[CU-86b2qymcx] Enable k8s-injected credentials

[jfuerth]

This initial implementation requires low-level configuration of the client:

dnastack config contexts add data-connect-k8s
dnastack config contexts use data-connect-k8s
dnastack config endpoints add --type data_connect data-connect
dnastack config endpoints set data-connect url https://collection-service.staging.dnastack.com/data-connect/
dnastack config endpoints set data-connect authentication.client_id loader-cronjob-client
dnastack config endpoints set data-connect authentication.resource_url https://publisher-data.staging.dnastack.com/
dnastack config endpoints set data-connect authentication.token_endpoint https://wallet.staging.dnastack.com/oauth/token
dnastack config endpoints set data-connect authentication.grant_type client_credentials
dnastack config endpoints set data-connect authentication.client_assertion_file /var/run/secrets/kubernetes.io/serviceaccount/token

The plan for the future is to have dnastack use ${service-registry-url} detect if:

• the file /var/run/secrets/kubernetes.io/serviceaccount/token exists
• the terminal is non-interactive

and if so, edit all the service registry endpoint authentication objects on the fly, making the following edits:

• add client_assertion_file with the path to the k8s token
• replace client_id with the one found in the client_assertion_file
• replace grant_type with client_credentials
• null out client_secret

If this happens, the CLI will print a message that says so, and it'll offer some switch like --no-k8s-auth to inhibit this behaviour.

[platform-automation-dnastack]

Task linked: CU-86b2qymcx Support platform-injected credentials in dnastack CLI