reset the cache for that result - this forces a new request and stores that new result in the cache.

config_server.get_file_contents(FILE_PATH,reset_cached_result=True)

By default, this will return the file’s raw string output - which includes things like linebreaks. It is up to you to format this output - using splitlines() will get you a list where each item is a line in the file. get_file_contents has a desired_return_type parameter where you can instead ask for a dict or bytes. The server will try and do the conversion, and respond with an HTTP error if the requested file is incompatible with that type.

Adding files to the whitelist

For security reasons, only files existing on the whitelist can be read. Please make a PR to add a file to the whitelist. If unsure, please ask in the #daq-config-server slack channel or create a GitHub issue. To make the config-server as quick to use as possible, the server will check any requests against the whitelist.yaml file on the main branch of the repository, rather than the whitelist in the latest release. The server will check for updates every 5 minutes.

Reading sensitive information

If you need to read a file which contains sensitive information, or dls-dasc doesn’t have the permissions to read your file, you should encrypt this file as a sealed secret on your beamline cluster, and mount this in your BlueAPI service.