ceph: zones.Zones.WriteCephConfig() and ceph.Config.WriteTo()

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

pkg/ceph/config.go

@@ -1,8 +1,11 @@
 package ceph
 
 import (
+	"bytes"
+	"fmt"
 	"io"
 	"net/netip"
+	"strings"
 
 	"github.com/gofrs/uuid/v5"
 
@@ -22,6 +25,32 @@ type GlobalConfig struct {
 	ClusterNetwork netip.Prefix `ini:"cluster_network"`
 }
 
+// WriteTo writes a Wireguard [Config] onto the provided [io.Writer]
+func (cfg *Config) WriteTo(w io.Writer) (int64, error) {
+	var buf bytes.Buffer
+
+	writeGlobalToBuffer(&buf, &cfg.Global)
+	return buf.WriteTo(w)
+}
+
+func writeGlobalToBuffer(w *bytes.Buffer, c *GlobalConfig) {
+	_, _ = w.WriteString("[global]\n")
+	_, _ = fmt.Fprintf(w, "%s = %s\n", "fsid", c.FSID.String())
+	_, _ = fmt.Fprintf(w, "%s = %s\n", "mon_initial_members", strings.Join(c.Monitors, ", "))
+	_, _ = fmt.Fprintf(w, "%s = %s\n", "mon_host", joinAddrs(c.MonitorsAddr, ", "))
+	_, _ = fmt.Fprintf(w, "%s = %s\n", "cluster_network", c.ClusterNetwork.String())
+}
+
+func joinAddrs(addrs []netip.Addr, sep string) string {
+	s := make([]string, len(addrs))
+
+	for i, addr := range addrs {
+		s[i] = addr.String()
+	}
+
+	return strings.Join(s, sep)
+}
+
 // NewConfigFromReader parses the ceph.conf file
 func NewConfigFromReader(r io.Reader) (*Config, error) {
 	doc, err := basic.Decode(r)

pkg/zones/ceph.go

@@ -31,6 +31,18 @@ func (m *Zones) GetCephConfig() (*ceph.Config, error) {
 	return ceph.NewConfigFromReader(r)
 }
 
+// WriteCephConfig writes the ceph.conf file
+func (m *Zones) WriteCephConfig(cfg *ceph.Config) error {
+	f, err := m.CreateTruncFile("ceph.conf")
+	if err != nil {
+		return err
+	}
+	defer f.Close()
+
+	_, err = cfg.WriteTo(f)
+	return err
+}
+
 // GenCephConfig prepares a ceph.Config using the cluster information
 func (m *Zones) GenCephConfig() (*ceph.Config, error) {
 	fsid, err := m.GetCephFSID()