cluster: load regions when scanning a directory

Signed-off-by: Alejandro Mery <amery@jpi.io>

pkg/cluster/cluster_scan.go

@@ -2,17 +2,25 @@ package cluster
 
 import (
 	"io/fs"
+	"path"
 	"sort"
 
 	"darvaza.org/core"
 )
 
+const (
+	// ZoneRegionsFileName indicates the file containing
+	// region names as references
+	ZoneRegionsFileName = "regions"
+)
+
 func (m *Cluster) scan(opts *ScanOptions) error {
 	for _, fn := range []func(*ScanOptions) error{
 		m.scanDirectory,
 		m.scanMachines,
 		m.scanZoneIDs,
 		m.scanSort,
+		m.initRegions,
 		m.scanGateways,
 		m.scanCephMonitors,
 	} {
@@ -24,7 +32,7 @@ func (m *Cluster) scan(opts *ScanOptions) error {
 	return nil
 }
 
-func (m *Cluster) scanDirectory(_ *ScanOptions) error {
+func (m *Cluster) scanDirectory(opts *ScanOptions) error {
 	// each directory is a zone
 	entries, err := fs.ReadDir(m.dir, ".")
 	if err != nil {
@@ -33,16 +41,14 @@ func (m *Cluster) scanDirectory(_ *ScanOptions) error {
 
 	for _, e := range entries {
 		if e.IsDir() {
-			z, err := m.newZone(e.Name())
+			ok, err := m.scanSubdirectory(opts, e.Name())
 			switch {
 			case err != nil:
 				return core.Wrap(err, e.Name())
-			case z.Machines.Len() == 0:
-				z.warn(nil).
-					WithField("zone", z.Name).
+			case !ok:
+				m.warn(nil).
+					WithField("zone", e.Name()).
 					Print("empty")
-			default:
-				m.Zones = append(m.Zones, z)
 			}
 		}
 	}
@@ -50,6 +56,27 @@ func (m *Cluster) scanDirectory(_ *ScanOptions) error {
 	return nil
 }
 
+func (m *Cluster) scanSubdirectory(_ *ScanOptions, name string) (bool, error) {
+	z, err := m.newZone(name)
+	switch {
+	case err != nil:
+		// somewhere went wrong scanning the subdirectory
+		return false, err
+	case z.Machines.Len() > 0:
+		// zones have machines and the regions they belong
+		m.Zones = append(m.Zones, z)
+		return true, nil
+	case len(z.Regions) > 0:
+		// regions have no machines but can include
+		// other regions
+		m.appendRegionRegions(name, z.Regions...)
+		return true, nil
+	default:
+		// empty
+		return false, nil
+	}
+}
+
 func (m *Cluster) newZone(name string) (*Zone, error) {
 	z := &Zone{
 		zones:  m,
@@ -154,31 +181,65 @@ func (z *Zone) scan() error {
 	}
 
 	for _, e := range entries {
-		if e.IsDir() {
-			m := &Machine{
-				zone:   z,
-				logger: z,
-				Name:   e.Name(),
-			}
+		name := e.Name()
 
-			m.debug().
-				WithField("node", m.Name).
+		switch {
+		case name == ZoneRegionsFileName:
+			err = z.loadRegions()
+		case e.IsDir():
+			err = z.scanSubdirectory(name)
+		default:
+			z.warn(nil).
 				WithField("zone", z.Name).
-				Print("found")
+				WithField("filename", name).
+				Print("unknown")
+		}
 
-			if err := m.init(); err != nil {
-				m.error(err).
-					WithField("node", m.Name).
-					WithField("zone", z.Name).
-					Print()
+		if err != nil {
+			return err
+		}
+	}
 
-				return err
-			}
+	return nil
+}
 
-			z.Machines = append(z.Machines, m)
+func (z *Zone) loadRegions() error {
+	filename := path.Join(z.Name, ZoneRegionsFileName)
+	regions, err := z.zones.ReadLines(filename)
+
+	if err == nil {
+		// parsed
+		err = z.appendRegions(regions...)
+		if err != nil {
+			err = core.Wrap(err, filename)
 		}
 	}
 
+	return err
+}
+
+func (z *Zone) scanSubdirectory(name string) error {
+	m := &Machine{
+		zone:   z,
+		logger: z,
+		Name:   name,
+	}
+
+	m.debug().
+		WithField("node", m.Name).
+		WithField("zone", z.Name).
+		Print("found")
+
+	if err := m.init(); err != nil {
+		m.error(err).
+			WithField("node", m.Name).
+			WithField("zone", z.Name).
+			Print()
+
+		return err
+	}
+
+	z.Machines = append(z.Machines, m)
 	return nil
 }
 

pkg/cluster/regions.go

@@ -106,6 +106,38 @@ func (m *Cluster) setRegionZones(name string, zones ...*Zone) {
 	})
 }
 
+func (m *Cluster) appendRegionRegions(name string, subs ...string) {
+	for i := range m.Regions {
+		r := &m.Regions[i]
+
+		if name == r.Name {
+			// found
+			r.Regions = append(r.Regions, subs...)
+			return
+		}
+	}
+
+	// new
+	m.Regions = append(m.Regions, Region{
+		Name:    name,
+		Regions: subs,
+	})
+}
+
+func (z *Zone) appendRegions(regions ...string) error {
+	for _, s := range regions {
+		// TODO: validate
+		z.debug().
+			WithField("zone", z.Name).
+			WithField("region", s).
+			Print("attached")
+
+		z.Regions = append(z.Regions, s)
+	}
+
+	return nil
+}
+
 func (m *Cluster) finishRegion(r *Region) {
 	if r.m != nil {
 		// ready