Allow service to start without config file

[tpo]

If the service gets started without a config file:

docker run -ti sourcepole/qwc-ldap-auth

then it will report an error:

[2025-04-16 09:05:33,979] ERROR in runtime_config: Could not load runtime config '/srv/qwc_service/config/default/ldapAuthConfig.json':
[Errno 2] No such file or directory: '/srv/qwc_service/config/default/ldapAuthConfig.json'

Is that a problem?

If not, then I propose to transform the ERROR into an INFO log message. Do you concur?

Note to self: this fixes the error:

$ cat ./ldapAuthConfig.json 
{
  "$schema": "https://github.com/qwc-services/qwc-ldap-auth/raw/master/schemas/qwc-ldap-auth.json",
  "service": "ldap-auth",
  "config": {
  }
}
$ docker run -ti  --mount type=bind,src=./ldapAuthConfig.json,dst=/srv/qwc_service/config/default/ldapAuthConfig.json sourcepole/qwc-ldap-auth

[tpo]

Here I'd suggest:

config_handler = RuntimeConfig("ldapAuth", app.logger)

to add an option:

config_handler = RuntimeConfig("ldapAuth", app.logger, config_file_is_optional=true)

An implementation of this proposal on the qwc-services-core's side can be found in qwc-services/qwc-services-core#20

[manisandro]

One thought is that there is a bit of a risk of introducing heterogeneity throughout the QWC services: currently all expect a config file to exist and (at least if schema validation is enabled in the config generator) expect the config to conform to the respective schema. I guess the use-case here is to control the settings through Envs and not though the json config, but is it really required to use Envs here rather than just using the config?

[tpo]

One thought is that there is a bit of a risk of introducing heterogeneity throughout the QWC services: currently all expect a config file to exist and (at least if schema validation is enabled in the config generator) expect the config to conform to the respective schema. I guess the use-case here is to control the settings through Envs and not though the json config, but is it really required to use Envs here rather than just using the config?

I agree. As far as I understand there is no reason to configure the service via environment variables. It could just as well be configured via the config file.

I guess the service gets configured by ENV variables now for historical reasons - it got done that way a long time ago before qwc-services had a coherent structure.

So it could just as well get configured via the config file. If that is the way forward then everybody upgrading their existing qwc-ldap-service will need to move their current ENV based configuration into a config file.

What do you think @pka ?