Breaking change with v1.4: experiment k8s service created even if steps are not weighted

[fwippe]

Checklist:

• I've included steps to reproduce the bug.
• I've included the version of argo rollouts.

Describe the bug
Even for simple experiments, i.e., without any weighted steps, Argo always creates corresponding k8s services.
This behavior was introduced with this PR. According to the docs a service should only be created if there are weighted experiment steps.

Can you maybe elaborate on the reasons for this breaking change? Why do you always create a k8s service even if it's not needed?

Why is this a breaking change?

After upgrading to version 1.4, suddenly experiments were failing with different error messages complaining about missing or invalid k8s service properties (like service name too long (> 63 chars) or missing port name attribute).

Expected behavior

• Argo rollouts should not create an additional experiment service if there are no weighted experiment steps

Version
v1.4.0

Message from the maintainers:

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[zachaller]

@fwippe Yea that was a big miss on my part sorry for the change in behavior, I have been talking with alex and dani who originally had the request for a use case they had which does make sense. We tried to do the change in a non spec changing way which resulted in this change in behavior.

The plan is going forward will be to revert the change in behavior in a 1.4.1 release that I will be doing here soon to keep the expected behavior and look into possible other solutions to support always creating services for inline experiments all the time.

I will be noting in the release notes for 1.4.1 that there was an unintended change in behavior that was reverted for 1.4.1 as well.