Consider minimizing the UpdateConfiguraton API.

[rompetroll]

Layers are currently required to implement UpdateConfiguration(config *common.Config) common.LayerError, and in addition Dataset(dataset string) (common.Dataset, common.LayerError).

The reason for this is that the specific implementation details of a layer dataset cannot be known to the common framework.

Given that a typical implementation of UpdateConfiguration looks like this:

func (dl *SomeDatalayer) UpdateConfiguration(config *common.Config) common.LayerError {
	existingDatasets := map[string]bool{}
	// update existing datasets
	for k, v := range dl.datasets {
		for _, dsd := range config.DatasetDefinitions {
			if k == dsd.DatasetName {
				existingDatasets[k] = true
				v.datasetDefinition = dsd
			}
		}
	}
	// remove deleted datasets
	for k := range dl.datasets {
		if _, found := existingDatasets[k]; !found {
			delete(dl.datasets, k)
		}
	}

	// add new datasets
	for _, dsd := range config.DatasetDefinitions {
		if _, found := existingDatasets[dsd.DatasetName]; !found {
			dl.datasets[dsd.DatasetName] = &Dataset{
				logger:            dl.logger,
				db:                dl.db,
				datasetDefinition: dsd,
			}
		}
	}

	return nil
}

and a typical Dataset implementation looks like this

func (dl *SomeDatalayer) Dataset(dataset string) (common.Dataset, common.LayerError) {
	ds, found := dl.datasets[dataset]
	if found {
		return ds, nil
	}
	return nil, ErrDatasetNotFound(dataset)
}

... it seems that all the layer really should need to provide is how to map a DatasetDefinition to a custom Dataset instance. And then the common framework can provide UpdateConfiguration and a Dataset impl under the hood.
The framework can then also automatically call UpdateConfiguration as part of the bootstap invocation, currently users have to remember to call it once as part of their layer constructor.