Stackdriver multi-tenant configuration not supported

[lucabrunox]

Is your feature request related to a problem? Please describe.

With fluent-operator in K8s, in a multi-tenant configuration where I only have access to my own namespace, I don't have permissions to configure the fluentbit pods configuration to mount a secret. I also don't want to do that because otherwise other tenants would have access to that secret.

So I need a way in "Output" of stackdriver itself to put the google json credentials.

Describe the solution you'd like

I need a way to specify the json credentials using just "Output" because I can't change "FluentBit" config, also I don't want other tenants to use my secret.

Describe alternatives you've considered

I tried to use "service_account_email" and "service_account_secret" but unfortunately it sets only the ->private_key field and then fluentbit fails with "project_id" is not set:

[2025/09/23 16:42:03] [error] [output:stackdriver:stackdriver.0] error creating RSA context
[2025/09/23 16:42:03] [error] [output:stackdriver:stackdriver.0] JWT signature generation failed
[2025/09/23 16:42:03] [ warn] [output:stackdriver:stackdriver.0] token retrieval failed
[2025/09/23 16:42:03] [error] [output:stackdriver:stackdriver.0] property 'project_id' is not set
[2025/09/23 16:42:03] [error] [output] failed to initialize 'stackdriver' plugin
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