feat: refactor to single instance garm client with auto init and login

[rafalgalaw]

Creates the garm-api client once as a single instance, so there are no more unnecesary login api calls on every reconcile. Also the operator initializes garm-server automatically again and attempts a login, once the garm-server dies or the auth token expires.

Essentially in main the client gets created once

main.go

if err = client.CreateInstance(client.GarmScopeParams{
	BaseURL:  config.Config.Garm.Server,
	Username: config.Config.Garm.Username,
	Password: config.Config.Garm.Password,
	Email:    config.Config.Garm.Email,
}); err != nil {
	return fmt.Errorf("unable to setup garm: %w", err)
}

Every garm-client method gets passed as callback to EnsureAuth

enterprise.go

func (s *enterpriseClient) ListEnterprises(param *enterprises.ListEnterprisesParams) (*enterprises.ListEnterprisesOK, error) {
	return EnsureAuth(func() (*enterprises.ListEnterprisesOK, error) {
		metrics.TotalGarmCalls.WithLabelValues("enterprises.List").Inc()
		enterprises, err := s.Client().Enterprises.ListEnterprises(param, s.Token())
		if err != nil {
			metrics.GarmCallErrors.WithLabelValues("enterprises.List").Inc()
			return nil, err
		}
		return enterprises, nil
	})
}

Inside EnsureAuth, the client method gets executed, and checked for a 401 http error, which would result in an intit and login call, before retrying the same client method again. The single instance client is then authenticated again for every caller.

client.go

func EnsureAuth[T interface{}](f Func[T]) (T, error) {
	result, err := f()
	if err != nil && IsUnauthenticatedError(err) {
		metrics.GarmCallErrors.WithLabelValues("client.Unauthenticated").Inc()

		err = Instance.Init()
		if err != nil {
			return result, err
		}

		err = Instance.Login()
		if err != nil {
			return result, err
		}

		result, err = f()
	}
	return result, err
}

[bavarianbidi]

nice refactoring, really like it ❤️
just one nit about variable naming

[bavarianbidi]

I'm bothered by the term Instance here ... Instance in the scope of GARM could be a Runner as well.

What do you think about one of the following two options:

• Instance will be renamed to GarmClient
• As BaseClient is an extended version of garmClient.GarmAPI, BaseClient will become GarmClient and with that Instance will be BaseClient (or just Client)

[rafalgalaw]

Yes you are right, this might be confusing. I´ll probably like the second option better: then its clear that a GarmClient is the defact Base which has all necessary methods for Auth and default API methods for all garm resources. And the Instance of it is an instanciated Client.

[bavarianbidi]

LGTM

just one idea came into my mind (could be a dedicated follow up PR)
expose the expiration-time of the current used token as metric.