Hi @chancez , we are making some changes for inter-cluster communication in scope of 0.19 release now. This PR should go after we are done with those changes.

Also, I think it makes sense to move user/password for inter-cluster communication at cluster level. It is not a part of hostTemplate.

@alex-zaitsev sure, that seems reasonable. So next to the secret field I added then?

If we move it from the host configuration, how is this supposed to be configured for the auto-generated clusters? https://github.com/Altinity/clickhouse-operator/blob/master/pkg/model/ch_config_generator.go#L336-L398

@alex-zaitsev Thoughts on how to deal with configuring auto generated clusters when internode authentication is configured?

@sunsingerus , there are two distinct changes here:

1. Using <secret> for inter-cluster communication.
2. Using user/pass.

I think <secret> should be default if it passes all tests

@chancez , we will implement the following:

  configuration:
    clusters:
      - name: default
        secure: yes # (default off) turns on HTTPS
        secret:
          auto: yes          # (default) operator creates a secret with name {chi}-{cluster}-interserver-secret and random hash as secret
          value: abcd        # Use explicit secret value
          valueSecretKeyRef: # Use secret reference
            ... 

@alex-zaitsev Sounds good. I can rebase and I think this PR is pretty close to the configuration you've suggested, so hopefully this can be merged soon then.

@alex-zaitsev I'm looking back into this but my question from earlier is still unanswered:

Thoughts on how to deal with configuring auto generated clusters when internode authentication is configured?

Setting secure at the cluster level makes sense to me, but the auto-generated clusters don't have a cluster context. Should I just set <secure>1</secure> if the user defines any clusters with secure: true? If the user defines more than 1 cluster, one with secure, one without, then how should auto-generated clusters be configured? Secure or not? Should I just not worry about the auto generated clusters (even though they won't work?). This was one motivation I had for configuring the secure field on the hostTemplate level. Perhaps both should be supported? Same issue applies to the <secret> and <username>, etc as well.

@chancez , secrets for inter-cluster communication are implemented in 0.20.0. See usage examples:
https://github.com/Altinity/clickhouse-operator/blob/0.20.0/docs/chi-examples/21-secure-cluster-secret-01-auto.yaml
https://github.com/Altinity/clickhouse-operator/blob/0.20.0/docs/chi-examples/21-secure-cluster-secret-02-plaintext.yaml
https://github.com/Altinity/clickhouse-operator/blob/0.20.0/docs/chi-examples/21-secure-cluster-secret-03-secret-ref.yaml