hosts: add generators for hosts files

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

pkg/cluster/hosts.go

@@ -0,0 +1,128 @@
+package cluster
+
+import (
+	"bytes"
+	"fmt"
+	"strings"
+	"text/template"
+)
+
+type hostsFile struct {
+	Ring0 []hostsEntry
+	Ring1 []hostsEntry
+}
+
+type hostsEntry struct {
+	Addr  string
+	Names []string
+}
+
+var hostsTemplate = template.Must(template.New("hosts").Funcs(template.FuncMap{
+	"StringsJoin": strings.Join,
+}).Parse(`127.0.0.1 localhost
+
+# The following lines are desirable for IPv6 capable hosts
+::1     ip6-localhost ip6-loopback
+fe00::0 ip6-localnet
+ff00::0 ip6-mcastprefix
+ff02::1 ip6-allnodes
+ff02::2 ip6-allrouters
+ff02::3 ip6-allhosts
+
+{{range .Ring1 -}}
+{{.Addr}}  {{StringsJoin .Names " "}}
+{{end}}
+{{range .Ring0 -}}
+{{.Addr}}  {{StringsJoin .Names " "}}
+{{end -}}
+`))
+
+// WriteHosts rewrites all hosts files on the tree
+func (m *Cluster) WriteHosts() error {
+	var err error
+
+	m.ForEachZone(func(z *Zone) bool {
+		err = z.WriteHosts()
+		return err != nil
+	})
+
+	return err
+}
+
+// WriteHosts rewrites all hosts files in the zone
+func (z *Zone) WriteHosts() error {
+	var err error
+
+	s := z.Hosts()
+	z.ForEachMachine(func(p *Machine) bool {
+		err = p.WriteStringFile(s, "hosts")
+		return err != nil
+	})
+
+	return err
+}
+
+// WriteHosts rewrites the hosts file
+func (p *Machine) WriteHosts() error {
+	s := p.zone.Hosts()
+	return p.WriteStringFile(s, "hosts")
+}
+
+func (z *Zone) genHosts(out *hostsFile, p *Machine) {
+	var names []string
+
+	ip, _ := RingOneAddress(p.zone.ID, p.ID)
+	names = append(names, p.Name)
+
+	if p.CephMonitor {
+		names = append(names, fmt.Sprintf("%s-%s", p.zone.Name, "ceph"))
+		names = append(names, fmt.Sprintf("%s-%s", p.zone.Name, "k3s"))
+
+		if z.ID == p.zone.ID {
+			names = append(names, "ceph")
+			names = append(names, "k3s")
+		}
+	}
+
+	entry := hostsEntry{
+		Addr:  ip.String(),
+		Names: names,
+	}
+
+	out.Ring1 = append(out.Ring1, entry)
+
+	if p.IsGateway() {
+		var s string
+
+		ip, _ = RingZeroAddress(p.zone.ID, p.ID)
+		s = fmt.Sprintf("%s-%v", p.Name, 0)
+
+		entry = hostsEntry{
+			Addr:  ip.String(),
+			Names: []string{s},
+		}
+
+		out.Ring0 = append(out.Ring0, entry)
+	}
+}
+
+// Hosts renders the /etc/hosts to be used on this zone
+func (z *Zone) Hosts() string {
+	var buf bytes.Buffer
+	var out hostsFile
+
+	z.zones.ForEachZone(func(z2 *Zone) bool {
+		z2.ForEachMachine(func(p *Machine) bool {
+			z.genHosts(&out, p)
+
+			return false
+		})
+		return false
+	})
+
+	if err := hostsTemplate.Execute(&buf, &out); err != nil {
+		panic(err)
+	}
+
+	return buf.String()
+}