ILM setup misleads user when check_exists is false

[adriansr]

When a Beat is run with setup.ilm.check_exists: false

It prints:

INFO	[index-management]	idxmgmt/std.go:309	Write alias successfully generated.

However, that is not true, as the function creating the write alias is silently skipping the creation of the index due to check_exists being false:

  if err := m.ilm.EnsureAlias(); err != nil {
	  if ilm.ErrReason(err) != ilm.ErrAliasAlreadyExists {
		  return err
	  }
	  log.Info("Write alias exists already")
  } else {
	  log.Info("Write alias successfully generated.")
  }
[...]
func (m *stdManager) EnsureAlias() error {
	if !m.checkExists {
		return nil
	}

	b, err := m.client.HasAlias(m.alias.Name)
	if err != nil {
		return err
	}
	if b {
		return nil
	}

	// This always assume it's a date pattern by sourrounding it by <...>
	return m.client.CreateAlias(m.alias)
}

In the scenario were ILM is not setup properly, this will result in the write index not being created. An index named after the write index created instead.

[elasticmachine]

Pinging @elastic/integrations-services (Team:Services)

[elasticmachine]

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