nmon/internal/backup/backup_vm.go

package backup

import (
	"context"
	"fmt"
	"os"
	"path/filepath"
	"time"

	"github.com/v10networks/nmon/internal/config"
	"github.com/v10networks/nmon/internal/vmsup"
)

// addMetricStores snapshots each store through its own API, archives the snapshot directory under
// "<name>/" and deletes the snapshot. A store without a local DataDir is skipped with a manifest note.
func addMetricStores(ctx context.Context, o *Options, aw *archiveWriter, m *Manifest) error {
	for _, vs := range o.Stores {
		if vs.DataDir == "" || vs.URL == "" {
			m.Notes = append(m.Notes, fmt.Sprintf("store %s is external and was not backed up", vs.Name))
			continue
		}
		sm, err := backupOneStore(ctx, o, aw, vs, m.Boundary)
		if err != nil {
			return fmt.Errorf("backup: %s store: %w", vs.Name, err)
		}
		m.Stores = append(m.Stores, sm)
		logf(o.Log, "backup: %s store snapshot archived (%d series fingerprinted)\n", vs.Name, len(sm.Series))
	}
	return nil
}

func backupOneStore(ctx context.Context, o *Options, aw *archiveWriter, vs VMStore, boundary time.Time) (sm StoreManifest, err error) {
	api := vmAPI{hc: o.HTTP, base: vs.URL}
	name, err := api.createSnapshot(ctx)
	if err != nil {
		return sm, err
	}
	defer func() {
		// The caller's context may be the reason we are failing; deleting the snapshot must still happen.
		dctx, cancel := context.WithTimeout(context.WithoutCancel(ctx), time.Minute)
		defer cancel()
		if derr := api.deleteSnapshot(dctx, name); derr != nil && err == nil {
			err = derr
		}
	}()
	dir := filepath.Join(vs.DataDir, "snapshots", name)
	if _, err := os.Stat(dir); err != nil {
		return sm, fmt.Errorf("snapshot directory: %w", err)
	}
	if err := aw.addTree(vs.Name, dir); err != nil {
		return sm, err
	}
	series, err := api.sampleChecks(ctx, boundary)
	if err != nil {
		return sm, fmt.Errorf("fingerprint series: %w", err)
	}
	return StoreManifest{Name: vs.Name, Series: series}, nil
}

// StoresFromStatus turns the supervisor's Status() into the stores to back up. An external store has no
// local data directory, so it is listed without one and skipped.
func StoresFromStatus(dataDir string, status []vmsup.ChildStatus) []VMStore {
	out := make([]VMStore, 0, len(status))
	for _, c := range status {
		vs := VMStore{Name: c.Store, URL: c.URL}
		if !c.External {
			vs.DataDir = config.HotDir(dataDir)
			if c.Store == vmsup.StoreLong {
				vs.DataDir = config.LongDir(dataDir)
			}
		}
		out = append(out, vs)
	}
	return out
}