Names of environment variables used for multihost testing

[psss]

Each guest provided in the provision step config of a multihost plan can specify a role. The plan is to provide the list of all guests assigned a given role to each test using an environment variable.

We need to decide how the role name should be mapped to the environment variable name as it may contain both lowercase and uppercase characters while, as for now, we keep all environment variables consistent using uppercase only.

Let's decide this as soon as possible to prevent any backward-incompatible changes later. For the following config:

provision:
    how: virtual
    name: replica-one
    role: rEpLiCa

There are three options:

1. keep unchanged
2. lowercase all chars
3. uppercase all chars

[kkaarreell]

Btw, I have verified that in Restraint the exact role is followed, i.e. <task name="(keylime-tests) /Multihost/sync" role="CLIEnts"> results in a variable CLIEnts containing the respective hostname.

[lukaszachy]

Is 'role' case sensitive within tmt usage? e.g. If i have plan with role: replica and role: REPLICA will tmt treat as two distinct roles?

[happz]

The later, as the very basic comparison is used:

The role/where matching is case sensitive:

    def enabled_on_guest(self, guest: 'Guest') -> bool:
        """ Check if the plugin is enabled on the specific guest """

        # FIXME: cast() - typeless "dispatcher" method
        where = cast(List[str], self.get('where'))

        if not where:
            return True

        return any(destination in (guest.name, guest.role) for destination in where)

[sopos]

It should be, I guess. If not, it should be fixed.

[lukaszachy]

So we have no choice but to keep role as-is for the variable name - otherwise more roles will report under same variable.

[psss]

I believe we still have a choice: Clearly state that it is not a good idea to have two separate roles with the same name, distinguished only by the case of the letter. We can do this by implementation: Provided role name could be always converted to lowercase.

[sopos]

Not being a good idea does not mean we should take this freedom out of the users.

[psss]

Summary from today's hacking session:

• Keep the role name intact, do not do any normalization
• Use the name exactly as provided by the user for the environment variable name
• In the very same way use it for the TMT_GUEST_ROLE value
• Warn user if the provision step contains two roles differing only in letter case

Thanks for your votes and feedback!