feat(agent): extends /node_info response with storage_size.

This extends agent `/node_info` response with `stroage_size` and
`data_directory` fields.

pkg/cmd/agent/nodeinfo_linux.go

@@ -7,6 +7,7 @@ package main
 import (
 	"runtime"
 
+	"github.com/pkg/errors"
 	"github.com/scylladb/scylla-manager/v3/pkg/scyllaclient"
 	"golang.org/x/sys/unix"
 )
@@ -17,9 +18,16 @@ func (h *nodeInfoHandler) sysInfo(info *scyllaclient.NodeInfo) error {
 		return err
 	}
 
+	var statfs unix.Statfs_t
+	if err := unix.Statfs(info.DataDirectory, &statfs); err != nil {
+		return errors.Wrap(err, "statfs")
+	}
+	total := statfs.Blocks * uint64(statfs.Bsize)
+
 	info.MemoryTotal = int64(si.Totalram)
 	info.CPUCount = int64(runtime.NumCPU())
 	info.Uptime = si.Uptime
+	info.StorageSize = total
 
 	return nil
 }

pkg/cmd/agent/nodeinfo_others.go

@@ -15,5 +15,6 @@ func (h *nodeInfoHandler) sysInfo(info *scyllaclient.NodeInfo) error {
 	info.MemoryTotal = 0
 	info.CPUCount = 0
 	info.Uptime = 0
+	info.StorageSize = 0
 	return nil
 }

pkg/scyllaclient/config_client.go

@@ -286,6 +286,7 @@ func (c *ConfigClient) NodeInfo(ctx context.Context) (*NodeInfo, error) {
 		{Field: &ni.AlternatorAddress, Fetcher: c.AlternatorAddress},
 		{Field: &ni.AlternatorPort, Fetcher: c.AlternatorPort},
 		{Field: &ni.AlternatorHTTPSPort, Fetcher: c.AlternatorHTTPSPort},
+		{Field: &ni.DataDirectory, Fetcher: c.DataDirectory},
 	}
 
 	for i, ff := range ffs {